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REVIEW ARTICLE

The prevalence of camel brucellosis and associated risk factors: a global meta-epidemiological study

Maryam Dadar1, Sharaf S. Omar2, Youcef Shahali1, Yadolah Fakhri3*, Jacques Godfroid4*, Amin Mousavi Khaneghah5, 6

1Razi Vaccine and Serum Research Institute (RVSRI), Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran;

2Department of Nutrition and Food Processing, Faculty of Agricultural Technology, AL-Balqa Applied University, Jordan;

3Food Health Research Center, Hormozgan University of Medical Sciences, Bandar Abbas, Iran;

4Department of Arctic and Marine Biology, Faculty of Biosciences, Fisheries and Economics, UiT – The Arctic University of Norway, Tromsø, Norway;

5 Department of Fruit and Vegetable Product Technology, Prof. Wacław Dąbrowski Institute of Agricultural and Food Biotechnology, Warsaw, Poland;

6Department of Food Science and Nutrition, Faculty of Food Engineering, State University of Campinas (UNICAMP), Sao Paulo, Brazil

Abstract

Camel brucellosis is a widespread and critical zoonotic infection caused by Brucella abortus and Brucella melitensis that negatively impact dairy and meat products. The current meta-analysis covers studies published over a course of 40 years, between 1 January 1980 and 1 April 2021, aiming to investigate the global prevalence of Brucella spp. in camels and related risk factors in different camel-keeping areas. Chi-squared test (I2 index) was applied to evaluate the heterogeneity of studies. A random-effect model (REM) estimated the pooled prevalence among subgroups. The literature search on camel brucellosis was performed among the available databases, including CABI, PubMed, Embase, Web of Science, Cochrane, Scielo, Scopus, and Science Direct. A total of 56 publications, comprising 205 data reports, were evaluated. Our results showed that the overall prevalence of camel brucellosis in the world was 9.23%. The lowest and highest prevalence rates of Brucella spp. infections among camels were reported in Oman (0.34%, 95%CI: 0.18–0.55) and Sudan (37.41%, 95%CI: 25.27–50.31), respectively. According to different risk factors, subgroup analysis showed that the location, sex, herd size, age, and mixed rearing with other animals could be considered the main risk factors impacting the occurrence of brucellosis in camels. The reported Brucella spp. in dromedary camel was Brucella melitensis (Biovar 1, 2, and 3), Brucella abortus (Biovar 3, 5, and 6), and Brucella suis. Our study represented remarkable differences between the prevalence of Brucella spp. in male (6.83% in 41 studies) and female (9.64% among 62 studies) camels. However, the present meta-epidemiological study would help improve control and surveillance approaches to prevent the spread of camel brucellosis among herds.

Key words: meta-epidemiology, brucellosis, camel, Brucella abortus, Brucella melitensis

*Corresponding Authors: Yadolah Fakhri, Food Health Research Center, Hormozgan University of Medical Sciences, Bandar Abbas, Iran. Email: ya.fakhri@gmail.com, ya.fakhri@hums.ac.ir; Jacques Godfroid, Department of Arctic and Marine Biology, Faculty of Biosciences, Fisheries and Economics, UiT – The Arctic University of Norway, Tromsø, Norway. Email: jacques.godfroid@uit.no

Received: 13 March 2022; Accepted: 5 May 2022; Published: 10 June 2022

DOI: 10.15586/qas.v14i3.1088

© 2022 Codon Publications
This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0). License (http://creativecommons.org/licenses/by-nc-sa/4.0/)

Introduction

The Camelidae family comprises two genera comprising the genus Camelus and the genus of lama (also named Camelids). The old-world genus of Camelus is divided into two species of Camelus dromedarius (the one-humped camel) and the Camelus bactrianus (the two-humped camel). Dromedary camels occupy the West Central and Near East Asia, North Africa, and Ethiopia (Wardeh, 2004). The habitat of the Camelus bactrianus is the cold deserts of China, East-Central Asia, and Mongolia (Jasra and Mirza, 2004). It is estimated that the world population of camels is 25.89 million, composed of 11% two-humped and 89% of one-humped dromedary camels (Kula and Tegegne, 2016). More than 60% of the dromedary camel population is habited in the countries of North-East Africa, such as Sudan, Kenya, Ethiopia, and Somalia (Gizachew et al., 2014). As a vital source of subsistence and income, the camel has socioeconomic effects on the survival of the populations of the arid and semi-dry areas living in Asia and Africa (Ahmad et al., 2010; Aujla et al., 1998). As camels are still an important part of the nomadic and pastoral livelihoods and because of the lack of mandatory vaccination programs for camels, the precise size of their population worldwide is difficult to determine. Like other livestock species, Camels are susceptible to brucellosis (Abbas and Agab, 2002; Gwida et al., 2012).

Exposure to pathogenic bacteria and fungi can endanger human and animal health (Chinakwe et al., 2019; Lu et al., 2021; Sabrina Mahyuddin et al., 2020). Brucellosis is a zoonotic bacterial infection caused by gram-negative bacteria from the Brucella genus, classified as a risk group III pathogen by the WHO. The control of this widespread disease is of high economic importance in different camel-rearing countries (Abbas and Agab, 2002; Chinakwe et al., 2019; Gwida et al., 2012; Lu et al., 2021; Mahyuddin et al., 2020). Brucellosis in a camel through the B. abortus and B. melitensis has been documented in all camel-keeping countries except Australia (Alamian and Dadar, 2019; Wernery, 2014). Camel brucellosis can induce significant productivity loss by long calving interval time, low herd fertility, comparatively low milk production, and late first calving age. Other studies also reported that brucellosis is responsible for abortion, stillbirth, and decreased appetite in the camel population (Abdel Hafez et al., 2015; Warsame et al., 2020).

The disease also can play an important role in the import and export of animals constraining livestock trade. It has been estimated that the seroprevalence of brucellosis is low (2–5%) in camels reared under extensively or nomadic husbandry systems and relatively high (8–15%) in semi-intensively or intensively rearing husbandry systems (Abbas and Agab, 2002). However, despite the developments of surveillance and control programs for camel herds, the prevalence of brucellosis showed an increasing trend in different developing countries because of numerous socioeconomic, sanitary, and political risk factors (Corbel, 2006; Pappas, 2010). Therefore, the zoonotic threat of camel brucellosis should be considered a severe public health problem, particularly in camel- rearing areas (Sprague et al., 2012). Infected camels and their derived products could be a source of human brucellosis, leading to severe arthritis, fever, infertility, and in some cases, chronic infections following misdiagnosis (Corbel, 2006; Gutema Wegi, 2020).

For this reason, serological surveillance of camel brucellosis; isolation of infected camel; proper disposal of placental tissues, aborted fetus, and uterine discharge; and disinfecting of contaminated areas are of overwhelming importance for the successful prevention and control of camel brucellosis (Abbas and Agab, 2002; Sprague et al., 2012). However, no meta-analysis is available on the prevalence of camel brucellosis worldwide. The present meta- epidemiological study is aimed to evaluate the global prevalence of camel brucellosis and the associated risk factors impacting the transmission of Brucella infection.

Material and methods

Search strategy

The meta-analysis of published data on camel brucellosis was performed following the Cochrane protocol (Higgins and Green, 2011). The data were extracted and selected according to the PRISMA (Preferred Reported Items for Systematic Reviews and Meta-Analyses) method (Figure 1) (Liberati et al., 2009). Available databases were screened for all publications on camel brucellosis, including CABI, PubMed, Embase, Cochrane, Scielo, Scopus, Web of Science, and Science Direct to retrieve related papers on brucellosis in the camel population from 1 January 1980 to 1 April 2021. The Medical Subject Headings (MeSH) terms used in this study were “Malta Fever,” “Brucella infection,” “prevalence,” OR “camel,” OR “Brucella spp.” ORB. melitensis” OR “B. abortus” OR “B. ovis” OR “brucellosis” OR “seroprevalence” OR “Camelus bactrianus” OR “Camelus dromedaries.” The selected articles were checked and cleaned in Endnote X7.8 for duplicates.

Figure 1. Flow chart of search processing based on Prisma.

Inclusion and exclusion criteria

The inclusion criteria in this study were considered as follows: (1) full-text article in English; (2) related subjects to camel brucellosis like infertility, for example, (3) original and descriptive investigations by qualitative or quantitative data, as case-control, cohort, cross-sectional, case reports, and case series studies; (4) research study on camel brucelloses like positive results and total sample sizes. In addition, clinical trials, thesis, books, workshops, and hosts other than camel and review article were excluded (Dadar et al., 2020; De Souza et al., 2021; Mokhtarian et al., 2020).

Data extraction

The data associated with camel brucellosis were extrac ted from all related articles that comprised the first author, geographic location, study period, type of sample, positive samples, diagnostic tests, isolated Brucella species, biovars, gender, and symptoms (if any). Articles were sorted according to detection method classification (direct (D) and indirect (ID)). Indirect methods such as serological tests could detect anti-Brucella antibodies in serum and milk, such as the Rose Bengal Test (RBT), Rivanol Test, Serum Agglutination Test (SAT), Milk Ring Test (MRT), 2-Mercaptoethanol Test (2-ME), Complement Fixation Test (CFT), the Fluorescence Polari zation Assay (FPA), Buffered Acidified Plate Antigen Test (BAPAT), Brucellosis Skin Test (BST), competitive Enzyme-Linked Immunosorbent Assay (c-ELISA), and indirect Enzyme-Linked Immunosorbent Assay (i-ELISA). The direct brucellosis diagnosis methods can be performed by bacterial culture and nucleic acid detection by molecular appro aches such as Real-Time or Quantitative Polymerase Chain Reaction (RT- or QPCR) and Polymerase Chain Reaction (PCR).

Meta-epidemiological analysis of camel brucellosis

The prevalence of camel brucellosis was calculated as a ratio of positive Brucella specimens to the total sample size. Meta-analysis of prevalence was conducted by metaprop command. The I-squared test (I2 index) evaluated the heterogeneity among different studies, and it was verified if the I2 > 50% (Higgins and Thompson, 2002). Furthermore, a random-effects model (REM) calculated the pooled odds ratio (OR) in the studies to investigate the pooled prevalence of camel brucellosi s in exanimated subgroups. Moreover, meta-regression analysis calculated the prevalence of camel brucellosis over time (Jackson et al., 2015; Stanley and Jarrell, 1989). Version 12.0 of the STATA software (STATA Corp, College Station, TX, USA) was used to evaluate the statistical analyses. The findings were investigated as significant when P-values were less than 0.05.

Results

Search results

Our results included 2426 studies dealing with camel brucellosis from different databases of CABI (n = 143), PubMed (n = 504), Web of Science (n = 311), Cochrane (n = 209), Scielo (n = 148), Embase (n = 297), Scopus (n = 621) and Science Direct (n = 193) (Figure 1). We analyzed 56 articles with 205 data reports based on the exclusion and inclusion rules. Articles published between 1 January 1980 and 1 April 2021 were included in the analysis (Figure 2). A total of 56 articles were acceptable and complied with the selection criteria. All eligible data listed in the “data extraction” section are available in Supplementary file 1.

Figure 2. Distribution of the number of studies on the prevalence of Brucella spp. in camels over time.

