A review on camel brucellosis: a zoonosis sustained by ignorance and indifference

The burden of brucellosis in donkeys and its implications for public health and animal welfare: A systematic review and meta-analysis

Background and Aim

Brucellosis is a globally significant zoonotic disease affecting a wide range of wild and domestic animals, with implications for human and animal health. Despite donkeys' crucial roles in agriculture, transportation, and livelihoods, there is limited research on the burden of brucellosis in this species. This study systematically reviews the prevalence and role of donkeys as reservoirs for Brucella spp., providing insights into their public health implications.

Materials and Methods

Using the PRISMA guidelines, a systematic search of PubMed, Scopus, and Google Scholar was conducted for studies published from 1990 to May 2024. Out of 1159 retrieved articles, 20 met the inclusion criteria. Data on study design, location, diagnostic methods, and brucellosis prevalence were extracted and analyzed using R statistical software. Pooled prevalence and heterogeneity were calculated, and the Newcastle-Ottawa Scale was employed to assess study quality.

Results

The pooled prevalence of brucellosis in 6785 donkeys across 20 studies was 10.23% (range: 0%-63.7%), with the highest prevalence reported in Asia (26.80%). While 15% of studies suggested that donkeys act as reservoirs for Brucella spp., direct evidence linking donkeys to disease transmission remains scarce. The disease's impact on donkey reproduction, including abortion and infertility, is underexplored, highlighting a significant research gap.

Conclusion

Brucellosis in donkeys represents a notable zoonotic and occupational risk. The limited data from East Africa, despite its high donkey population, emphasize the need for comprehensive epidemiological studies. Findings underscore the importance of targeted interventions, including biosecurity, public education, and enhanced diagnostic approaches, to mitigate brucellosis' impact on donkey health and its broader public health implications.

Camel milk is a neglected source of brucellosis among rural Arab communities

The World Health Organization describes brucellosis as one of the world's leading zoonotic diseases, with the Middle East a global hotspot. Brucella melitensis is endemic among livestock populations in the region, with zoonotic transmission occurring via consumption of raw milk, amongst other routes. Control is largely via vaccination of small ruminant and cattle populations. Due to sociocultural and religious influences camel milk (camelus dromedarius) is widely consumed raw, while milk from other livestock species is largely boiled. To investigate the potential public health impact of Brucella in camels we conduct a cross-sectional study in southern Jordan including 227 herds and 202 livestock-owning households. Here we show daily consumption of raw camel milk is associated with Brucella seropositive status among the study population, ORadj 2.19 (95%CI 1.23-3.94) on multivariable analysis, highlighting the need for socioculturally appropriate control measures; targeted interventions among the camel reservoir being crucial for effective control.

Camel Brucellosis: Seroprevalence, Associated Risk Factor, and Public Health Perceptions in Arero District of Borena Zone, Southern Ethiopia

A cross-sectional study was conducted to determine the seroprevalence and potential risk factors of camel brucellosis and to assess public health awareness of the disease in the selected kebele of Arero District, Borena Zone, Southern Ethiopia. A total of 313 blood samples were collected from selected camels using a systematic random sampling technique. The serum samples underwent initial screening for brucellosis using the rose Bengal plate test (RBPT), with further confirmation through the indirect enzyme-linked immunosorbent Assay (i-ELISA). The overall seroprevalence of camel brucellosis was 7.66% using RBPT and 2.24% using i-ELISA. Univariable and multivariable logistic regression analyses revealed significant associations; female camels (OR = 30.16, p=0.05) and mixing camels with other animal species (OR = 0.019, p=0.001 by i-ELISA) were significantly linked to camel seropositivity for Brucella infection. Assessment of public health perception and awareness from 227 owners indicated limited awareness; most respondents lacked knowledge about brucellosis (94.27%), 82.82% were unaware of raw meat risks, 94.27% did not know about brucellosis being zoonotic, and 18.94% consumed raw milk with blood. The majority (94.71%) practiced bare-handed calving, with 93.39% handling abortion materials, rarely isolating infected camels. The study found a moderate prevalence of brucellosis among camels in the study areas. Lack of implemented control strategies, combined with local pastoral practices, could potentially contribute to disease spread. Therefore, there should be continuous efforts of the disease control strategy at the animal level, community awareness creation, separation of infected camels from health heard, and avoiding mixing a camel with other animal species.

Poor semen quality is associated with impaired antioxidant response and acute phase proteins and is likely mediated by high cortisol levels in Brucella-seropositive dromedary camel bulls

Brucellosis in dromedary camel bulls leads to either temporary or permanent loss of fertility. Camel brucellosis is associated with both orchitis and epididymitis. However, the clinical signs of camel brucellosis are not clear as those in cattle. Therefore, this study aimed to diagnose camel brucellosis based on a serological screening using Rose Bengal plate test (RBPT) followed by competitive ELISA. To understand the impact of brucellosis on camel bull fertility, this study aimed to examine the semen characteristics, evaluate the testicular histopathology, examine hormonal profile, antioxidants and acute phase proteins (APP). A total of 150 mature bulls were used in this study. Blood samples were collected for serological, hormonal, and biochemical analysis. This study revealed that 6.6% and 7.3% of the examined bulls were Brucella-seropositive using RBPT and competitive ELISA, respectively. The Brucella-seropositive dromedary bulls showed poor semen quality, pathological changes orchitis, and lower testosterone. Moreover, our findings showed a higher cortisol level, and significant impairments in the measured APP and antioxidants in Brucella-seropositive bulls. In conclusion, the Brucella-seropositive dromedary bulls showed lower fertility due to poor semen quality and lower testosterone levels. Such lower fertility is likely mediated by high cortisol levels, and impaired APP and antioxidants' defense response.

