Prevalence of brucellosis in livestock of African and Asian continents: A systematic review and meta-analysis

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.

Molecular Testing of Zoonotic Bacteria in Cattle, Sheep, and Goat Abortion Cases in Botswana

Abortion is one of the major causes of economic losses in livestock production worldwide. Because several factors can lead to abortion in cattle, sheep and goats, laboratory diagnosis, including the molecular detection of pathogens causing abortion, is often necessary. Bacterial zoonotic diseases such as brucellosis, coxiellosis, leptospirosis, and listeriosis have been implicated in livestock abortion, but they are under diagnosed and under-reported in most developing countries, including Botswana. This study applied a recently developed multiplex high-resolution melting analysis technique, coupled with singleplex qPCR assays, to investigate abortions in livestock in Botswana, using 152 samples from cattle, sheep, and goat abortion cases. Brucella spp. were the most frequent pathogen detected, with an overall frequency of 21.1%, followed by Coxiella burnetii with 19.1%. Listeria monocytogenes and Leptospira spp. were not detected in any of specimens samples investigated. Mixed infections with Brucella spp. and C. burnetii were observed in 35% specimes examined. There was a good agreement between the multiplex qPCR-HRM and singleplex qPCR for detecting Brucella spp. and C. burnetii. This study is the first report on the syndromic testing of abortion-causing pathogens in Botswana. It shows the importance of molecular methods in the differential diagnosis of abortion-causing diseases in domestic ruminants.

Human and animal brucellosis and risk factors for human infection in Ethiopia: a systematic review and meta-analysis (2015-2024)

BACKGROUND AND OBJECTIVE

Brucellosis is a neglected zoonotic disease caused by Brucella species. Unlike most developed nations, the problem of brucellosis in Ethiopia remains a public and animal health concern. This study was conducted to determine the magnitude of brucellosis in animals (mainly cattle, sheep, goats, dogs and camels) and humans, and to identify the risk factors for human brucellosis.

METHODOLOGY

The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed to conduct this systematic review and meta-analysis, which was performed from May 2024 to July 2024. Academic databases such as PubMed, ScienceDirect, Scopus, PubMed Central, Web of Science, and Google Scholar were searched to identify articles focusing on brucellosis in humans and animals in Ethiopia. Data extraction was performed according to predefined inclusion and exclusion criteria. The included articles were appraised using the appraisal tool for cross-sectional studies to assess study quality. Publication bias and small study effects were examined using funnel plot observation and Egger's test, respectively. Statistical analysis was conducted using R software version 4.4.1.

RESULTS

Thirty-nine articles published between 2015 and 2024 were included in the final analysis from a total of 1,427 identified articles. The overall pooled seroprevalence of brucellosis was 5.0% (95% CI: 3.0, 6.0). The seroprevalence of brucellosis was higher in humans at 6.9% (95% CI: 4.9, 8.8) and lower in cattle at 3.5% (95% CI: 2.2, 4.7). There was high heterogeneity in the reports of brucellosis seroprevalence between studies (τ² = 0.0038, H² = 255.9, I² = 99.61%, Q-test = 1954.99, df = 56, p ≤ 0.001). Laboratory tests and study location were identified as factors contributing to potential sources of variation in the pooled seroprevalence. Drinking raw milk from aborted animals, touching aborted materials or fetuses, and occupation were among the risk factors for human brucellosis. No publication bias or small study effects were detected.

CONCLUSION

The findings indicate that brucellosis continues to pose a significant zoonotic threat, particularly to humans, where the seroprevalence is notably higher than in animals. These results highlight the need for targeted public health interventions and greater awareness to reduce the incidence of brucellosis, especially among high-risk populations.