Geographical distribution of relevant studies in camel

The results of 56 articles (205 studies with a sample size of 134,949) (Figure 1) revealed that the number of studies investigating the occurrence of camel brucellosis in different regions varied from 46 studies in Egypt to one study in Niger (Table 1). In addition, the highest number of studies (n = 22) on camel brucellosis was observed in 2015 (Figure 2). However, no studies have focused on camel brucellosis in some countries such as Mauritania, Chad, Djibouti (countries with a high camel population), and Qatar and South Morocco (countries with an extremely high population of camels). The lowest and highest prevalence of camel brucellosis were observed in Oman (0.34%, 95%CI: 0.18–0.55) and Sudan (37.41%, 95%CI: 25.27–50.31), respectively (Table 1 and Figures 3 and 4).

Table 1. Meta-analysis of the prevalence of Brucella infection in camels by country.

Country Number study ES* Lower Upper Weight (%) Heterogeneity statistic Degrees of freedom P value I2
Sudan 23 37.41 25.27 50.31 10.61 7453.22 22 <0.001 99.70%
Saudi Arabia 9 13.32 9.24 17.97 4.40 89.05 8 <0.001 91.02%
Jordan 9 12.25 9.34 15.46 4.34 33.43 8 <0.001 76.07%
Nigeria 6 11.21 9.29 13.28 3.06 1.73 5 0.88 0.00%
Egypt 46 11.93 9.33 16.97 22.74 236.45 45 <0.001 94.32%
Kuwait 4 10.93 7.50 14.81 1.84 9.38 3 0.02 68.01%
Mongolia 3 9.24 1.18 23.51 1.55 . 2 . .%
Kenya 4 8.29 5.76 11.21 2.03 4.25 3 0.24 29.49%
Iran 22 5.75 3.25 8.81 10.93 635.96 21 <0.001 96.70%
Iraq 9 5.20 1.19 11.18 4.33 102.9 8 <0.001 92.23%
United Arab Emirates 10 4.98 2.82 7.67 5.13 595.27 9 <0.001 98.49%
India 6 3.66 0.09 10.13 2.57 15.31 5 0.01 67.33%
Somaliland 2 3.52 2.83 4.28 1.04 . 1 . .%
Yemen 3 3.02 0.00 10.41 1.46 . 2 . .%
Ethiopia 26 2.84 2.17 3.60 13.42 210.69 25 <0.001 88.13%
Libya 5 2.64 1.08 4.69 2.44 7.43 4 0.11 46.14%
Somalia 2 0.97 0.65 1.36 1.04 . 1 . .%
Niger 1 0.76 0.16 2.20 0.52 . 0 . .%
Pakistan 11 0.43 0.00 1.73 5.01 33.12 10 <0.001 69.80%
Oman 3 0.34 0.18 0.55 1.56 . 2 . .%
Overall 64 9.23 7.24 11.41 100.00 30260.3 203 0 100.00%

*Effect size (EF): Pooled prevalence of Brucellainfection.

Figure 3. Spatial distribution of the number of studies on the prevalence of Brucella spp. in camels.

Figure 4. Spatial distribution of the prevalence of Brucella spp. in camels.

Diagnostic methods

Table 2 showed that RBT (n = 50) and CFT (n = 43) were the most used tests for the diagnosis of camel brucellosis, followed by c-ELISA (n = 22), bacterial culture (n = 20), SAT (n = 19), PCR-based methods (n = 25), MRT (n = 5), 2-ME (n = 2), and i-ELISA (n = 2). The lowest and highest prevalence rates were reported by the MRT (3.46%) and the FPA (79.33%), respectively (Table 2). However, our results showed remarkable differences between the prevalence of camel brucellosis obtained through direct methods (15.08%) and indirect methods (8.49%) (Table 2).

Prevalence rates based on sample types and sampling methods

The biological specimens used for Brucella investigation in camels were, in the vast majority of cases, blood samples (n = 165 studies), followed by milk (n = 18 studies), lymph node (n = 13 studies), aborted fetus (n = 4 studies), vaginal swab (n = 3 studies), and semen (n = 1 study), while other samples, including abomasum contents (fetuses), and testes were not investigated (Table 2). Of note, testes were analyzed after experimental infection with B. abortus wild-type (n = 1) and B. abortus S19) vaccine (n = 5) but no Brucella strain has been isolated from these samples (Damir et al., 1989). Not surprisingly, aborted fetuses showed a higher prevalence of Brucella spp. with 29.23% when compared to those reported in lymph nodes (21.45%), vaginal swabs (9.54%), blood samples (8.60%), milk (8.30%), and semen (2.13%). In most studies, sampling was done among apparently healthy camels (in 155 out of 195 studies). Coherently, the prevalence of camel brucellosis was higher in animals with apparent symptoms such as wry neck syndrome (50%), knee hygroma (37.17%), arthritis (33.33%), abortion (7.74%), and the lowest rates of brucellosis were showed among animals with infertility (1.54%) (Table 3).

Table 2. Meta-analysis of the prevalence of Brucella infection in camels by Samples tissue, Gender, Biovar, Symptoms, and D/I Subgroups.

Subgroup Number study Pooled Lower Upper Weight (%) Heterogeneity statistic Degrees of freedom P value I2
Samples tissue Fetus 4 29.23 0.67 71.25 1.59 42.69 3 <0.001 92.97%
Lymph node 13 21.45 9.48 36.02 5.57 217.6 12 <0.001 94.49%
Vaginal swab 3 9.54 0.00 30.71 1.37 . 2 . .%
Blood 165 8.60 6.51 10.92 82.57 29863.17 164 <0.001 99.45%
Milk 18 8.30 5.12 12.04 8.41 74.88 17 <0.001 77.30%
Semen 1 2.13 0.26 7.48 0.50 . 0 . .%
Gender Female 62 9.64 6.73 12.93 29.34 1489.83 61 <0.001 95.91%
Male 41 6.83 3.86 10.39 19.12 1967.32 40 <0.001 97.97%
Biovar B.m3 11 12.06 8.81 15.66 5.02 44.86 10 <0.001 77.71%
B.m1 7 3.4 0.46 8.05 3.32 61.97 6 <0.001 90.32%
B.m2 2 8.92 7.8 10.12 1.02 . 1 . .%
B.a6 2 71.88 34.68 98.58 0.55 . 1 . .%
B.a3 1 14.58 8.21 23.26 0.5 . 0 . .%
B.a5 1 3.13 0.65 8.86 0.5 . 0 . .%
Symptoms Wry neck syndrome 1 50 11.81 88.19 0.31 . 0 . .%
Knee hygroma 2 37.17 4.76 76.08 0.53 . 1 . .%
Arthritis 1 33.33 4.33 77.72 0.31 . 0 . .%
Orchitis 2 33.33 0.24 79.48 0.47 . 1 . .%
Healthy animal 155 9.92 7.6 12.49 77.63 23451.36 154 <0.001 99.34%
Abortion 32 7.74 5.21 10.64 15.28 402.75 31 <0.001 92.30%
Infertility 3 1.54 0.71 2.62 1.53 . 2 . .%
D/I D 37 15.08 5.93 26.88 16.84 2638.84 36 <0.001 98.64%
I 167 8.49 6.5 10.7 83.16 26925.84 166 <0.001 99.38%

Table 3. Meta-analysis of the prevalence of Brucella infection in camels by the detection method.

Method of detection Number study Pooled Lower Upper Weight (%) Heterogeneity statistic Degrees of freedom P value I2
FPA 1 79.33 76.53 81.94 0.52 . 0 . .%
BST 1 42.65 30.72 55.23 0.49 . 0 . .%
Culture 20 17.04 9.14 26.42 8.53 246.24 19 <0.001 92.28%
RT-PCR 7 15.01 0 50.9 3.53 1327.15 6 <0.001 99.55%
c-ELISA 22 13.41 5.81 23.27 10.96 2894.43 21 <0.001 99.27%
BAPAT 5 10.65 9.22 12.17 2.54 4.04 4 0.4 0.97%
PCR 18 9.47 5.67 14.04 8.78 145.82 17 <0.001 88.34%
Rivanol Test 2 8.72 6.79 10.86 1.02 . 1 . .%
RBT 50 8.57 5.44 12.24 24.45 6465.73 49 <0.001 99.24%
SAT 19 8.16 1.95 17.25 9.06 2630.17 18 <0.001 99.32%
i-ELISA 8 7.81 3.25 13.99 4.05 145.38 7 <0.001 95.18%
CFT 43 5.06 3.06 7.52 22.13 5227.08 42 <0.001 99.20%
2-ME 2 4.08 0 15.16 1.54 . 2 . .%
MRT 5 3.46 0.9 7.16 2.38 8.91 4 0.06 55.08%

FPA: Fluorescence Polarization Assay; BST: Brucellosis Skin Test; RT-PCR: Real-Time Polymerase Chain Reaction; c-ELISA: competitive Enzyme-Linked Immunosorbent Assay; BAPAT: Buffered Acidified Plate Antigen Test; PCR: Polymerase Chain Reaction; RBT: Rose Bengal Test; SAT: Serum Agglutination Test; i-ELISA: indirect Enzyme-Linked Immunosorbent Assay; CFT: Complement Fixation Test; 2-ME: 2-Mercaptoethanol Test; Rivanol test; MRT: Milk Ring Test.

Overall brucellosis prevalence according to the gender of camel

This meta-analysis reported remarkable differences between the prevalence of camel brucellosis in females (9.64% among 62 studies) and males (6.83% in 41 studies). The gender of exanimated camels was not reported in 102 studies (Table 2).

Most prevalent Brucella spp. infecting camel

Although the isolation of B. melitensis (n = 29), B. abortus (n = 22), and Brucella suis (n = 1) from camel was reported in different investigations, the species level of Brucella isolates was not reported in 153 studies. Among identified Brucella spp., B. abortus biovar 6 showed the highest prevalence rate (71.88%), followed by B. abortus biovar 3 (14.58%), B. melitensis biovar 3 (12.06%), B. melitensis biovar 2 (8.92%), B. melitensis biovar 1 (3.4%), and B. abortus biovar 5 (3.13%). In some studies (n = 27), the biovar of Brucella spp. was not reported (prevalence rate of 10.26%)

Risk factor analysis of camel brucellosis

The risk factors, including geographical location, sex, herd size, age, and mixed rearing with other animals, can be considered the main risk factors for brucellosis in camels (Figure 5). Among data reports investigating the association between location and the occurrence of camel brucellosis, 60 reported a positive (n = 33) or negative (n = 27) association, whereas others found no evidence of a significant association (n = 145). Thirty-three studies have reported the effects of sex as a significant risk for brucellosis. Although the results of studies investigating the association between herd size and camel brucellosis were discording, most studies found a significant association (29 significant vs. 10 nonsignificant reports). Eighteen studies evaluating the effects of age reported an increased risk of brucellosis with greater age. Furthermore, several studies reported a significant association of mix herding/rearing with other livestock species and camel brucellosis (n = 39), although other studies showed a nonsignificant association (n = 10). Abortion history was only evaluated in 10 studies of the evaluated risk factors. Significant and insignificant associations were found in four and six studies, respectively.

Figure 5. Effective risk factors of Brucellosis in camels that considered in research studies.