Brucellosis: Unveiling the complexities of a pervasive zoonotic disease and its global impacts

One zoonotic infectious animal disease is brucellosis. The bacteria that cause brucellosis belong to the genus Brucella. Numerous animal and human species are affected by brucellosis, with an estimated 500,000 human cases recorded annually worldwide. The occurrence of new areas of infection and the resurgence of infection in already infected areas indicate how dynamically brucellosis is distributed throughout different geographic regions. Bacteria originate from the blood and are found in the reticuloendothelial system, the liver, the spleen, and numerous other locations, including the joints, kidneys, heart, and genital tract. Diagnosis of this disease can be done by bacterial isolation, molecular tests, modified acid-fast stain, rose bengal test (RBT), milk ring test, complement fixation test, enzyme-linked immunosorbent assay, and serum agglutination test. The primary sign of a Brucella abortus infection is infertility, which can result in abortion and the birth of a frail fetus that may go on to infect other animals. In humans, the main symptoms are acute febrile illness, with or without localization signs, and chronic infection. Female cattle have a greater risk of contracting Brucella disease. Human populations at high risk of contracting brucellosis include those who care for cattle, veterinarians, slaughterhouse employees, and butchers. Antibiotic treatment of brucellosis is often unsuccessful due to the intracellular survival of Brucella and its adaptability in macrophages. A "one health" strategy is necessary to control illnesses like brucellosis.

Exposure to Brucella Species, Coxiella burnetii, and Trichinella Species in Recently Imported Camels from Sudan to Egypt: Possible Threats to Animal and Human Health

Brucellosis and coxiellosis/Q fever are bacterial infections caused by Brucella species and Coxiella burnetii, respectively; camels are highly susceptible to both pathogens. Trichinellosis is a parasitic infection caused by various Trichinella nematode species. Reportedly, camels are susceptible to experimental infection with Trichinella spp., but information on this potential host species is scarce. All three infections are of zoonotic nature and thus of great public health concern. The current study aimed to determine antibodies against the three pathogens in recently imported camels (n = 491) from Sudan at the two main ports for the entrance of camels into southern Egypt using commercial indirect ELISAs. Samples were collected in two sampling periods. The seropositivity rates of Brucella spp., C. burnetii, and Trichinella spp. were 3.5%, 4.3%, and 2.4%, respectively. Mixed seropositivity was found in 1% for Brucella spp. and C. burnetii. Marked differences were found between the two study sites and the two sampling periods for Brucella. A higher rate of seropositivity was recorded in the Red Sea/older samples that were collected between 2015 and 2016 (4.3%, 17/391; odds ratio = 9.4; p < 0.030) than in those collected in Aswan/recent samples that were collected between 2018 and 2021 (0/100). Concerning C. burnetii, samples collected during November and December 2015 had a significantly higher positivity rate than the other samples (13%, 13/100; OD = 4.8; p < 0.016). The same effect was observed for antibodies to Trichinella spp., with samples collected during November and December 2015 showing a higher positivity rate than the other samples (7%, 7/100; OD = 10.9; p < 0.001). This study provides valuable information on the seroprevalence of Brucella spp. and additional novel information on C. burnetii and Trichinella spp. in recently imported camels kept in quarantine before delivery to other Egyptian regions. This knowledge can be utilized to reduce health hazards and financial burdens attributable to brucellosis, Q fever, and trichinellosis in animals and humans in Egypt.

Serological and molecular survey of brucellosis and chlamydiosis in dromedary camels from Tunisia

The present sero-epidemiological survey was designed and conducted to scrutinize the current status of camel-related brucellosis and chlamydiosis in Tunisia. Whole blood and serum samples were collected from 470 dromedaries (Camelus dromedarius) from eight different Tunisian governorates. Serum samples were subjected to indirect enzyme-linked immunosorbent assay (iELISA). The detection of Brucella and Chlamydia DNA was performed using conventional PCR targeting the bcsp-31 and 16 S rRNA gene, respectively. Overall, 10/470(2.12%) and 27/470 (5.75%) camels were revealed seropositive to Brucella and Chlamydia, respectively. Multivariate logistic regression analysis showed different risk factors associated with these infections. Meaningful high rates of seropositivity of brucellosis (9.5%; p = 0.000; OR=64.193) and chlamydiosis (22.6%; p = 0.000; OR=42.860) were noted among camels showing previous abortions in particular for aged females. Besides, Chlamydia seropositivity is significantly important during winter (12.5%; p = 0.009; OR= 27.533), and in camels raised in small farms (11.4%, p = 0.000, OR=86.052). Molecular analysis revealed no positivity from all analyzed blood samples. These findings indicate the involvement of camels in the epidemiology of these abortive infectious diseases. This raises awareness and serious public health concern for infectious camel diseases in order to develop further diagnostic improvements and effective control strategies.

Seroprevalence and risk factors of brucellosis in dromedary camels (Camelus dromedarius) in Sudan from 1980 to 2020: a systematic review and meta-analysis

Camel brucellosis is a major public health concern in Sudan; however, there is no overall estimation of the prevalence of camel brucellosis in Sudan. Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, this study aimed to perform a meta-analysis of 30 eligible studies published before December 31, 2022, with a total of 70059 dromedary camels, to estimate the pooled prevalence of camel brucellosis and its risk factors in Sudan. The random effect model was used for the final analysis due to the significantly high heterogeneity among the included studies, and the results showed that the overall pooled prevalence of camel brucellosis was 17%, with a confidence interval (CI) of 12%-21%. The prevalence was higher in males than females (54% vs. 46%) and in adults than youngling (77% vs. 23%). The prevalence also varied by region, with central and northern Sudan having the highest prevalence (24%), compared to other regions of Sudan. Moreover, the prevalence of camel brucellosis appeared to be decreasing over time. The current study concluded that camel brucellosis infection is still endemic in many areas of Sudan, with the disease being especially prevalent in central and northern Sudan. Thus, this study provides valuable information for the prevention and control of camel brucellosis in Sudan. However, the significant heterogeneity among the included studies should be taken into account when interpreting these results. Finally, to provide adequate information, research must be updated, and more research must be conducted in many regions of Sudan.