Biological Hazards and Indicators Found in Products of Animal Origin in Cambodia from 2000 to 2022: A Systematic Review

Biological hazards in products of animal origin pose a significant threat to human health. In Cambodia, there are few comprehensive data and information on the causes of foodborne diseases or risks. To date, there has been no known published study similar to this review. This systematic review is aimed to investigate the prevalence of biological hazards and their indicators in products of animal origin from 2000 to 2022. The main objective of this study was also to contribute to strengthening Cambodia's food control system. This review followed the established "Preferred Reporting Items for Systematic Reviews and Meta-Analyses" (PRISMA) guidelines. In total, 46 studies were retained for complete review. Most studies (n = 40) had been conducted by or with external researchers, reflecting the under-resourcing of the National Food Control System in terms of surveillance; areas outside the capital were relatively understudied, reflecting evidence found in Ethiopia and Burkina Faso. Five categories of hazards were reported with the highest number of studies on fish parasites. Marketed fish, often originating from different countries, had a higher mean value of parasite prevalence (58.85%) than wild-caught fish (16.46%). Viral pathogens in bat meat presented a potential spillover risk. Many potentially important hazards had not yet been studied or reported (e.g., Norovirus, Shigella, toxin-producing Escherichia coli, and Vibrio cholerae). The findings of our review highlighted significant urgencies for national competent authorities to enhance food hygiene practices along the production chain, tackle import control, and enforce the implementation of a traceability system, alongside more research collaboration with neighboring countries and key trading partners. It is crucial to conduct more extensive research on food safety risk analysis, focusing on the identification and understanding of various biological hazards and their associated risk factors in food.

A meta-analysis of livestock brucellosis prevalence in Indonesia

Indonesia has a long history of livestock brucellosis, but the overall pooled prevalence remains unclear. This study aims to determine the pooled estimated prevalence of livestock brucellosis in Indonesia using the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. Five databases were searched and screened using predefined inclusion and exclusion criteria. Data from included studies were extracted and analyzed using a random effects model in R 4.3.0 for pooled estimated prevalence, subgroup meta-analysis, and meta-regression. Publication bias and sensitivity tests were conducted using Egger's test, funnel plot, trim and fill plot, and leave-one-out. The screening process identified 46 included studies, representing 47,057 samples for brucellosis testing. The pooled estimated prevalence for livestock brucellosis was 3.25% (95% CI, 1.81%-5.78%) with high heterogeneity (Q = 2130.91, p = 0, I2=98%). Subgroup meta-analysis indicated no significant difference in the prevalence of livestock brucellosis across the main islands in Indonesia (p = 0.44) and across provinces in Sulawesi Island (p = 0.83), but significant differences were found among provinces in Java (p < 0.01). The subgroup meta-analysis based on animal type showed no significant difference between cattle, small ruminants, and pig brucellosis estimated prevalence (p = 0.26). Between serological tests, no significant difference was found (p = 0.77). Meta-regression showed no significant difference in brucellosis prevalence from 1988-2023. Egger's test and funnel plot showed publication bias. Trim and fill test indicated 21 studies should be added. As most studies were conducted in Java and Sulawesi Islands, caution should be exercised in interpreting the results, emphasizing the necessity of increasing the study of brucellosis in other regions.

Emerging zoonotic diseases in Southeast Asia in the period 2011-2022: a systematic literature review

As COVID-19 has shown, pandemics and outbreaks of emerging infections such as Zika, Nipah, monkeypox and antimicrobial-resistant pathogens, especially emerging zoonotic diseases, continue to occur and may even be increasing in Southeast Asia. In addition, these infections often result from environmental changes and human behaviour. Overall, public health surveillance to identify gaps in the literature and early warning signs are essential in this region. A systematic review investigated the prevalence of emerging zoonotic diseases over 11 years from 2011 to 2022 in Southeast Asia to understand the status of emerging zoonotic diseases, as well as to provide necessary actions for disease control and prevention in the region. During the 2011-2022 period, studies on pigs, poultry, ruminants, companion animals and wildlife in Southeast Asia were reviewed thoroughly to assess the quality of reporting items for inclusion in the systematic review. The review was performed on 26 studies of pigs, 6 studies of poultry, 21 studies of ruminants, 28 studies of companion animals and 25 studies of wildlife in Southeast Asia, which provide a snapshot of the prevalence of the emerging zoonotic disease across the country. The findings from the review showed that emerging zoonotic diseases were prevalent across the region and identified a few zoonotic diseases associated with poultry, mainly stemming from Cambodia and Vietnam, as high priority in Southeast Asia.Clinical relevance: Appropriate prevention and control measures should be taken to mitigate the emerging zoonotic diseases in Southeast Asia.