Discussion

Brucellosis is a severe zoonotic disease in camel-rearing countries with serious economic consequences (Abbas and Agab, 2002; Gwida et al., 2012). Considering the close relationship between camels and humans, camel brucellosis should be an important public health issue (Alamian and Dadar, 2019; Dadar and Alamian, 2020; Sprague et al., 2012). Nevertheless, brucellosis in camels remains a neglected disease with low attention from health authorities and scientists. Since the first report of camel brucellosis in 1931 (Solonitsuin, 1949), the disease has been reported in all camel-raising areas worldwide. Although mixed herding with other livestock species was reported as a significant risk factor for camel brucellosis in 39 studies, no such association was seen in 10 studies. In this regard, Musa and his colleagues showed that cattle were a possible source of camel brucellosis because of the negative brucellosis results of all small ruminants screened in their study (Musa et al., 2008). In another study, close contact with small ruminants and cattle climbed to over 2.3 and 3.6 times the seropositivity of Brucella spp (Hadush et al., 2013). Our findings showed that the prevalence of camel brucellosis varied for different camel-rising countries over time. There are also significant differences in diagnostic tests, regional breeding technology, agro-ecology of camel-rising countries, husbandry and management systems, absence of adequate veterinary service, large-scale animal grazing, sharing of grazing pasture with other livestock species, lack of awareness about camel brucellosis, continuous movement of infected animals into a susceptible herd, cohabitation with other ruminants, as well as sanitation conditions (Abdelgawad et al., 2017; Gwida et al., 2012; Mokhtar et al., 2007; Sprague et al., 2012). In addition, illegal animal movement, unreported outbreaks, communal clashes, and the absence of brucellosis control programs in different regions are often combined factors contributing to the maintenance and establishment of camel brucellosis.

In some developing countries, the proportion of camels infected by Brucella spp. is relatively large because camel herds suffer from a lack of appropriate surveillance programs. Furthermore, the control of camel brucellosis is severely hampered in camel-raising countries (Sprague et al., 2012). Therefore, several strategies should be used to improve the situation of camel brucellosis and significantly decrease the occurrence of the disease, including encouragement of animal keepers for closer interaction with the veterinary organization and awareness about camel brucellosis and sustainable control approaches. In some countries, no or only a few studies have been performed, thereby stressing the need for further investigation into camel populations.

Our analysis shows that geographical location, sex, herd size, age, and mixed rearing are important risk factors for brucellosis in camels. Several studies showed a higher prevalence of brucellosis among adult camels >4 years old compared to 6 months to 4-year-old animals (Dawood, 2008; Khan et al., 2020; Salisu et al., 2018). Among the risk factors evaluated in camel brucellosis in Ethiopia, body condition and abortion showed a statistically significant difference concerning the seropositivity of camel brucellosis (Waktole et al., 2022). The seroprevalence and associated risk factors for camel brucellosis in Algeria showed a higher seroprevalence in animals living in flocks with a history of abortion and females (P = 0.01) (Benfodil et al., 2022). Moreover, it has been shown that the seroprevalence of brucellosis obtained by i-ELISA was 22.9% in the age group lower than 8 years, 27.9% in animals aged 8–11 years, and 25.7% among camels aged 13–15 years (Khan et al., 2020). In another study, the seroprevalence of camel brucellosis using RBT was remarkably higher (29.4%) in the 5–9 year age group compared to 0–4 ones (8%) (Abebe et al., 2017). The seroprevalence in females (9.64%) was significantly higher than in males (6.83%). Previous data show that females with a history of abortion reported a higher prevalence of camel brucellosis followed by pregnant and nonpregnant females (Fatima et al., 2016). Other studies also showed the antibodies of Brucella as frequently detected in males (7%) compared to females (8.3%) (Kudi et al., 1997). Such high seropositive rates in males may be related to the fact that the main populations of imported camels for slaughter are males (Khan et al., 2020). Therefore, abattoir surveys may have an important selection bias, and inferences about the local population must be made with caution. It has been suggested that female camels can transmit the infection to other livestock species by vaginal mucous, aborted fetuses, and milk (Al-Majali et al., 2008; Dadar et al., 2020). Limited data on aborted fetuses showed a high prevalence (29.23%), suggesting high prevalence and transmission rates in pregnant animals during the last 4 months of pregnancy (Al-Majali et al., 2008). Another study also highlighted that rearing camels with other ruminants were significantly associated with camel brucellosis (Fatima et al., 2016). Moreover, camel herds with more than 30 animals were more sustainable for brucellosis seropositivity (Ghanem et al., 2009). Mixed husbandry systems were associated with seropositive brucellosis camel herds (Ghanem et al., 2009). However, some reported risk factors, such as age, sex, breed, mixed herds, and locality, were unrelated in some studies (Khan et al., 2020; Ullah et al., 2015). Therefore, there is high demand for enrolment in control programs and increasing public health knowledge to prevent camel brucellosis. The RBT is a cost-effective and easy-to-use test that shows specific specificity and sensibility values, especially in endemic areas for camel brucellosis (Gwida et al., 2011). However, some nonspecific agglutination could occur due to the interference with nonspecific antibodies reported in other livestock species (OIE) and humans in endemic areas (Díaz et al., 2011). The CFT was used in different studies and compared favorably with other serological tests like the SAT that the OIE approves for the serological identification of brucellosis in livestock (Gwida et al., 2011; Sprague et al., 2012). The c-ELISA and i-ELISA have also been applied to detect anti-Brucella antibodies in camels. According to Gwida et al. (2011), the c-ELISA detected the lowest number of positive cases (68.8%) compared to the RBT (70.7%), the SAT (70.6%), the CFT (71.4%), and the FPA (79.3%). Another study also showed seroprevalence of camel brucellosis in south Algeria as 5.3 and 1.4% through the ELISA test and RBPT, respectively (Benfodil et al., 2022). The tests of RBT and CFT were also used as screening and confirmatory methods of camel brucellosis seroepidemiology in Ethiopia (Waktole et al., 2022). Tests that are not widely used are the FPA and the BST, both reported in one study. Our results suggest fewer clinical signs in Brucella-infected camels than in other ruminant animals. Indeed, 155 studies reported camel brucellosis in apparently healthy animals, and only 32 studies reported an abortion history in the herd. Other signs such as wry neck syndrome, knee hygroma, arthritis, orchitis, and infertility were also reported in some studies (Gutema and Tesfaye, 2019; Hussein, 2021; Musa et al., 2008). However, Musa and his colleagues showed no significant link between the wry neck syndrome in camels with brucellosis, although repeated abortion, hygroma, and arthritis were associated with the disease occurrence (Musa et al., 2008). Raising public awareness and education about the zoonotic importance of camel brucellosis, proper hygienic practices, control of risk factors, and multidisciplinary work between health and veterinary personnel should be improved (Admasu and Kaynata, 2017). Our research has limitations, such as a few studies on camel brucellosis in African countries such as Mauritania, Chad, and Djibouti (countries with a high population of camel livestock), Qatar, and South Morocco. The small sample size of camels in some studies made it difficult to determine the true prevalence of camel brucellosis in any specific locality.

Data related to the epidemiology of brucellosis in Bactrian camels have been reported infrequently in the international literature (Bayasgalan et al., 2018; Kim et al., 2016). Both studies were performed in Mongolia and suggested that Bactrian camels are secondary hosts for Brucella spp. A relevance between the seropositivity of cattle and camel, but not small ruminants, was described in different studies. The fact that Brucella isolates in camels were B. abortus further support an association between brucellosis in camels and cattle in Mongolia (Bayasgalan et al., 2018; Damir et al., 1989). Finally, it should be highlighted that there is an important knowledge gap related to anti-brucellosis vaccination in camels. Field data are sparse and often lack validation, while vaccine safety and efficacy have not been studied experimentally. Currently, there is no vaccine registered for use in camels, and thus vaccination is not recommended by the OIE.

Conclusion

Our knowledge of brucellosis in camels has increased over the last decade through comprehensive laboratory diagnosis, field analysis, and experimental infection trials. Infection with B. abortus and B. melitensis is frequent in different countries. The overall prevalence of camel brucellosis worldwide was 9.23%. The lack of prevention and control programs could make it a public health threat for the pastoral community. The highest incidence is when camels are kept together with infected small ruminants and bovines. A combination of direct methods and indirect methods can detect all positive reactors. However, isolation of the bacteria is still the golden test, although several molecular-based methods have been improved. Currently, no anti-brucellosis vaccine is recommended for use in camels by the OIE. Questions about the implementation of vaccination and the safety and efficacy of anti-Brucella vaccines in camels remain entirely open in endemic areas.

Funding

The current research was funded by Food Health Research Center, Hormozgan University of Medical Sciences, Bandar Abbas, Iran (IR.HUMS.REC.1400.239).

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Supplementary file 1

Table S1. Main characteristic included in our study.