Associations between unpasteurised camel and other milk consumption, livestock ownership, and self-reported febrile and gastrointestinal symptoms among semi-pastoralists and pastoralists in the Somali Region of Ethiopia

Contact with livestock and consumption of unpasteurised dairy products are associated with an increased risk of zoonotic and foodborne infection, particularly among populations with close animal contact, including pastoralists and semi-pastoralists. However, there are limited data on disease risk factors among pastoralists and other populations where livestock herding, particularly of dromedary camels, is common. This cross-sectional study used a previously validated survey instrument to identify risk factors for self-reported symptoms. Adults (n = 304) were randomly selected from households (n = 171) in the Somali Region of Ethiopia, a region characterised by chronic food insecurity, population displacement, recurrent droughts and large semi-pastoralist and pastoralist populations. Multivariable logistic regression assessed associations between self-reported symptoms and type of milk consumed, controlling for demographics and human-animal interaction. Consumption of days-old unrefrigerated raw camel milk was significantly associated with symptoms in the 30 days prior to the survey (AOR = 5.07; 95% CI 2.41-10.66), after controlling for age, refugee status, sanitation, camel ownership and source of drinking water and accounting for clustering. Consumption of days-old unrefrigerated raw ruminant milk was significantly associated with symptoms (AOR = 4.00, 95% CI 1.27-12.58). Source of drinking water and camel ownership, a proxy for camel contact, were significantly associated with the outcome in each model. There were no significant associations between self-reported symptoms and fresh or soured animal milk consumption. Research is needed to identify pathogens and major routes of transmission. Tailored communication campaigns to encourage safe food preparation should also be considered.

Importance of brucellosis control programs of livestock on the improvement of one health

Brucellosis not only represents an important health restraint on livestock but also causes high economic losses in many developing countries worldwide. Despite considerable efforts made for the control of brucellosis, the disease is still spreading in many regions (such as the Middle East) where it represents one of the most important health hazards impacting both animals and humans. The present review aims to investigate the efficacy of veterinary control programs regarding brucellosis, with a special focus on current prevention, control, and eradication approaches. The reasons for unsuccessful control programs such as the absence of highly effective vaccines and non-certified bulls are also debated, to understand why the prevalence of brucellosis in livestock is not decreasing in many areas despite considerable efforts taken to date. The importance of governmental and regional investment in brucellosis control remains one of the main limiting factors owing to the limited budget allocated to tackle this disease. In this context, one health concept has generated novel comprehensive approaches with multiple economic implications across the livestock industry and public health. However, the implementation of such global preventive strategies appears to be a key issue for many endemic and low-income countries. According to the collected data, epidemiological contexts including management and trade systems along with well-defined agro-ecological zones should be evaluated in brucellosis endemic countries to improve milk production and to enhance the sustainability of the livestock sector at both national and regional levels.

Bovine brucellosis - a comprehensive review

Brucellosis is a zoonotic disease of great animal welfare and economic implications worldwide known since ancient times. The emergence of brucellosis in new areas as well as transmission of brucellosis from wild and domestic animals is of great significance in terms of new epidemiological dimensions. Brucellosis poses a major public health threat by the consumption of non-pasteurized milk and milk products produced by unhygienic dairy farms in endemic areas. Regular and meticulous surveillance is essentially required to determine the true picture of brucellosis especially in areas with continuous high prevalence. Additionally, international migration of humans, animals and trade of animal products has created a challenge for disease spread and diagnosis in non-endemic areas. Isolation and identification remain the gold standard test, which requires expertise. The advancement in diagnostic strategies coupled with screening of newly introduced animals is warranted to control the disease. Of note, the diagnostic value of miRNAs for appropriate detection of B. abortus infection has been shown. The most widely used vaccine strains to protect against Brucella infection and related abortions in cattle are strain 19 and RB51. Moreover, it is very important to note that no vaccine, which is highly protective, safe and effective is available either for bovines or human beings. Research results encourage the use of bacteriophage lysates in treatment of bovine brucellosis. One Health approach can aid in control of this disease, both in animals and man.

Brucella Shunt Infection Complicated by Peritonitis: Case Report and Review of the Literature

Brucellosis is an endemic zoonotic disease in the Mediterranean basin and Middle East. The disease remains a diagnostic challenge due to an increasing trend of ambiguous and non-specific manifestations. We report a rare case of a 9-year-old boy who had a left frontotemporal arachnoid cyst with cystoperitoneal shunt who presented with fever for 2 weeks with gastrointestinal symptoms. He had no neurological manifestations. Diagnosis of Brucella shunt infection complicated with a peritoneal collection was established by isolation of the organism from cerebrospinal fluid (CSF) culture. Successful treatment was accomplished by shunt replacement and intravenous antibiotics followed by step-down oral therapy for an 18-month duration based on serological and radiological responses with no sequelae. We also reviewed the reported cases of CSF shunt infection in the literature for further guidance. Brucella shunt infection may be difficult to diagnose due to the diversity of signs and symptoms and the low yield on culture. Brucellosis should be always kept in mind in the differential diagnosis of patients living in endemic area with fever and non-specific symptoms. Diagnosis depends on a high index of suspicion. In addition to drug therapy, device replacement is advised to prevent treatment failure.

Serological evidence of single and mixed infections of Rift Valley fever virus, Brucella spp. and Coxiella burnetii in dromedary camels in Kenya

Camels are increasingly becoming the livestock of choice for pastoralists reeling from effects of climate change in semi-arid and arid parts of Kenya. As the population of camels rises, better understanding of their role in the epidemiology of zoonotic diseases in Kenya is a public health priority. Rift Valley fever (RVF), brucellosis and Q fever are three of the top priority diseases in the country but the involvement of camels in the transmission dynamics of these diseases is poorly understood. We analyzed 120 camel serum samples from northern Kenya to establish seropositivity rates of the three pathogens and to characterize the infecting Brucella species using molecular assays. We found seropositivity of 24.2% (95% confidence interval [CI]: 16.5–31.8%) for Brucella, 20.8% (95% CI: 13.6–28.1%) and 14.2% (95% CI: 7.9–20.4%) for Coxiella burnetii and Rift valley fever virus respectively. We found 27.5% (95% CI: 19.5–35.5%) of the animals were seropositive for at least one pathogen and 13.3% (95% CI: 7.2–19.4%) were seropositive for at least two pathogens. B. melitensis was the only Brucella spp. detected. The high sero-positivity rates are indicative of the endemicity of these pathogens among camel populations and the possible role the species has in the epidemiology of zoonotic diseases. Considering the strong association between human infection and contact with livestock for most zoonotic infections in Kenya, there is immediate need to conduct further research to determine the role of camels in transmission of these zoonoses to other livestock species and humans. This information will be useful for designing more effective surveillance systems and intervention measures.