Author Start End Location Animal species No sample Positive Method D/i Sample Isolate Blovar Gender Symptom Location Sex Herd size Age Abortion history Mix rearing Title
Zowghi 1986 1987 Iran Camelus dromedarius 953 77 CFT I Blood Brucella melitensis 3 ND Healthy animal ND ND ND ND ND ND Brucellosis in camels in Iran (Zowghi and Ebadi, 1989)
Zowghi 1986 1987 Iran Camelus dromedarius 300 3 Culture D Lymph node Brucella melitensis 1 ND Healthy animal ND ND ND ND ND ND Brucellosis in camels in Iran (Zowghi and Ebadi, 1989)
Al-Khalaf 1986 1986 Kuwait Camelus dromedarius 698 104 CFT I Blood Brucella spp ND ND Abortion ND ND ND ND ND ND Brucellosis of camels in Kuwait (Al-Khalaf and El-Khaladi, 1989)
Al-Khalaf 1986 1986 Kuwait Camelus dromedarius 698 91 SAT I Blood Brucella spp ND ND Abortion ND ND ND ND ND ND Brucellosis of camels in Kuwait (Al-Khalaf and El-Khaladi, 1989)
Al-Khalaf 1986 1986 Kuwait Camelus dromedarius 209 17 MRT I Milk Brucella spp ND ND Abortion ND ND ND ND ND ND Brucellosis of camels in Kuwait (Al-Khalaf and El-Khaladi, 1989)
Al-Khalaf 1986 1986 Kuwait Camelus dromedarius 5 2 Culture D Fetus Brucella abortus ND ND Abortion ND ND ND ND ND ND Brucellosis of camels in Kuwait (Al-Khalaf and El-Khaladi, 1989)
Bornstein 1987 1987 Sudan Camelus dromedarius 102 7 SAT I Blood Brucella abortus ND ND Healthy animal ND ND ND ND ND ND Prevalence of antibodies due to some viral pathogens, Brucella abortus, and Toxoplasma gondii in serum from camels (Camelus dromedarius) in Sudan (Bornstein and Musa, 1987)
Bornstein 1987 1987 Sudan Camelus dromedarius 102 7 CFT I Blood Brucella abortus ND ND Healthy animal ND ND ND ND ND ND Prevalence of antibodies due to some viral pathogens, Brucella abortus, and Toxoplasma gondii in serum from camels (Camelus dromedarius) in Sudan (Bornstein and Musa, 1987)
Radwan 1989 1991 Saudi Arabia Camelus dromedarius 2630 212 RBT I Blood Brucella melitensis 1 ND Healthy animal ND ND ND ND ND ND Serological and bacteriological study of brucellosis in camels in central Saudi Arabia(Radwan et al., 1992)
Radwan 1989 1991 Saudi Arabia Camelus dromedarius 44 4 RBT I Blood Brucella melitensis 1 ND Healthy animal ND ND ND ND ND ND Serological and bacteriological study of brucellosis in camels in central Saudi Arabia. (Radwan et al., 1992)
Radwan 1989 1991 Saudi Arabia Camelus dromedarius 2283 195 RBT I Blood Brucella melitensis 2 ND Healthy animal ND ND ND ND ND ND Serological and bacteriological study of brucellosis in camels in central Saudi Arabia (Radwan et al., 1992)
Radwan 1989 1991 Saudi Arabia Camelus dromedarius 100 26 Culture I Milk Brucella melitensis 2 Female Healthy animal ND ND ND ND ND ND Serological and bacteriological study of brucellosis (Gameel et al., 1993) in camels in central Saudi Arabia (Radwan et al., 1992)
Gameel 1990 1991 Libya Camelus dromedarius 967 39 SAT I Blood Brucella spp ND ND Healthy animal ND ND ND ND ND ND Prevalence of camel brucellosis in Libya (Gameel et al., 1993)
Gameel 1990 1991 Libya Camelus dromedarius 124 5 Culture D Milk Brucella melitensis 1 Female Abortion ND S ND ND ND ND Prevalence of camel brucellosis in Libya (Gameel et al., 1993)
Gameel 1990 1991 Libya Camelus dromedarius 124 3 Culture D Fetus Brucella melitensis 1 Female Abortion ND S ND ND ND ND Prevalence of camel brucellosis in Libya (Gameel et al., 1993)
Gameel 1990 1991 Libya Camelus dromedarius 124 1 Culture D Vaginal swab Brucella melitensis 1 Female Abortion ND S ND ND ND ND Prevalence of camel brucellosis in Libya (Gameel et al., 1993)
Moustafa 1990 1991 United Arab Emirates Camelus dromedarius 1794 4 CFT I Blood Brucella spp ND ND ND ND ND ND ND ND ND Surveillance of Brucella antibodies in camels of the eastern region of Abu Dhabi, United Arab Emirates (Moustafa et al., 1998)
Moustafa 1991 1992 United Arab Emirates Camelus dromedarius 11323 26 CFT I Blood Brucella spp ND ND ND ND ND ND ND ND ND Surveillance of Brucella antibodies in camels of the eastern region of Abu Dhabi, United Arab Emirates (Moustafa et al., 1998)
Moustafa 1992 1993 United Arab Emirates Camelus dromedarius 1900 7 CFT I Blood Brucella spp ND ND ND ND ND ND ND ND ND Surveillance of Brucella antibodies in camels of the eastern region of Abu Dhabi, United Arab Emirates (Moustafa et al., 1998)
Baumann 1992 1992 Somalia Camelus dromedarius 1539 30 SAT I Blood Brucella spp ND ND Healthy animal S ND S ND ND S Productivity and health of camels (Camelus dromedarius) in Somalia: associations with trypanosomosis and brucellosis (Baumann and Zessin, 1992)
Baumann 1992 1992 Somalia Camelus dromedarius 1539 5 CFT I Blood Brucella spp ND ND Healthy animal S ND S ND ND S Productivity and health of camels (Camelus dromedarius) in Somalia: associations with trypanosomosis and brucellosis (Baumann and Zessin, 1992)
Moustafa 1993 1994 United Arab Emirates Camelus dromedarius 1433 3 CFT I Blood Brucella spp ND ND ND ND ND ND ND ND ND Surveillance of Brucella antibodies in camels of the eastern region of Abu Dhabi, United Arab Emirates (Moustafa et al., 1998)
Moustafa 1994 1995 United Arab Emirates Camelus dromedarius 3145 3 CFT I Blood Brucella spp ND ND ND ND ND ND ND ND ND Surveillance of Brucella antibodies in camels of the eastern region of Abu Dhabi, United Arab Emirates (Moustafa et al., 1998)
Moustafa 1995 1996 United Arab Emirates Camelus dromedarius 7899 8 CFT I Blood Brucella spp ND ND ND ND ND ND ND ND ND Surveillance of Brucella antibodies in camels of the eastern region of Abu Dhabi, United Arab Emirates (Moustafa et al., 1998)
Khadjeh 1997 1997 Iran Camelus dromedarius 258 5 SAT I Blood Brucella spp ND ND ND ND ND ND ND ND ND Incidence of brucellosis in one-humped camels of Boushehr, Iran (Khadjeh et al., 1999)
Khadjeh 1997 1997 Iran Camelus dromedarius 5 3 Culture D Lymph node Brucella melitensis 1 Female ND ND ND ND ND ND ND Incidence of brucellosis in one-humped camels of Boushehr, Iran (Khadjeh et al., 1999)
Teshome 2000 2001 Ethiopia Camelus dromedarius 1442 82 RBT I Blood Brucella spp ND ND Healthy animal NS NS ND ND ND ND A seroprevalence study of camel brucellosis in three camel-rearing regions of Ethiopia (Teshome et al., 2003)
Teshome 2000 2001 Ethiopia Camelus dromedarius 1442 60 CFT I Blood Brucella spp ND ND Healthy animal NS NS ND ND ND ND A seroprevalence study of camel brucellosis in three camel-rearing regions of Ethiopia (Teshome et al., 2003)
Teshome 2000 2001 Ethiopia Camelus dromedarius 282 12 CFT I Blood Brucella spp ND ND Healthy animal NS NS ND ND ND ND A seroprevalence study of camel brucellosis in three camel-rearing regions of Ethiopia (Teshome et al., 2003)
Teshome 2000 2001 Ethiopia Camelus dromedarius 1157 48 CFT I Blood Brucella spp ND ND Healthy animal NS NS ND ND ND ND A seroprevalence study of camel brucellosis in three camel-rearing regions of Ethiopia (Teshome et al., 2003)
Omer 2000 2000 Ethiopia Camelus dromedarius 98 3 CFT I Blood Brucella spp ND ND Healthy animal ND ND S ND ND S Prevalence of antibodies to Brucella spp. in cattle, sheep, goats, horses, and camels in the State of Eritrea; influence of husbandry systems (Omer et al., 2000)
Omer 2000 2000 Ethiopia Camelus dromedarius 98 3 RBT I Blood Brucella spp ND ND Healthy animal ND ND S ND ND S Prevalence of antibodies to Brucella spp. in cattle, sheep, goats, horses, and camels in the State of Eritrea; influence of husbandry systems (Omer et al., 2000)
Hamdy 2002 2002 Egypt Camelus dromedarius 12 1 RBT I Milk Brucella spp ND Female Healthy animal ND ND ND ND ND ND Detection of Brucella species in the milk of infected cattle, sheep, goats and camels by PCR(Hamdy and Amin, 2002)
Hamdy 2002 2002 Egypt Camelus dromedarius 12 1 SAT I Milk Brucella spp ND Female Healthy animal ND ND ND ND ND ND Detection of Brucella species in the milk of infected cattle, sheep, goats, and camels by PCR (Hamdy and Amin, 2002)
Hamdy 2002 2002 Egypt Camelus dromedarius 12 1 MRT I Milk Brucella spp ND Female Healthy animal ND ND ND ND ND ND Detection of Brucella species in the milk of infected cattle, sheep, goats and camels by PCR (Hamdy and Amin, 2002)
Hamdy 2002 2002 Egypt Camelus dromedarius 12 1 PCR D Milk Brucella spp ND Female Healthy animal ND ND ND ND ND ND Detection of Brucella species in the milk of infected cattle, sheep, goats, and camels by PCR (Hamdy and Amin, 2002)
FRANCK 2002 2002 Niger Camelus dromedarius 395 3 c-ELISA I Blood Brucella spp ND ND Healthy animal S ND ND S ND ND Prevalence of brucellosis in camels (camelus dromedarius) in northern Niger (Franck et al.)
Musa 2002 2002 Sudan Camelus dromedarius 4 1 SAT I Blood Brucella spp ND Male Knee hygroma ND ND ND ND ND S Brucellosis in camels (Camelus dromedarius) in Darfur, western Sudan (Musa and Shigidi, 2001)
Musa 2002 2002 Sudan Camelus dromedarius 4 2 RBT I Blood Brucella spp ND Male Knee hygroma ND ND ND ND ND S Brucellosis in camels (Camelus dromedarius) in Darfur, western Sudan(Musa and Shigidi, 2001)
Musa 2002 2002 Sudan Camelus dromedarius 17 3 SAT I Blood Brucella spp ND Female Abortion ND ND ND ND ND S Brucellosis in camels (Camelus dromedarius) in Darfur, western Sudan (Musa and Shigidi, 2001)
Musa 2002 2002 Sudan Camelus dromedarius 6 2 Culture D Lymph node Brucella melitensis 3 Female Arthritis ND ND ND ND ND S Brucellosis in camels (Camelus dromedarius) in Darfur, western Sudan (Musa and Shigidi, 2001)
Musa 2002 2002 Sudan Camelus dromedarius 6 3 Culture D Lymph node Brucella abortus 6 Female Wry neck syndrome ND ND ND ND ND S Brucellosis in camels (Camelus dromedarius) in Darfur, western Sudan (Musa and Shigidi, 2001)
Musa 2001 2002 Sudan Camelus dromedarius 993 72 SAT I Blood Brucella spp ND Male Healthy animal ND ND ND ND ND ND Implications in abortion and early-life infection= La brucellose chez les dromadaires en zones d’élevage intensif au Soudan (Musa and Shigidi, 2001)
Musa 2001 2002 Sudan Camelus dromedarius 2420 196 CFT I Blood Brucella spp ND Female Healthy animal ND ND ND ND ND ND Implications in abortion and early-life infection= La brucellose chez les dromadaires en zones d’élevage intensif au Soudan (Musa and Shigidi, 2001)
Musa 2001 2002 Sudan Camelus dromedarius 306 51 CFT I Blood Brucella spp ND Female Abortion ND ND ND ND ND ND Implications in abortion and early-life infection= La brucellose chez les dromadaires en zones d’élevage intensif au Soudan (Musa and Shigidi, 2001)
Musa 2001 2002 Sudan Camelus dromedarius 110 3 MRT I Milk Brucella spp ND Female Abortion ND ND ND ND ND ND Implications in abortion and early-life infection= La brucellose chez les dromadaires en zones d’élevage intensif au Soudan(Musa and Shigidi, 2001)
Megersa 2003 2004 Ethiopia Camelus dromedarius 3218 58 CFT I Blood Brucella spp ND ND Healthy animal ND S S S ND ND Seroprevalence of brucellosis in camels (Camelus dromedarius) in Borena Lowland, Southern Ethiopia (Megersa et al., 2005)
Megersa 2003 2004 Ethiopia Camelus dromedarius 3218 58 RBT I Blood Brucella spp ND ND Healthy animal ND S S S ND ND Seroprevalence of brucellosis in camels (Camelus dromedarius) in Borena Lowland, Southern Ethiopia (Megersa et al., 2005)
Moghney 2004 2004 Egypt Camelus dromedarius 679 59 RBT I Blood Brucella spp ND ND Healthy animal ND ND ND ND ND ND A preliminary study on brucellosis on camels at Behira province (Moghney, 2004)
Moghney 2004 2004 Egypt Camelus dromedarius 679 60 SAT I Blood Brucella spp ND ND Healthy animal ND ND ND ND ND ND A preliminary study on brucellosis on camels at Behira province (Moghney, 2004)
Moghney 2004 2004 Egypt Camelus dromedarius 679 61 Rivanol test I Blood Brucella spp ND ND Healthy animal ND ND ND ND ND ND A preliminary study on brucellosis on camels at Behira province(Moghney 2004)
Moghney 2004 2004 Egypt Camelus dromedarius 679 55 2-ME I Blood Brucella spp ND ND Healthy animal ND ND ND ND ND ND A preliminary study on brucellosis on camels at Behira province (Moghney, 2004)
Moghney 2004 2004 Egypt Camelus dromedarius 679 64 Buffered Acidified Plate Antigen Test I Blood Brucella spp ND ND Healthy animal ND ND ND ND ND ND A preliminary study on brucellosis on camels at Behira province (Moghney, 2004)
Moghney 2004 2004 Egypt Camelus dromedarius 679 62 i-ELISA I Blood Brucella spp ND ND Healthy animal ND ND ND ND ND ND A preliminary study on brucellosis on camels at Behira province (Moghney, 2004)
Moghney 2004 2004 Egypt Camelus dromedarius 87 8 RBT I Blood Brucella spp ND ND Healthy animal ND ND ND ND ND S A preliminary study on brucellosis on camels at Behira province (Moghney, 2004)
Moghney 2004 2004 Egypt Camelus dromedarius 87 8 SAT I Blood Brucella spp ND ND Healthy animal ND ND ND ND ND S A preliminary study on brucellosis on camels at Behira province (Moghney, 2004)
Moghney 2004 2004 Egypt Camelus dromedarius 87 7 Rivanol test I Blood Brucella spp ND ND Healthy animal ND ND ND ND ND S A preliminary study on brucellosis on camels at Behira province (Moghney, 2004)
Moghney 2004 2004 Egypt Camelus dromedarius 87 7 2-ME I Blood Brucella spp ND ND Healthy animal ND ND ND ND ND S A preliminary study on brucellosis on camels at Behira province (Moghney, 2004)
Moghney 2004 2004 Egypt Camelus dromedarius 87 9 Buffered Acidified Plate Antigen Test I Blood Brucella spp ND ND Healthy animal ND ND ND ND ND S A preliminary study on brucellosis on camels at Behira province (Moghney, 2004)
Moghney 2004 2004 Egypt Camelus dromedarius 87 9 i-ELISA I Blood Brucella spp ND ND Healthy animal ND ND ND ND ND S A preliminary study on brucellosis on camels at Behira province (Moghney, 2004)
Al-Majali 2004 2006 Jordan Camelus dromedarius 412 47 RBT I Blood Brucella spp ND ND Healthy animal ND ND S ND ND S Risk factors associated with camel brucellosis in Jordan (Al-Majali et al., 2008)
Al-Majali 2004 2006 Jordan Camelus dromedarius 412 39 CFT I Blood Brucella spp ND ND Healthy animal ND ND S ND ND S Risk factors associated with camel brucellosis in Jordan (Al-Majali et al., 2008)
Al-Majali 2004 2006 Jordan Camelus dromedarius 7 4 Culture D Fetus Brucella melitensis 3 Female Abortion ND S S ND ND S Risk factors associated with camel brucellosis in Jordan (Al-Majali et al., 2008)
Mokhtar 2004 2006 Sudan Camelus dromedarius 14372 2605 RBT I Blood Brucella spp ND ND Healthy animal ND ND ND ND ND ND Survey of Brucellosis among Sheep, Goats, Camels (Mokhtar et al., 2007)
Tilahun 2005 2006 Ethiopia Camelus dromedarius 822 28 RBT I Blood Brucella spp ND ND Healthy animal NS NS NS ND ND NS Camel brucellosis and management practices in Jijiga and Babile districts, Eastern Ethiopia (Tilahun et al., 2013)
Tilahun 2005 2006 Ethiopia Camelus dromedarius 822 20 CFT I Blood Brucella spp ND ND Healthy animal NS NS NS ND ND NS Camel brucellosis and management practices in Jijiga and Babile districts, Eastern Ethiopia (Tilahun et al., 2013)
Tilahun 2005 2006 Ethiopia Camelus dromedarius 641 15 CFT I Blood Brucella spp ND Female Healthy animal NS NS NS ND ND NS Camel brucellosis and management practices in Jijiga and Babile districts, Eastern Ethiopia (Tilahun et al., 2013)
Tilahun 2005 2006 Ethiopia Camelus dromedarius 181 5 CFT I Blood Brucella spp ND Male Healthy animal NS NS NS ND ND NS Camel brucellosis and management practices in Jijiga and Babile districts, Eastern Ethiopia (Tilahun et al., 2013)
Dawood 2006 2007 Jordan Camelus dromedarius 640 91 RBT I Blood Brucella spp ND ND Healthy animal NS NS ND ND ND ND Brucellosis in Camels (Camelus dromedorius) in the south province of Jordan (Dawood, 2008)
Dawood 2006 2007 Jordan Camelus dromedarius 640 79 CFT I Blood Brucella spp ND ND Healthy animal NS NS ND ND ND ND Brucellosis in Camels (Camelus dromedorius) in the south province of Jordan(Dawood, 2008)
Dawood 2006 2007 Jordan Camelus dromedarius 30 13 Culture D Fetus Brucella melitensis 3 Female Abortion NS NS ND ND ND ND Brucellosis in Camels (Camelus dromedorius) in the south province of Jordan (Dawood, 2008)
Dawood 2006 2007 Jordan Camelus dromedarius 26 2 Culture D Milk Brucella melitensis 3 Female Abortion NS NS ND ND ND ND Brucellosis in Camels (Camelus dromedorius) in the south province of Jordan (Dawood, 2008)
Dawood 2006 2007 Jordan Camelus dromedarius 147 11 CFT I Blood Brucella spp ND Male Healthy animal ND ND ND ND ND ND Brucellosis in Camels (Camelus dromedorius) in the south province of Jordan (Dawood, 2008)
Dawood 2006 2007 Jordan Camelus dromedarius 493 68 CFT I Blood Brucella spp ND Female Healthy animal ND ND ND ND ND ND Brucellosis in Camels (Camelus dromedorius) in the south province of Jordan (Dawood, 2008)
Junaidu 2006 2006 Nigeria Camelus dromedarius 141 18 c-ELISA I Blood Brucella spp ND Female Healthy animal ND ND ND ND ND ND Brucellosis in camels (Camelus dromedaries) slaughtered in Sokoto, northwestern Nigeria (Dawood, 2008)
Junaidu 2006 2006 Nigeria Camelus dromedarius 141 18 RBT I Blood Brucella spp ND Female Healthy animal ND ND ND ND ND ND Brucellosis in camels (Camelus dromedaries) slaughtered in Sokoto, northwestern Nigeria (Dawood, 2008)
Junaidu 2006 2006 Nigeria Camelus dromedarius 141 18 SAT I Blood Brucella spp ND Female Healthy animal ND ND ND ND ND ND Brucellosis in camels (Camelus dromedaries) slaughtered in Sokoto, northwestern Nigeria (Dawood, 2008)
Junaidu 2006 2006 Nigeria Camelus dromedarius 188 19 RBT I Blood Brucella spp ND Male Healthy animal ND ND ND ND ND ND Brucellosis in camels (Camelus dromedaries) slaughtered in Sokoto, northwestern Nigeria (Dawood, 2008)
Junaidu 2006 2006 Nigeria Camelus dromedarius 188 19 SAT I Blood Brucella spp ND Male Healthy animal ND ND ND ND ND ND Brucellosis in camels (Camelus dromedaries) slaughtered in Sokoto, northwestern Nigeria (Dawood, 2008)
Junaidu 2006 2006 Nigeria Camelus dromedarius 188 19 c-ELISA I Blood Brucella spp ND Male Healthy animal ND ND ND S ND ND Brucellosis in camels (Camelus dromedaries) slaughtered in Sokoto, northwestern Nigeria (Dawood, 2008)
Ahmed 2006 2008 Libya Camelus dromedarius 14 2 RBT I Blood Brucella spp ND Male Healthy animal ND ND ND ND ND ND Seroprevalence of brucellosis in animal and human populations in the western mountains region in Libya, December 2006-January 2008 (Ahmed et al., 2010)
Omer 2007 2010 Sudan Camelus dromedarius 489 138 c-ELISA I Blood Brucella spp ND Male Healthy animal ND ND ND ND ND ND Brucellosis in camels, cattle, and humans: associations and evaluation of serological tests used for the diagnosis of the disease in certain nomadic localities in Sudan (Omer et al., 2010)
Omer 2007 2010 Sudan Camelus dromedarius 1736 697 c-ELISA I Blood Brucella spp ND Female Healthy animal ND ND ND ND ND ND Brucellosis in camels, cattle, and humans: associations and evaluation of serological tests used for the diagnosis of the disease in certain nomadic localities in Sudan (Omer et al., 2010)
Omer 2007 2010 Sudan Camelus dromedarius 2000 797 RBT I Blood Brucella spp ND ND Healthy animal ND ND ND ND ND ND Brucellosis in camels, cattle, and humans: associations and evaluation of serological tests used for diagnosis of the disease in certain nomadic localities in Sudan (Omer et al., 2010)
Omer 2007 2010 Sudan Camelus dromedarius 2000 809 c-ELISA I Blood Brucella spp ND ND Healthy animal ND ND ND ND ND ND Brucellosis in camels, cattle and humans: associations and evaluation of serological tests used for diagnosis of the disease in certain nomadic localities in Sudan(Omer et al., 2010)
Omer 2007 2010 Sudan Camelus dromedarius 3 3 Culture D Lymph node Brucella abortus 6 Female Abortion ND ND ND ND ND ND Brucellosis in camels, cattle, and humans: associations and evaluation of serological tests used for the diagnosis of the disease in certain nomadic localities in Sudan (Omer et al., 2010)