Dromedary camels are well adapted to the arid and semi-arid environment that makes up about 80% of Kenya’s landmass. As such, camels play an important role in the socio-economic wellbeing and food security of pastoralists in the country. However, the species remains relatively neglected in scientific research, one of the main reasons being camels are mostly found in remote, low-income, arid regions of Africa and Asia. We carried out a study to determine the levels of exposure of camels in northern Kenya to Brucella spp., Coxiella burnetii and Rift Valley fever virus, three priority zoonotic pathogens in the country. We found high levels of exposure to the three pathogens, indicating the important role camels might play in the epidemiology of the zoonotic diseases in humans and other livestock. Based on the study findings, we argue for the immediate need for investments in disease surveillance and control strategies for priority zoonotic disease in camels in Kenya.

Coxiella burnetii in Dromedary Camels (Camelus dromedarius): A Possible Threat for Humans and Livestock in North Africa and the Near and Middle East?

The "One Health" concept recognizes that human health is connected to animal health and to the ecosystems. Coxiella burnetii-induced human Q fever is one of the most widespread neglected zoonosis. The main animal reservoirs responsible for C. burnetii transmission to humans are domesticated ruminants, primarily goats, sheep, and cattle. Although studies are still too sparse to draw definitive conclusions, the most recent C. burnetii serosurvey studies conducted in herds and farms in Africa, North Africa, Arabian Peninsula, and Asia highlighted that seroprevalence was strikingly higher in dromedary camels (Camelus dromedarius) than in other ruminants. The C. burnetii seroprevalence in camel herds can reach more than 60% in Egypt, Saudi Arabia, and Sudan, and 70 to 80% in Algeria and Chad, respectively. The highest seroprevalence was in female camels with a previous history of abortion. Moreover, C. burnetii infection was reported in ticks of the Hyalomma dromedarii and Hyalomma impeltatum species collected on camels. Even if dromedary camels represent <3% of the domesticated ruminants in the countries of the Mediterranean basin Southern coast, these animals play a major socioeconomic role for millions of people who live in the arid zones of Africa, Middle East, and Asia. In Chad and Somalia, camels account for about 7 and 21% of domesticated ruminants, respectively. To meet the growing consumers demand of camel meat and milk (>5 million tons/year of both raw and pasteurized milk according to the Food and Agriculture Organization) sustained by a rapid increase of population (growth rate: 2.26-3.76 per year in North Africa), dromedary camel breeding tends to increase from the Maghreb to the Arabic countries. Because of possible long-term persistence of C. burnetii in camel hump adipocytes, this pathogen could represent a threat for herds and breeding farms and ultimately for public health. Because this review highlights a hyperendemia of C. burnetii in dromedary camels, a proper screening of herds and breeding farms for C. burnetii is urgently needed in countries where camel breeding is on the rise. Moreover, the risk of C. burnetii transmission from camel to human should be further evaluated.

Isolation of Brucella melitensis from seronegative camel: potential implications in brucellosis control

Brucellosis is a significant zoonotic infection in Iran impacting both humans and animal health status. A number of reasons such as few clinical signs complicate the diagnosis of this infection in Camelidae. Despite the ubiquitous use of serological tests for the first screening of brucellosis in camel, this approach showed several restrictions because of the intracellular properties of this organism as well as decline antibody titers in chronic stage. This study aimed at identifying the presence of Brucella spp. in blood and lymph node samples collected from slaughtered male camels of Sistan-Baluchistan province by serology, culture and polymerase chain reaction (PCR) assay. For this purpose, 2854 blood camel samples were sampled and analyzed for Brucella detection by serological screening tests. The molecular detection of IS711 gene and Bruce-ladder assay as well as culture were performed using the lymph nodes of all seropositive camel (n = 10) and 30 seronegative samples. Results showed that 0.35% (10/2854), 0.24% (7/2854) and 0.21% (6/2854) of blood samples were positive by RBPT, SAT and 2ME, respectively. However, 0% (0/10) and 70% (7/10) of lymph node samples collected from seropositive camels were positive for Brucella infection by culture and PCR, respectively. Furthermore, 6.6% (2/30) of seronegative lymph node specimens showed the presences of Brucella by PCR and culture assay. The results of the present study indicated the low seroprevalence of Brucella infection in male camels of the Sistan-Baluchistan province and highlighted the complementary role of PCR techniques for a better screening of Brucella infection among seronegative camels. Moreover, the potential shedding of Brucella within undiagnosed camel milk and secretions is a serious problem which may result in further spread and maintenance of Brucella infection among both human and livestock. Thus, for brucellosis detection and control, our results suggested that a first PCR screening supported by a bacteriological isolation on positive samples should be performed along with the serological test in endemic countries to identify the source and prevent the uncontrolled spread of the disease among camels.

Serological study on brucellosis in captive elephants (Elephas maximus) and stray dogs in North Thailand

Background and Aim:

Brucellosis is considered as an important zoonotic disease caused by various strains of Brucella in numerous host species. Although brucellosis has been reported in almost animal species, the relevance of brucellosis infection and diagnostic technique in Asian elephant (Elephas maximus) has been limited. The present serological investigation aimed to investigate the antibody response to Brucella abortus in captive Asian elephants in North Thailand. Moreover, further serological survey was also conducted to detect the antibody response to Brucella canis in stray dogs cohabiting the same area as the elephant herd.

Materials and Methods:

Serum samples were collected from 40 captive Asian elephants and submitted for serological analysis based on B. abortus antigen using Rose Bengal plate test (RBPT) in combination with ethylenediaminetetraacetic acid-tube agglutination test (EDTA-TAT) as a supplementary test and by commercial indirect enzyme-linked immunosorbent assay (iELISA). In addition, serum samples were also obtained from 16 stray dogs that live nearby the elephant-raising area and were tested using commercial Dot-ELISA based on B. canis antigen.