Megersa 2007 2008 Ethiopia Camelus dromedarius 756 17 CFT I Blood Brucella spp ND ND Abortion ND ND ND ND ND S Seroprevalence of brucellosis and its contribution to abortion in cattle, camel, and goat kept under pastoral management in Borana, Ethiopia (Megersa et al., 2011)
Ghanem 2008 2008 Somaliland Camelus dromedarius 1246 49 RBT I Blood Brucella spp ND ND Healthy animal ND ND S ND ND S Seroprevalence of camel brucellosis (Camelus dromedarius) in Somaliland (Ghanem et al., 2009)
Ghanem 2008 2008 Somaliland Camelus dromedarius 1246 39 i-ELISA I Blood Brucella spp ND ND Healthy animal ND ND S ND ND S Seroprevalence of camel brucellosis (Camelus dromedarius) in Somaliland (Ghanem et al., 2009)
Gwida 2008 2009 Sudan Camelus dromedaries 895 633 RBT I Blood Brucella spp ND ND Healthy animal ND ND ND ND ND ND Comparison of diagnostic tests for the detection of Brucella spp. in camel sera. (Gwida et al., 2011)
Gwida 2008 2009 Sudan Camelus dromedaries 895 632 SAT I Blood Brucella spp ND ND Healthy animal ND ND ND ND ND ND Comparison of diagnostic tests for the detection of Brucella spp. in camel sera. (Gwida et al., 2011)
Gwida 2008 2009 Sudan Camelus dromedaries 895 639 CFT I Blood Brucella spp ND ND Healthy animal ND ND ND ND ND ND Comparison of diagnostic tests for the detection of Brucella spp. in camel sera. (Gwida et al., 2011)
Gwida 2008 2009 Sudan Camelus dromedaries 895 616 c-ELISA I Blood Brucella spp ND ND Healthy animal ND ND ND ND ND ND Comparison of diagnostic tests for the detection of Brucella spp. in camel sera. (Gwida et al., 2011)
Gwida 2008 2009 Sudan Camelus dromedaries 895 710 Fluorescence Polarization Assay I Blood Brucella spp ND ND Healthy animal ND ND ND ND ND ND Comparison of diagnostic tests for the detection of Brucella spp. in camel sera. (Gwida et al., 2011)
Gwida 2008 2009 Sudan Camelus dromedaries 895 759 rt-PCR D Blood Brucella spp ND ND Healthy animal ND ND ND ND ND ND Comparison of diagnostic tests for the detection of Brucella spp. in camel sera. (Gwida et al., 2011)
Mohammed 2009 2010 United Arab Emirates Camelus dromedaries 1008 56 RBT I Blood Brucella spp ND ND Healthy animal S S S ND ND ND Sero-prevalence and epidemiology of brucellosis in camels, sheep and goats in Abu Dhabi Emirate(Mohammed and Shigidy 2013)
Mohammed 2009 2010 United Arab Emirates Camelus dromedaries c-ELISA I Blood Brucella spp ND ND Healthy animal S S S ND ND ND Sero-prevalence and epidemiology of brucellosis in camels, sheep, and goats in Abu Dhabi Emirate (Mohammed and Shigidy, 2013)
Warsame 2010 2011 Ethiopia Camelus dromedaries 285 4 CFT I Blood Brucella spp ND Male infertility S S S ND ND ND Seroprevalence and associated risk factors of camel (Camelus dromedaries) brucellosis in and around Dire Dawa, Ethiopia (Ismail et al., 2012)
Bayasgalan 2010 2011 Mongolia Camelus dromedaries 1822 37 RBT I Blood Brucella abortus ND ND Healthy animal S NS NS NS NS S Risk factors of brucellosis seropositivity in Bactrian camels of Mongolia (Bayasgalan et al., 2018)
Bayasgalan 2010 2011 Mongolia Camelus dromedaries 250 37 Culture D Milk Brucella abortus ND Female Healthy animal S NS NS NS NS S Risk factors of brucellosis seropositivity in Bactrian camels of Mongolia (Bayasgalan et al., 2018)
Bayasgalan 2010 2011 Mongolia Camelus dromedaries 250 37 PCR D Milk Brucella abortus ND Female Healthy animal S NS NS NS NS S Risk factors of brucellosis seropositivity in Bactrian camels of Mongolia (Bayasgalan et al., 2018)
Mohammed 2010 2011 Ethiopia Camelus dromedaries 361 6 CFT I Blood Brucella spp ND Female infertility S S S ND ND ND Seroprevalence and epidemiology of brucellosis in camels, sheep, and goats in Abu Dhabi Emirate (Mohammed and Shigidy, 2013)
Ghorbani 2011 2012 Iran Camelus dromedarius 310 39 RBT I Blood Brucella spp ND ND Healthy animal ND ND ND ND ND ND Comparison of serology, culture, and PCR for the detection of brucellosis in slaughtered camels in Iran (Ghorbani et al., 2013)
Ghorbani 2011 2012 Iran Camelus dromedarius 310 7 SAT I Blood Brucella spp ND ND Healthy animal ND ND ND ND ND ND Comparison of serology, culture, and PCR for the detection of brucellosis in slaughtered camels in Iran (Ghorbani et al., 2013)
Ghorbani 2011 2012 Iran Camelus dromedarius 100 39 Culture I Lymph node Brucella spp ND ND Healthy animal ND ND ND ND ND ND Comparison of serology, culture, and PCR for the detection of brucellosis in slaughtered camels in Iran (Ghorbani et al., 2013)
Ghorbani 2011 2012 Iran Camelus dromedarius 100 9 PCR I Blood Brucella spp ND ND Healthy animal ND ND ND ND ND ND Comparison of serology, culture, and PCR for the detection of brucellosis in slaughtered camels in Iran (Ghorbani et al., 2013)
Gessese 2011 2012 Ethiopia Camelus dromedarius 1500 11 RBT I Blood Brucella spp ND ND Healthy animal NS ND ND NS ND S Seroprevalence of brucellosis in camels (Camelus dromedaries) in South East Ethiopia (Gessese et al., 2014)
Gessese 2011 2012 Ethiopia Camelus dromedarius 1501 8 CFT I Blood Brucella spp ND ND Healthy animal NS ND ND NS ND S Seroprevalence of brucellosis in camels (Camelus dromedaries) in South East Ethiopia (Gessese et al., 2014)
Yawoz 2012 2012 Iraq Camelus dromedarius 60 2 RBT I Blood Brucella spp ND Female Healthy animal ND ND ND ND ND ND A serological study of brucellosis in camels south of Kirkuk (Yawoz et al., 2012)
Yawoz 2012 2012 Iraq Camelus dromedarius 6 0 RBT I Blood Brucella spp ND Male Healthy animal ND ND ND ND ND ND A serological study of brucellosis in camels south of Kirkuk (Yawoz et al., 2012)
Hadush 2013 2013 Ethiopia Camelus dromedarius 1152 58 RBT I Blood Brucella spp ND ND Healthy animal NS NS S ND ND S Seroepidemiology of camel brucellosis in the Afar region of Northeast Ethiopia (Hadush et al., 2013)
Hadush 2013 2013 Ethiopia Camelus dromedarius 342 14 CFT I Blood Brucella spp ND Male Healthy animal NS NS S ND ND S Sero-epidemiology of camel brucellosis in the Afar region of Northeast Ethiopia (Hadush et al., 2013)
Hadush 2013 2013 Ethiopia Camelus dromedarius 810 33 CFT I Blood Brucella spp ND Female Healthy animal NS NS S ND ND S Seroepidemiology of camel brucellosis in the Afar region of Northeast Ethiopia (Hadush et al., 2013)
Khamesipour 2013 2013 Iran Camelus dromedarius 123 5 PCR D Blood Brucella abortus ND Female Healthy animal ND ND ND ND ND ND Molecular study of the prevalence of Brucella abortus and Brucella melitensis in the blood and lymph node samples of slaughtered camels by polymerase chain reaction (PCR) in Iran (Khamesipour et al., 2015)
Khamesipour 2013 2013 Iran Camelus dromedarius 123 3 PCR D Blood Brucella melitensis ND Male Healthy animal ND ND ND ND ND ND Molecular study of the prevalence of Brucella abortus and Brucella melitensis in the blood and lymph node samples of slaughtered camels by polymerase chain reaction (PCR) in Iran (Khamesipour et al., 2015)
Khamesipour 2013 2013 Iran Camelus dromedarius 123 4 PCR D Lymph node Brucella abortus ND Female Healthy animal ND ND ND ND ND ND Molecular study of the prevalence of Brucella abortus and Brucella melitensis in the blood and lymph node samples of slaughtered camels by polymerase chain reaction (PCR) in Iran (Khamesipour et al., 2015)
Khamesipour 2013 2013 Iran Camelus dromedarius 123 2 PCR D Lymph node Brucella melitensis ND Male Healthy animal ND ND ND ND ND ND Molecular study of the prevalence of Brucella abortus and Brucella melitensis in the blood and lymph node samples of slaughtered camels by polymerase chain reaction (PCR) in Iran (Khamesipour et al., 2015)
Khamesipour 2013 2013 Iran Camelus dromedarius 78 14 PCR D Lymph node Brucella abortus ND Male Healthy animal ND ND ND ND ND ND Molecular study of the prevalence of Brucella abortus and (Shome et al., 2013) Brucella melitensis in the blood and lymph node samples of slaughtered camels by polymerase chain reaction (PCR) in Iran (Khamesipour et al., 2015)
Khamesipour 2013 2013 Iran Camelus dromedarius 45 16 PCR D Lymph node Brucella melitensis ND Female Healthy animal ND ND ND ND ND ND Molecular study of the prevalence of Brucella abortus and Brucella melitensis in the blood and lymph node samples of slaughtered camels by polymerase chain reaction (PCR) in Iran (Khamesipour et al., 2015)
Shome 2013 2013 India Camelus dromedarius 78 3 SAT I Blood Brucella spp ND Female Healthy animal ND ND ND ND ND A report of seroprevalence of camel brucellosis in India (Shome et al., 2013)
Shome 2013 2013 India Camelus dromedarius 78 3 RBT I Blood Brucella spp ND Female Healthy animal ND ND ND ND ND A report of seroprevalence of camel brucellosis in India (Shome et al., 2013)
Shome 2013 2013 India Camelus dromedarius 5 0 SAT I Blood Brucella spp ND Male Healthy animal ND ND ND ND ND A report of seroprevalence of camel brucellosis in India (Shome et al., 2013)
Shome 2013 2013 India Camelus dromedarius 5 4 RBT I Blood Brucella spp ND Male Healthy animal ND ND ND ND ND A report of seroprevalence of camel brucellosis in India (Shome et al., 2013)
Shome 2013 2013 India Camelus dromedarius 78 3 i-ELISA I Blood Brucella spp ND Female Healthy animal ND ND ND ND ND A report of seroprevalence of camel brucellosis in India (Shome et al., 2013) (Admasu and Kaynata, 2017)
Shome 2013 2013 India Camelus dromedarius 78 3 i-ELISA I Blood Brucella spp ND Male Healthy animal ND ND ND ND ND A report of seroprevalence of camel brucellosis in India (Shome et al., 2013)
Khamesipour 2013 2014 Iran Camelus dromedarius 135 3 rt-PCR D Blood Brucella abortus ND Male Healthy animal ND ND ND ND ND ND Molecular study of Brucellosis in camels by the use of TaqMan® real-time PCR(Khamesipour et al., 2015)
Khamesipour 2013 2014 Iran Camelus dromedarius 135 4 rt-PCR D Lymph node Brucella melitensis ND Female Healthy animal ND ND ND ND ND ND Molecular study of Brucellosis in camels by the use of TaqMan® real-time PCR (Khamesipour et al., 2015)
Abdel Hafez 2013 2014 Saudi Arabia Camelus dromedarius 53 11 Culture D Milk Brucella melitensis 3 Female Abortion ND ND ND ND ND ND Development of a rapid and specific latex agglutination test for the serodiagnosis of camel brucellosis using a Brucella melitensis periplasmic protein antigen (Abdel Hafez et al., 2015)
Khalafalla 2013 2014 Saudi Arabia Camelus dromedarius 182 48 c-ELISA I Blood Brucella spp ND Female Abortion ND ND ND ND ND ND A study on some reproductive disorders in dromedary camel herds in Saudi Arabia with special references to uterine infections and abortion (Khalafalla et al., 2017)
Khalafalla 2013 2014 Saudi Arabia Camelus dromedarius 11 4 Culture D Vaginal swab Brucella spp ND Female Abortion ND ND ND ND ND ND A study on some reproductive disorders in dromedary camel herds in Saudi Arabia with special references to uterine infections and abortion (Khalafalla et al., 2017)
Khalafalla 2013 2014 Saudi Arabia Camelus dromedarius 88 13 PCR D Blood Brucella spp ND Female Abortion ND ND ND ND ND ND A study on some reproductive disorders in dromedary camel herds in Saudi Arabia with special references to uterine infections and abortion (Khalafalla et al., 2017)
Al-Garadi 2014 2015 Yemen Camelus dromedarius 56 6 Culture D Vaginal swab Brucella spp ND Female Abortion ND ND ND ND ND ND Bacteriological and serological study on brucellosis infection in camel (Camelus dromedaries), Al-Hodeida governorate, Yemen (Al-Garadi et al., 2015)
Al-Garadi 2014 2015 Yemen Camelus dromedarius 100 2 RBT I Blood Brucella spp ND Female Abortion ND ND ND ND ND ND Bacteriological and serological study on brucellosis infection in camel (Camelus dromedaries), Al-Hodeida governorate, Yemen (Al-Garadi et al., 2015)
Al-Garadi 2014 2015 Yemen Camelus dromedarius 39 0 MRT I Milk Brucella spp ND Female Healthy animal ND ND ND ND ND ND Bacteriological and serological study on brucellosis infection in camel (Camelus dromedaries), Al-Hodeida governorate, Yemen (Al-Garadi et al., 2015)
Fatima 2014 2015 Pakistan Camelus dromedarius 3 1 RBT I Blood Brucella spp ND Male Orchitis S S S ND ND S Serological, molecular detection, and potential risk factors associated with camel brucellosis in Pakistan. Tropical animal health and production(Fatima et al., 2016)
Fatima 2014 2015 Pakistan Camelus dromedarius 3 1 c-ELISA I Blood Brucella spp ND Male Orchitis S S S ND ND S Serological, molecular detection, and potential risk factors associated with camel brucellosis in Pakistan. Tropical animal health and production (Fatima et al., 2016)
Fatima 2014 2015 Pakistan Camelus dromedarius 47 0 c-ELISA I Blood Brucella spp ND Male Healthy animal S S S ND ND S Serological, molecular detection, and potential risk factors associated with camel brucellosis in Pakistan. Tropical animal health, and production (Fatima et al., 2016)
Fatima 2014 2015 Pakistan Camelus dromedarius 47 0 rt-PCR I Blood Brucella spp ND Male Healthy animal S S S ND ND S Serological, molecular detection, and potential risk factors associated with camel brucellosis in Pakistan. Tropical animal health, and production(Fatima et al., 2016)
Fatima 2014 2015 Pakistan Camelus dromedarius 140 9 RBT I Blood Brucella spp ND Female Abortion S S S ND ND S Serological, molecular detection, and potential risk factors associated with camel brucellosis in Pakistan. Tropical animal health and production (Fatima et al., 2016)
Fatima 2014 2015 Pakistan Camelus dromedarius 140 3 c-ELISA I Blood Brucella spp ND Female Abortion S S S ND ND S Serological, molecular detection, and potential risk factors associated with camel brucellosis in Pakistan. Tropical animal health and production (Fatima et al., 2016)
Fatima 2014 2015 Pakistan Camelus dromedarius 140 3 rt-PCR I Blood Brucella spp ND Female Abortion S S S ND ND S Serological, molecular detection, and potential risk factors associated with camel brucellosis in Pakistan. Tropical animal health and production (Fatima et al., 2016)
Hosein 2014 2015 Egypt Camelus dromedarius 965 37 RBT I Blood Brucella spp ND Male Healthy animal ND ND ND ND ND ND Seroprevalence of camel brucellosis and molecular characterization of Brucella melitensis recovered from dromedary camels in Egypt (Hosein et al., 2016)
Hosein 2014 2015 Egypt Camelus dromedarius 170 10 RBT I Blood Brucella spp ND Female Healthy animal ND ND ND ND ND ND Seroprevalence of camel brucellosis and molecular characterization of Brucella melitensis recovered from dromedary camels in Egypt (Hosein et al., 2016)
Hosein 2014 2015 Egypt Camelus dromedarius 965 32 c-ELISA I Blood Brucella spp ND Male Healthy animal ND ND ND ND ND ND Seroprevalence of camel brucellosis and molecular characterization of Brucella melitensis recovered from dromedary camels in Egypt (Hosein et al., 2016)
Hosein 2014 2015 Egypt Camelus dromedarius 170 10 c-ELISA I Blood Brucella spp ND Female Healthy animal ND ND ND ND ND ND Seroprevalence of camel brucellosis and molecular characterization of Brucella melitensis recovered from dromedary camels in Egypt (Hosein et al., 2016)
Hosein 2014 2015 Egypt Camelus dromedarius 26 2 Culture D Milk Brucella melitensis 3 Female Healthy animal ND ND ND ND ND ND Seroprevalence of camel brucellosis and molecular characterization of Brucella melitensis recovered from dromedary camels in Egypt(Hosein et al., 2016)
Hosein 2014 2015 Egypt Camelus dromedarius 26 2 PCR D Milk Brucella melitensis 3 Female Healthy animal ND ND ND ND ND ND Seroprevalence of camel brucellosis and molecular characterization of Brucella melitensis recovered from dromedary camels in Egypt (Hosein et al., 2016)
Admasu 2014 2015 Ethiopia Camelus dromedarius 384 14 RBT I Blood Brucella spp ND ND Abortion S S NS ND ND NS Seroprevalence of camel brucellosis in Yabello District of Borena Zone, Southern Ethiopia (Admasu and Kaynata, 2017)
Admasu 2014 2015 Ethiopia Camelus dromedarius 91 4 CFT I Blood Brucella spp ND Male Abortion S S NS ND ND NS Seroprevalence of camel brucellosis in Yabello District of Borena Zone, Southern Ethiopia (Admasu and Kaynata, 2017)
Admasu 2014 2015 Ethiopia Camelus dromedarius 293 8 CFT I Blood Brucella spp ND Female Abortion S S NS ND ND NS Seroprevalence of camel brucellosis in Yabello District of Borena Zone, Southern Ethiopia(Admasu and Kaynata, 2017)
El-Sayed 2014 2015 Egypt Camelus dromedarius 801 103 RBT I Blood Brucella melitensis 3 Male Healthy animal ND ND ND ND ND ND Seroprevalence of camel brucellosis (Camelus dromedarius) and phenotypic characteristics of Brucella melitensis biovar 3 in Shalateen City, Red Sea Governorate, Egypt (El-Sayed et al., 2017)
El-Sayed 2014 2015 Egypt Camelus dromedarius 802 93 Buffered Acidified Plate Antigen Test I Blood Brucella melitensis 3 Male Healthy animal ND ND ND ND ND ND Seroprevalence of camel brucellosis (Camelus dromedarius) and phenotypic characteristics of Brucella melitensis biovar 3 in Shalateen City, Red Sea Governorate, Egypt (El-Sayed et al., 2017)
El-Sayed 2014 2015 Egypt Camelus dromedarius 803 92 CFT I Blood Brucella melitensis 3 Male Healthy animal ND ND ND ND ND ND Seroprevalence of camel brucellosis (Camelus dromedarius) and phenotypic characteristics of Brucella melitensis biovar 3 in Shalateen City, Red Sea Governorate, Egypt (El-Sayed et al., 2017)
Abdelgawad 2015 2016 Egypt Camelus dromedarius 112 16 RBT I Blood Brucella spp ND ND Healthy animal ND ND ND ND ND ND Serological and molecular detection of Brucella species in camels (Abdelgawad et al., 2017)
Abdelgawad 2015 2016 Egypt Camelus dromedarius 112 17 Buffered Acidified Plate Antigen Test I Blood Brucella spp ND ND Healthy animal ND ND ND ND ND ND Serological and molecular detection of Brucella species in camels (Abdelgawad et al., 2017)
Abdelgawad 2015 2016 Egypt Camelus dromedarius 112 18 CFT I Blood Brucella spp ND ND Healthy animal ND ND ND ND ND ND Serological and molecular detection of Brucella species in camels (Abdelgawad et al., 2017)
Abdelgawad 2015 2016 Egypt Camelus dromedarius 21 12 PCR D Lymph node Brucella melitensis ND ND Healthy animal ND ND ND ND ND ND Serological and molecular detection of Brucella species in camels (Abdelgawad et al., 2017)
Hanon 2016 2017 Iraq Camelus dromedarius 237 51 RBT I Blood Brucella spp ND ND Healthy animal ND S ND NS ND ND Seroprevalence of brucellosis and toxoplasmosis in camels of Wasit Province, Iraq (Hanon, 2017)
Hanon 2016 2017 Iraq Camelus dromedarius 28 1 CFT I Blood Brucella spp ND ND Healthy animal ND S ND NS ND ND Seroprevalence of brucellosis and toxoplasmosis in camels of Wasit Province, Iraq (Hanon, 2017)
Hanon 2016 2017 Iraq Camelus dromedarius 209 38 CFT I Blood Brucella spp ND ND Healthy animal ND S ND NS ND ND Seroprevalence of brucellosis and toxoplasmosis in camels of Wasit Province, Iraq(Hanon, 2017)
Hanon 2016 2017 Iraq Camelus dromedarius 237 7 PCR D Blood Brucella abortus ND Female Healthy animal ND ND ND ND ND ND Seroprevalence of brucellosis and toxoplasmosis in camels of Wasit Province, Iraq (Hanon, 2017)
Hanon 2016 2017 Iraq Camelus dromedarius 237 5 PCR D Blood Brucella melitensis ND Male Healthy animal ND ND ND ND ND ND Seroprevalence of brucellosis and toxoplasmosis in camels of Wasit Province, Iraq (Hanon, 2017)
Al-Busadah 2016 2017 Saudi Arabia Camelus dromedarius 94 2 PCR D Semen Brucella melitensis ND Male infertility ND ND ND ND ND ND Serum biochemical profile and molecular detection of pathogens in semen of infertile male dromedary camels (Camelus dromedarius) (Al-Busadah et al., 2017)
Shahzad 2016 2017 Pakistan Camelus dromedarius 761 26 RBT I Blood Brucella spp ND ND Abortion S S ND S S ND Seroprevalence and molecular investigation of brucellosis in camels of selected districts of Punjab, Pakistan (Shahzad et al., 2017)
Shahzad 2016 2017 Pakistan Camelus dromedarius 761 26 c-ELISA I Blood Brucella spp ND ND Abortion S S ND S S ND Seroprevalence and molecular investigation of brucellosis in camels of selected districts of Punjab, Pakistan (Shahzad et al., 2017)