Results:

Serological analysis in captive Asian elephants showed 100% seronegative (40/40) from all serological tests response to B. abortus. For stray dogs, 12.5% (2/16) had a low positive reaction response to B. canis.

Conclusion:

The serological survey for brucellosis in Asian elephant was adapted and applied using RBPT, EDTA-TAT, and iELISA in the present study. For future evaluation, we recommended the use of a combination of serological tests with validation together with comparing by direct detection such as bacterial isolation to provide an appropriate brucellosis surveillance program in Asian elephants. In addition, the surveillance of stray dogs or multispecies habitation should be kept into considerations.

Zoonotic Pathogens of Dromedary Camels in Kenya: A Systematised Review

Kenya is home to Africa’s third largest population of dromedary camels, and production at commercial and local levels are increasingly important. In pastoral and nomadic communities in the arid and semi-arid lands (ASALs), camels play a vital role in food security, while commercial milk production and formalized export markets are rapidly emerging as camel populations expand into non-traditional areas. Until recently, little focus was placed on camels as hosts of zoonotic disease, but the emergence of Middle Eastern respiratory coronavirus (MERS-CoV) in 2012, and the discovery of exposure to the virus in Kenyan camels, highlighted the need for further understanding of this area. This systematised review utilised a robust search strategy to assess the occurrence of camel-associated zoonoses in Kenya and to evaluate the quality of the published literature. Seventy-four studies were identified, covering sixteen pathogens, with an increasing number of good quality studies in recent years. Despite this, the area remains under-researched and there is a lack of robust, high-quality research. Trypanosome spp., Echinococcus granulosus and Brucella spp. appeared most frequently in the literature. Pathogens with the highest reported prevalence were MERS-CoV (0–100%), Echinococcus granulosa (7–60%) and Rift Valley fever virus (7–57%). Exposure to Brucella spp., Coxiella burnetii and Crimean-Congo haemorrhagic fever virus showed higher levels in camel or camel-associated vectors than other livestock species, although brucellosis was the only disease for which there was robust evidence linking camel and human exposure. Zoonotic agents with less severe human health outcomes, such as Dermatophilosus congolensis and contagious ecthyma, were also represented in the literature. This review provides an important summary of the scope and quality of current knowledge. It demonstrates that further research, and improved adherence to robust study design and reporting are essential if the zoonotic risk from camels in Kenya, and elsewhere, is to be better understood.

Seroprevalence and Molecular Identification of Brucella spp. in Camels in Egypt

Brucellosis is one of the most important worldwide zoonoses of many countries including Egypt. Camel brucellosis has not gained much attention in Egypt yet. This study is focused on the three governorates with the highest camel populations and the largest camel markets in the country to determine the disease seroprevalence and identify the Brucella species in local camel holdings. In total, 381 serum samples were collected from male and female camels from Giza, Aswan, and Al-Bahr Al-Ahmar (the Red Sea) governorates. Samples were serologically examined using the Rose-Bengal plate test (RBPT), indirect ELISA (i-ELISA), competitive ELISA (c-ELISA) and complement fixation test (CFT). Brucella antibodies were detected in 59 (15.5%), 87 (22.8%), 77 (20.2%) and 118 (31.0%) of sera by RBPT, i-ELISA, c-ELISA and CFT, respectively. Using real-time PCR, Brucella DNA was amplified in 32 (8.4%) seropositive samples including Brucella abortus (25/32), Brucella suis (5/32) and Brucella melitensis (2/32), defining a complex epidemiological status. To the best of our knowledge, this is the first study reporting Brucella suis DNA in camel serum. The risk-associated factors including age, sex, breed and geographical distribution were statistically analyzed, showing non-significant association with seroprevalence. The results of this study will raise awareness for camel brucellosis and help develop effective control strategies.

Brucellosis in the Middle East: Current situation and a pathway forward

Brucellosis is a bacterial endemic zoonotic disease of global significance with detrimental impacts on public health and food animal production. It is caused by Brucella spp., an expanding group of pathogens able to infect various host species. Bovines and small ruminants, which excrete the bacteria in milk and in reproductive discharges, are major sources of infection for humans and other animals. Contact with contaminated animals and consumption of unpasteurized dairy products are the main routes for human infection. In spite of the considerable progress of knowledge gained and success achieved in brucellosis control in the developed world, this disease continues to be an important burden in the Middle East (ME). Common risk factors implicated in the difficulty and complexity of brucellosis control within the region include (1) social and political instabilities; (2) insufficient resources and infrastructure for appropriate diagnosis, reporting, and implementation of control measures; (3) variation of livestock husbandry systems and their commingling with other livestock and wildlife; and (4) traditional cultural practices, including consumption of unpasteurized dairy products. Development of core interdisciplinary competencies is required for a true One Health–based endeavor against the disease. National awareness and educational programs addressing all population sectors from consumers to decision-makers seem to be the next logical, sustainable, and economically viable approach toward improving disease status in this region. In the present review, we describe the current situation of brucellosis in the ME, focusing on the major limitations and shortcomings regarding disease control. We propose a regional approach toward public awareness of brucellosis as the first step in mitigating the disease and discuss the potential benefits, and components of such a strategy, which can further be used as a model for other endemic zoonotic diseases.

The spatiotemporal distribution of human brucellosis in mainland China from 2007-2016

Background

Despite the considerable efforts made to address the issue of brucellosis worldwide, its prevalence in dairy products continues to be difficult to estimate and represents a key public health issue around the world today. The aim of the present study was to better understand the epidemiology of this disease in mainland China. We set out to investigate the yearly spatial distribution and possible hotspots of the disease.

Methods

Human brucellosis data from mainland China between 2007 and 2016 were collected from the China Information System for Disease Control and Prevention. A geographic information system ArcGIS10.3 (ESRI, Redlands) was used to identify potential changes in the spatial and temporal distribution of human brucellosis in mainland China during the study period. These distributions were evaluated using three-dimensional trend analysis and spatial autocorrelation analyse. A gravity-center was used to analyse the migration track of human brucellosis.