Abdirahman 2017 2017 Kenya Camelus dromedarius 160 15 RBT I Blood Brucella spp ND ND Healthy animal ND ND ND ND ND ND Camel Brucellosis: Seroprevalence and pathological lesions at slaughterhouses in Garissa County, Kenya (Abdirahman, 2020)
Abdirahman 2017 2017 Kenya Camelus dromedarius 160 16 SAT I Blood Brucella spp ND ND Healthy animal ND ND ND ND ND ND Camel Brucellosis: Seroprevalence and pathological lesions at slaughterhouses in Garissa County, Kenya (Abdirahman, 2020)
Abdirahman 2017 2017 Kenya Camelus dromedarius 160 15 c-ELISA I Blood Brucella spp ND ND Healthy animal ND ND ND ND ND ND Camel Brucellosis: Sero-prevalence and pathological lesions at Slaughterhouses in Garissa County, Kenya (Abdirahman, 2020)
Alamian 2018 2018 Iran Camelus dromedarius 96 14 PCR D Milk Brucella abortus 3 Female Healthy animal ND ND ND ND ND ND Brucella abortus contamination of camel milk in two Iranian regions (Alamian and Dadar, 2019)
Khan 2018 2018 Iran Camelus dromedarius 96 3 Culture D Milk Brucella abortus 5 Female Healthy animal ND ND ND ND ND ND Brucella abortus contamination of camel milk in two Iranian regions (Alamian and Dadar, 2019)
Khan 2017 2019 Egypt Camelus dromedarius 295 52 RBT I Blood Brucella abortus ND Male Healthy animal NS NS ND ND ND ND Seroprevalence and molecular Identification of Brucella spp. in camels in Egypt (Khan et al., 2020)
Khan 2017 2019 Egypt Camelus dromedarius 86 7 RBT I Blood Brucella abortus ND Female Healthy animal NS NS ND ND ND ND Seroprevalence and molecular identification of Brucella spp. in camels in Egypt (Khan et al., 2020)
Khan 2017 2019 Egypt Camelus dromedarius 295 71 i-ELISA I Blood Brucella melitensis ND Male Healthy animal NS NS ND ND ND ND Seroprevalence and molecular identification of Brucella spp. in camels in Egypt (Khan et al., 2020)
Khan 2017 2019 Egypt Camelus dromedarius 86 16 i-ELISA I Blood Brucella abortus ND Female Healthy animal NS NS ND ND ND ND Seroprevalence and molecular identification of Brucella spp. in camels in Egypt (Khan et al., 2020)
Khan 2017 2019 Egypt Camelus dromedarius 295 66 c-ELISA I Blood Brucella abortus ND Male Healthy animal NS NS ND ND ND ND Seroprevalence and molecular identification of Brucella spp. in camels in Egypt(Khan et al., 2020)
Khan 2017 2019 Egypt Camelus dromedarius 86 11 c-ELISA I Blood Brucella abortus ND Female Healthy animal NS NS ND ND ND ND Seroprevalence and molecular identification of Brucella spp. in camels in Egypt(Khan et al., 2020)
Khan 2017 2019 Egypt Camelus dromedarius 295 66 CFT I Blood Brucella spp ND Male Healthy animal NS NS ND ND ND ND Seroprevalence and molecular identification of Brucella spp. in camels in Egypt(Khan et al., 2020)
Khan 2017 2019 Egypt Camelus dromedarius 86 11 CFT I Blood Brucella spp ND Female Healthy animal NS NS ND ND ND ND Seroprevalence and molecular identification of Brucella spp. in camels in Egypt(Khan et al., 2020)
Khan 2017 2019 Egypt Camelus dromedarius 295 101 rt-PCR I Blood Brucella suis ND Male Healthy animal NS NS ND ND ND ND Seroprevalence and molecular identification of Brucella spp. in camels in Egypt(Khan et al., 2020)
Khan 2017 2019 Egypt Camelus dromedarius 86 15 rt-PCR I Blood Brucella abortus ND Female Healthy animal NS NS ND ND ND ND Seroprevalence and molecular identification of Brucella spp. in camels in Egypt(Khan et al., 2020)
Alatabi 2018 2019 Iraq Camelus dromedarius 172 6 RBT I Blood Brucella spp ND ND Healthy animal ND ND ND S ND S Serodiagnosis for brucellosis in camels by rose Bengal and C-ELISA test in Iraq (Alatabi et al., 2020)
Alatabi 2018 2019 Iraq Camelus dromedarius 172 4 c-ELISA I Blood Brucella spp ND ND Healthy animal ND ND ND S ND S Serodiagnosis for brucellosis in camels by rose Bengal and C-ELISA test in Iraq (Alatabi et al., 2020)
Alrawahi 2019 2019 Oman Camelus dromedarius 2250 9 RBT I Blood Brucella spp ND ND Healthy animal S S S S NS NS A cross-sectional seroepidemiological study of camel (Camelus dromedarius) brucellosis and associated risk factors in the Sultanate of Oman (Alrawahi et al., 2019)
Alrawahi 2019 2019 Oman Camelus dromedarius 252 0 CFT I Blood Brucella spp ND ND Healthy animal S S S S NS NS A cross-sectional seroepidemiological study of camel (Camelus dromedarius) brucellosis and associated risk factors in the Sultanate of Oman (Alrawahi et al., 2019)
Alrawahi 2019 2019 Oman Camelus dromedarius 1998 9 CFT I Blood Brucella spp ND ND Healthy animal S S S S NS NS A cross-sectional seroepidemiological study of camel (Camelus dromedarius) brucellosis and associated risk factors in the Sultanate of Oman (Alrawahi et al., 2019)
Wegi 2019 2020 Ethiopia Camelus dromedarius 250 19 RBT I Blood Brucella spp ND ND Abortion ND ND ND S S ND Brucellosis in cattle, camel, and human: seroprevalence and associated risk factors in amibara district of afar region, Ethiopia (Gutema Wegi, 2020)
Wegi 2019 2020 Ethiopia Camelus dromedarius 250 8 CFT I Blood Brucella spp ND ND Abortion ND ND ND S S ND Brucellosis in cattle, camel, and human: seroprevalence and associated risk factors in amibara district of afar region, Ethiopia (Gutema Wegi, 2020)
Rabah 2019 2020 Egypt Camelus dromedarius 100 10 RBT I Blood Brucella spp ND ND Healthy animal S S ND S ND ND Serological and molecular epidemiological study on Brucellosis in camels and humans in Matrouh Province (Rabah et al., 2020)
Rabah 2019 2020 Egypt Camelus dromedarius 100 10 Buffered Acidified Plate Antigen Test I Blood Brucella spp ND ND Healthy animal S S ND S ND ND Serological and molecular epidemiological study on Brucellosis in camels and humans in Matrouh Province(Rabah et al., 2020)
Rabah 2019 2020 Egypt Camelus dromedarius 100 9 CFT I Blood Brucella spp ND ND Healthy animal S S ND S ND ND Serological and molecular epidemiological study on Brucellosis in camels and human in Matrouh Province(Rabah et al., 2020)
Rabah 2019 2020 Egypt Camelus dromedarius 100 9 PCR I Blood Brucella abortus ND ND Healthy animal S S ND S ND ND Serological and molecular epidemiological study on Brucellosis in camels and humans in Matrouh Province(Rabah et al., 2020)
Ibrahim 2020 2020 Egypt Camelus dromedarius 272 11 RBT I Blood Brucella spp ND ND Healthy animal S NS ND ND ND ND Serological, molecular detection, and potential risk factors associated with camel brucellosis in Pakistan. Tropical animal health and production (Ibrahim et al., 2020)
Ibrahim 2020 2020 Egypt Camelus dromedarius 272 10 c-ELISA I Blood Brucella spp ND ND Healthy animal S NS ND ND ND ND Serological, molecular detection, and potential risk factors associated with camel brucellosis in Pakistan. Tropical animal health and production (Ibrahim et al., 2020)
Ibrahim 2020 2020 Egypt Camelus dromedarius 115 21 c-ELISA I Blood Brucella spp ND Female Abortion S NS ND ND ND ND Serological, molecular detection, and potential risk factors associated with camel brucellosis in Pakistan. Tropical animal health and production (Ibrahim et al., 2020)
Ibrahim 2020 2020 Ethiopia Camelus dromedarius 141 1 i-ELISA I Blood Brucella spp ND ND Healthy animal ND ND ND ND ND ND Sero-prevalence of brucellosis, Q-fever and Rift Valley Fever in humans and livestock in the Somali region, Ethiopia (Ibrahim et al., 2020)
Dadar 2020 2020 Iran Camelus dromedaries 2854 10 RBT I Blood Brucella spp ND Male Healthy animal ND ND ND ND ND ND Isolation of Brucella melitensis from seronegative camel: potential implications in brucellosis control(Dadar and Alamian, 2020)
Dadar 2020 2020 Iran Camelus dromedarius 2854 7 SAT I Blood Brucella spp ND Male Healthy animal ND ND ND ND ND ND Isolation of Brucella melitensis from seronegative camel: potential implications in brucellosis control(Dadar and Alamian, 2020)
Dadar 2020 2020 Iran Camelus dromedarius 2854 6 2-ME I Blood Brucella spp ND Male Healthy animal ND ND ND ND ND ND Isolation of Brucella melitensis from seronegative camel: potential implications in brucellosis control (Dadar and Alamian, 2020)
Dadar 2020 2020 Iran Camelus dromedarius 40 9 PCR D Lymph node Brucella melitensis ND Male Healthy animal ND ND ND ND ND ND Isolation of Brucella melitensis from seronegative camel: potential implications in brucellosis control (Dadar and Alamian, 2020)
Khalafalla 2020 2020 United Arab Emirates Camelus dromedarius 68 36 RBT I Blood Brucella spp ND ND Healthy animal ND ND ND ND ND ND Preliminary Comparative Assessment of Brucellergene Skin Test for Diagnosis of Brucellosis in Dromedary Camels (Camelus dromedarius)(Khalafalla et al., 2020)
Khalafalla 2020 2020 United Arab Emirates Camelus dromedarius 68 36 c-ELISA I Blood Brucella spp ND ND Healthy animal ND ND ND ND ND ND Preliminary Comparative Assessment of Brucellergene Skin Test for Diagnosis of Brucellosis in Dromedary Camels (Camelus dromedarius) (Khalafalla et al., 2020)
Khalafalla 2020 2020 United Arab Emirates Camelus dromedarius 68 29 Brucellergene skin test I Blood Brucella spp ND ND Healthy animal ND ND ND ND ND ND Preliminary Comparative Assessment of Brucellergene Skin Test for Diagnosis of Brucellosis in Dromedary Camels (Camelus dromedarius) (Khalafalla et al., 2020)
Noor 2020 2020 Kenya Camelus dromedarius 104 4 MRT I Milk Brucella spp ND Female Healthy animal S S S S ND S Prevalence, Risk Factors Associated with Brucellosis and Presence of Pathogenic Bacteria Isolated from Camel Milk in Garissa County, Kenya(Noor et al., 2020)
Shehzad 2020 2020 Pakistan Camelus dromedarius 214 7 RBT I Blood Brucella spp ND ND Healthy animal ND ND ND ND ND ND Seroprevalence and potential risk factors associated with brucellosis in the Desert Thal of Pakistan (Shehzad et al., 2020)
Shehzad 2020 2020 Pakistan Camelus dromedarius 214 0 c-ELISA I Blood Brucella spp ND ND Healthy animal ND ND ND ND ND ND Seroprevalence and potential risk factors associated with brucellosis in the Desert Thal of Pakistan (Shehzad et al., 2020)