Results

A total of 399,578 cases of human brucellosis were reported during the 10-year study period. The monthly incidence of brucellosis in China demonstrates clear seasonality. Spring and summer are the peak seasons, while May is the peak month for brucellosis. Three-dimensional trend analysis suggests that brucellosis is on the rise from south to north, and that the epidemic situation in northern China is more severe. Between 2007 and 2016, the overall migration distance of the brucellosis incidence gravity-center was 906.43 km, and the direction was southwest. However, the overall gravity center of brucellosis was still in the northern part of China. In the global autocorrelation analysis, brucellosis in China demonstrated a non-random distribution between 2013 and 2014, with spatial autocorrelation (Z > 1.96, P < 0.05) and a clustering trend, while no clustering trend was found from 2007 to 2012 or from 2015 to 2016. In the local autocorrelation analysis, a Low-Low cluster phenomenon was found in the south of China in 2013 and 2014.

Conclusion

Human brucellosis remains a widespread challenge, particularly in northern China. The hotspots highlight potential high-risk areas which may require special plans and resources for monitoring and controlling the disease.

Brucella abortus contamination of camel milk in two Iranian regions

Brucella spp. commonly infect humans in various regions worldwide. Human brucellosis mainly spreads through the consumption of contaminated raw dairy products and meat from domestic livestock (water buffalo, goats, sheep, cattle, pigs and camels). In this regard, the origin and routes of transmission of this bacterium should be carefully determined in order to control the source of infection. This study aimed to evaluate the rate of Brucella spp. contamination of camel milk samples sent for analysis to the national brucellosis laboratory during 2018 in Iran. For this purpose, 96 milk samples from 96 dairy camel herds were randomly collected from two provinces and investigated for the presence of Brucella spp contaminations by both bacterial culture method and polymerase chain reaction (PCR). No clinical manifestation of brucellosis was reported in camels from which milk samples were collected. Using the culture method, three milk samples (3%) originating from two camels of Isfahan province (4%) and one camel from the Semnan province (2%), were contaminated with Brucella abortus. According to PCR analyses, B. abortus gene was detected in 14 (14.5%) milk samples, including 9 and 5 samples from Isfahan (18%) and Semnan (11%) province, respectively. PCR method revealed significant differences (p = 0.02) in the level of contamination with B. abortus between milk samples collected from two regions. These results represent the first report regarding the isolation of B. abortus from raw camel milk in Iran and highlight the importance to screen apparent healthy camels. Therefore, the consumption of raw camel milk may contribute to the spread of human brucellosis in endemic regions.

A Review of Zoonotic Pathogens of Dromedary Camels

Dromedary, or one-humped, camels Camelus dromedarius are an almost exclusively domesticated species that are common in arid areas as both beasts of burden and production animals for meat and milk. Currently, there are approximately 30 million dromedary camels, with highest numbers in Africa and the Middle East. The hardiness of camels in arid regions has made humans more dependent on them, especially as a stable protein source. Camels also carry and may transmit disease-causing agents to humans and other animals. The ability for camels to act as a point source or vector for disease is a concern due to increasing human demands for meat, lack of biosafety and biosecurity protocols in many regions, and a growth in the interface with wildlife as camel herds become sympatric with non-domestic species. We conducted a literature review of camel-borne zoonotic diseases and found that the majority of publications (65%) focused on Middle East respiratory syndrome (MERS), brucellosis, Echinococcus granulosus, and Rift Valley fever. The high fatality from MERS outbreaks during 2012-2016 elicited an immediate response from the research community as demonstrated by a surge of MERS-related publications. However, we contend that other camel-borne diseases such as Yersinia pestis, Coxiella burnetii, and Crimean-Congo hemorrhagic fever are just as important to include in surveillance efforts. Camel populations, particularly in sub-Saharan Africa, are increasing exponentially in response to prolonged droughts, and thus, the risk of zoonoses increases as well. In this review, we provide an overview of the major zoonotic diseases present in dromedary camels, their risk to humans, and recommendations to minimize spillover events.

A cross-sectional seroepidemiological study of camel (Camelus dromedarius) brucellosis and associated risk factors in the Sultanate of Oman

Brucellosis is a globally distributed and economically devastating zoonotic disease of multiple species, including camels. Human and livestock brucellosis is prevalent in Oman, especially in southern Dhofar governorates of Oman, where camels share habitat and have close contact with other susceptible species. We conducted a randomized cross-sectional sero-epidemiological study to investigate the seroprevalence of brucellosis in camels of Oman. The sera from 2,250 camels from 552 geographically marked farms were screened through Rose Bengal plate agglutination test and later confirmed by the competitive ELISA (COMPLIZA, VLA, UK). In total, nine [0.4%, confidence interval (CI) 0.4, 0.8] camels from eight (1.5%, CI 0.6, 2.8) herds were tested positive for brucellosis. The highest prevalence was recorded in Dhofar (3.7%, CI 1.4, 7.9) and the lowest in Sharqiyah (1.3%, CI 0.0, 7.2) governorate (p = 0.052). All seropositive camels were of local breed and females. Seroprevalence was higher (0.5%, CI 0.2, 1.0) in adults (>4 yr of age) as compared with young (≤4 yr of age) camels (0.2%, CI 0.0, 0.8). The results of binary logistic regression indicated that camel herds located in south (Dhofar) [odds ratio (OR) 6.39, CI 1.01, 40.67], practice of open replacement system (OR 14.49, CI 1.83, 114.51) and with history of abortions (OR 8.01, CI 1.34, 47.77) were more likely to test positive for brucellosis. We conclude that brucellosis is endemic at a low level in camels of Oman and a control strategy based upon test-and-slaughter/inclusion of camels in the current vaccination program after carefully planned vaccine evaluation studies could be considered to control it.

African Lineage Brucella melitensis Isolates from Omani Livestock

Brucellosis is a common livestock disease in the Middle East and North Africa, but remains poorly described in the region both genetically and epidemiologically. Traditionally found in goats and sheep, Brucella melitensis is increasingly recognized as infecting camels. Most studies of brucellosis in camels to date have focused on serological surveys, providing only limited understanding of the molecular epidemiology of circulating strains. We genotyped B. melitensis isolates from Omani camels using whole genome SNP assays and VNTRs to provide context for regional brucellosis cases. We identified a lineage of B. melitensis circulating in camels as well as in goats, sheep, and cattle in Oman. This lineage is genetically distinct from most genotypes from the Arabian Peninsula and from isolates from much of the rest of the Middle East. We then developed diagnostic assays that rapidly identify strains from this lineage. In analyses of genotypes from throughout the region, Omani isolates were genetically most closely related to strains from brucellosis cases in humans and livestock in North Africa. Our findings suggest an African origin for B. melitensis in Oman that has likely occurred through the trade of infected livestock. Moreover, African lineages of B. melitensis appear to be undersampled and consequently are underrepresented in genetic databases for Brucella. As we begin to more fully understand global genomic diversity of B. melitensis, finding and characterizing these unique but widespread lineages is essential. We predict that increased sampling of humans and livestock in Africa will reveal little known diversity in this important zoonotic pathogen.

Brucellosis in livestock and wildlife: zoonotic diseases without pandemic potential in need of innovative one health approaches

Human brucellosis remains the commonest zoonotic disease worldwide with more than 500 000 new cases annually. Understanding the biology of Brucella infections and the transmission patterns at the wildlife/livestock/human interface is of paramount importance before implementing any brucellosis control or eradication program in animals, even more so should interventions be justified within One Health. In addition to calling for transdisciplinary collaboration, One Health formally aims to conserve the environment and to promote the well-being of animals. In this opinion paper, the One Health approach of brucellosis is reviewed in the industrialized and the low and middle income countries, highlighting pitfalls and shortcomings of serological studies and discussing the role of urban and peri-urban farming for the re-emergence of brucellosis in the developing world. The role of wildlife as a potential reservoir is highlighted and different management strategies are discussed. Lastly, beyond its role in the control of brucellosis, the ethical dimension of culling wildlife to control disease emergence or spill-back of infections in livestock is discussed. Core transdisciplinary competencies such as values and ethics are critically important in guiding the development of One Health curricula and in continuing professional education, as they describe the knowledge, skills, and attitudes required to be effective. A conceptual framework needs to be developed from inception to knowledge translation. Importantly, transdisciplinary competencies should be developed as an adjunct to discipline-specific areas of expertise, not as a replacement. A profound understanding of the biology of infectious agents is and will always remain a pre-requisite for any sound One Health approach.

A study on some reproductive disorders in dromedary camel herds in Saudi Arabia with special references to uterine infections and abortion

Dromedary camels complaining from conception failure or abortion were investigated and their herders interviewed in Al Ahsa province, Kingdom of Saudi Arabia (KSA) during 2013 and 2015. The most important reproductive disorder according to the responders is uterine infection (60.2%) followed by obesity (22.3%) then physiological conditions (hormonal disturbances; 7.8%), adhesions (3.9%) and repeat breeders (2.9%). Of the camel herders, 78.6% reported previous occurrence of abortion in their herds and 46% reported abortion cases in the last season (2015/2016), while 21.4% reported no history of abortion. Most of the responders (97.1%) do not call a veterinarian for cases of abortion in their herds and 53.4% do not discard aborted materials. The majority of the herders (76.7%) deny that handling aborted materials or touching vaginal fluids can result in human infection, or replied they do not know. Uterine swab samples were collected and tested by PCR for seven potential pathogens and sera tested for antibodies against bovine viral diarrhea virus (BVDV) and Brucella. Five pathogens were identified in infected uterine samples, namely Coxiella burnetii (36%), Campylobacter spp. (27%), Brucella spp. (17%), Salmonella spp. (13%), and Chlamydia spp. (7%). Sero-prevalence of Brucella and BVDV was 8.2 and 29.1% in overall sera, respectively, and varies with regard to the region. The findings of the present study demonstrate that reproductive disorders dominated by uterine infections and abortions are widespread in dromedary camels in KSA.

Brucellosis in Sub-Saharan Africa: Current challenges for management, diagnosis and control

Brucellosis is a highly contagious zoonosis caused by bacteria of the genus Brucella and affecting domestic and wild mammals. In this paper, the bacteriological and serological evidence of brucellosis in Sub-Saharan Africa (SSA) and its epidemiological characteristics are discussed. The tools available for the diagnosis and treatment of human brucellosis and for the diagnosis and control of animal brucellosis and their applicability in the context of SSA are presented and gaps identified. These gaps concern mostly the need for simpler and more affordable antimicrobial treatments against human brucellosis, the development of a B. melitensis vaccine that could circumvent the drawbacks of the currently available Rev 1 vaccine, and the investigation of serological diagnostic tests for camel brucellosis and wildlife. Strategies for the implementation of animal vaccination are also discussed.

Human brucellosis in the Emirate of Abu Dhabi, United Arab Emirates, 2010-2015

Background

Worldwide, human brucellosis remains an important and widespread infection. In the past, there were limited data on the occurrence of human brucellosis in the United Arab Emirates and the reported incidence appeared to be low compared with similar areas. In 2009, a new web-based infectious disease surveillance system was introduced in the Emirate of Abu Dhabi. This paper reports data from this new system on human brucellosis for the 6 years 2010 to 2015.

Methods

A dataset was extracted for each case of human brucellosis reported to the notification system for the 6 year period January 2010 to December 2015. Annual brucellosis rates by age-group, gender, nationality and, geographical region were calculated and compared.

Results

A total of 480 cases of brucellosis were reported. The overall crude notification rate was 3 · 3 per 100,000 population but higher rates were seen in certain population subgroups notably expatriate males of working age in the Eastern Region (approximately 10 per 100,000) and UAE nationals of all ages and both genders in Abu Dhabi (between 4 -- 24 per 100,000).

Conclusions

These findings reflect environmental and behavioral factors linked to occupation and leisure time activities associated with the large number of small non-commercial livestock farms in Abu Dhabi. Controlling human brucellosis in these circumstances will be challenging.

Serological, molecular detection and potential risk factors associated with camel brucellosis in Pakistan

Brucellosis is one of the most important zoonoses in developing countries and was considered the most widespread zoonosis in the world. Brucellosis was reported in camels and has been reported from all camel-keeping countries.The present study was performed in three districts (Jhang, Chiniot, and Bhakkar) of Punjab province of Pakistan. A total of 200 camel (Camelus bactrianus) sera were collected using random and multistage cluster sampling from different areas. Fifty samples were collected from one organized governmental farm. One hundred fifty samples were collected randomly from nomadic/pastoral production systems. All sera were tested with Rose Bengal plate agglutination test (RBPT) and confirmed by ELISA. Genomic DNA was extracted from all serum samples and tested by real-time PCR. Various potential risk factors (season, rearing with other animals, and abortion or orchitis history) recorded through questionnaires were statistically analyzed by Chi-square test.In total, 5 % of investigated sera were positive by RBPT. Only 2 % of the camel sera were CELISA positive. Brucella abortus DNA was detected in 1.5 % of the investigated animals. Season, rearing of camels with other ruminants, abortion, and orchitis history were found to be statistically significant (p < 0.05) disease for determinants.Camel brucellosis is a zoonotic disease in the Pakistani Punjab with various risk factors maintaining and perpetuating its spread. Therefore, there is a need for implementing control measures and raising public health awareness in prevention of brucellosis in Pakistan.

Genotyping of Brucella melitensis strains from dromedary camels (Camelus dromedarius) from the United Arab Emirates with multiple-locus variable-number tandem repeat analysis

Camel brucellosis is a widespread zoonotic disease in camel-rearing countries caused by Brucella melitensis and Brucella abortus. The aim of this study was the first genetic analysis of B. melitensis strains isolated from dromedary camels (Camelus dromedarius) using multiple-locus variable-number tandem repeat analysis (MLVA). MLVA 16 and its MLVA 8 and MLVA11 subsets were used to determine the genotypes of 15 B. melitensis isolates from dromedary camels (11 strains) and other host species (4 strains) from the United Arab Emirates and the results were then compared to B. melitensis MLVA genotypes from other parts of the world. Five, including two novel genotypes were identified with MLVA 8. MLVA 16 further discriminated these five genotypes to ten variants. The eleven camel isolates clustered into four main genetic groups within the East-Mediterranean and African clades and this clustering correlated with the geographic origin of the hosts (United Arab Emirates, Kingdom of Saudi Arabia and Sudan) and the date of their isolation. The camel strains were also genetically related to strains isolated from wild and domestic ruminants from their close habitat or from other parts of the world. Although limited number of strains were analysed, based on our data imported animals from foreign countries, local small ruminants and wildlife species are hypothesized to be the main sources of camel brucellosis in the United Arab Emirates. MLVA was successfully applied to determine the epidemiological links between the different camel B. melitensis infections in the United Arab Emirates and it can be a beneficial tool in future disease control programs.

Complete genome sequence of Staphylococcus aureus, strain ILRI_Eymole1/1, isolated from a Kenyan dromedary camel

We report the genome of a Staphylococcus aureus strain (ILRI_Eymole1/1) isolated from a nasal swab of a dromedary camel (Camelus dromedarius) in North Kenya. The complete genome sequence of this strain consists of a circular chromosome of 2,874,302 bp with a GC-content of 32.88 %. In silico annotation predicted 2755 protein-encoding genes and 76 non-coding genes. This isolate belongs to MLST sequence type 30 (ST30). Phylogenetic analysis based on a subset of 283 core genes revealed that it falls within the human clonal complex 30 (CC30) S. aureus isolate cluster but is genetically distinct. About 79 % of the protein encoding genes are part of the CC30 core genome (genes common to all CC30 S. aureus isolates), ~18 % were within the variable genome (shared among multiple but not all isolates) and ~ 3 % were found only in the genome of the camel isolate. Among the 85 isolate-specific genes, 79 were located within putative phages and pathogenicity islands. Protein encoding genes associated with bacterial adhesion, and secretory proteins that are essential components of the type VII secretion system were also identified. The complete genome sequence of S. aureus strain ILRI_Eymole1/1 has been deposited in the European Nucleotide Archive under the accession no LN626917.1.

Brucellosis update in Libya and regional prospective

Brucellosis is a global bacterial zoonosis responsible for high morbidity in humans and significant livestock economic losses. While brucellosis remains a public health concern worldwide, its global geographic distribution is variable, largely due to different management schemes; however, paucity of information renders the status of brucellosis unclear and incomplete in many countries, especially those with low income and under-developed infrastructure. This short article summarizes and discusses recent important updates on brucellosis from the North African countries, with a particular brief emphasis on the current status and recent updates in Libya.

Brucellosis as an emerging threat in developing economies: lessons from Nigeria

Nigeria is the most populous country in Africa, has a large proportion of the world's poor livestock keepers, and is a hotspot for neglected zoonoses. A review of the 127 accessible publications on brucellosis in Nigeria reveals only scant and fragmented evidence on its spatial and temporal distribution in different epidemiological contexts. The few bacteriological studies conducted demonstrate the existence of Brucella abortus in cattle and sheep, but evidence for B. melitensis in small ruminants is dated and unclear. The bulk of the evidence consists of seroprevalence studies, but test standardization and validation are not always adequately described, and misinterpretations exist with regard to sensitivity and/or specificity and ability to identify the infecting Brucella species. Despite this, early studies suggest that although brucellosis was endemic in extensive nomadic systems, seroprevalence was low, and brucellosis was not perceived as a real burden; recent studies, however, may reflect a changing trend. Concerning human brucellosis, no studies have identified the Brucella species and most reports provide only serological evidence of contact with Brucella in the classical risk groups; some suggest brucellosis misdiagnoses as malaria or other febrile conditions. The investigation of a severe outbreak that occurred in the late 1970s describes the emergence of animal and human disease caused by the settling of previously nomadic populations during the Sahelian drought. There appears to be an increasing risk of re-emergence of brucellosis in sub-Saharan Africa, as a result of the co-existence of pastoralist movements and the increase of intensive management resulting from growing urbanization and food demand. Highly contagious zoonoses like brucellosis pose a threat with far-reaching social and political consequences.