Bovine Brucellosis: First Comprehensive Evaluation from Hamedan, an Endemic Area in Iran

Brucellosis is an infectious zoonotic disease. The disease is one of the major concerns in developing societies due to its great importance for public health and economic losses in the animal industry. The principal target of the study was to detect the prevalence of brucellosis and associated risk factors in cattle from Hamedan (western Iran) using different laboratory techniques. In 2020, blood samples from 900 cattle were obtained to detect brucellosis prevalence in the region. After screening by the modified Rose Bengal plate test, the positive samples were reevaluated using the Wright standard tube agglutination test (SAT), 2-Mercaptoethanol (2-ME), and Enzyme-linked immunosorbent assay. Serology-positive samples were confirmed by culturing bacteria from the lymph nodes and detecting Brucella DNA using specific primers, the BCSP31 target gene, and the IS711 locus. Brucellosis was detected in 1.88% (17/900, 95% CI 1-2.76%) of animals. The high prevalence of brucellosis was observed in female animals (2.77%, p = 0.947), 2-4 years old animals (2.88%, p = 0.994), Holsteins (5.69%, p = 0.989), farm animals (6.49%, p = 0.999), and animals with a history of vaccination against brucellosis (3.04%, p = 0.915). In addition, there was no positive sample in October and December, and also the highest prevalence rate was found in September (5.33%, p = 0.970). There was no statistically significant relationship between the variables and the rate of brucellosis. There were similar results between the different applied laboratory methods. The minimum and maximum levels of titer in the SAT method were + 2/80 and + 2/320, respectively. The rates for 2-ME were + 2/40 and + 4/160. Out of 17 positive samples, 2 were confirmed for B. melitensis and 15 for B. abortus. Notably, no sample showed co-infection of both B. abortus and B. melitensis. This study represents the first comprehensive evaluation of cattle brucellosis in Hamedan. Through molecular evaluation, the presence of Brucella spp. was identified in the seropositive samples. Among the cattle samples, the primary species isolated and confirmed was B. abortus. This finding shed light on the prevalence and distribution of Brucella species in the region, providing crucial insights for future disease management and control efforts. Considering the specificity of the used genes to detect bacteria, molecular biology can be a safe and rapid technique for diagnosing brucellosis, especially in cases without conclusive results. Regular screening of animals and culling seropositive animals are highly recommended; these affect the control of disease at the herd level.

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.

Assessing and Prioritizing Zoonotic Diseases in Punjab, India: A One Health Approach

Zoonotic diseases have a significant impact on both human and animal health globally. The present study was planned to prioritize the zoonoses in Punjab state of India. To develop a zoonotic disease prioritization scoring system, a comprehensive approach has been taken, including literature review, key person interviews with animal health experts (n = 12) and medical professionals (n = 7), and nine focus group discussions (FGDs) with veterinary academicians, medical professionals, and field veterinary doctors. The scoring system comprises of seven major criteria, each assigned a weightage score (ws): prevalence/incidence of the disease (ws = 0.20), severity of illnesses in humans (ws = 0.18), epidemic potential (ws = 0.16), socio-economic burden (ws = 0.16), availability of effective control and prevention measures (ws = 0.15), inter-sectoral collaborations (ws = 0.1), and bioterrorism potential (ws = 0.05). The finalized scoring system, accompanied by a list of 15 selected zoonotic diseases, was implemented among a group of 23 professionals engaged in zoonoses research (n = 7), animal health (n = 10), and medical health (n = 6) to determine their prioritization. The zoonotic diseases prioritized for the Punjab (India) included, Brucellosis (0.70) > Rabies (0.69) > Anthrax (0.64) > Leptospirosis (0.62) = Toxoplasmosis (0.62) = Highly Pathogenic Avian Influenza (HPAI) (0.62) > Bovine tuberculosis (0.61) > Q fever (0.60) > Cysticercosis (0.59) > Listeriosis (0.58) > Crimean-Congo haemorrhagic fever (CCHF) (0.57) > Japanese encephalitis (0.56) = Echinococcosis (0.56) > Dermatophytosis (0.53) > and Scrub typhus (0.48), respectively. Higher priority is suggested for endemic zoonoses (e.g., brucellosis and rabies) as compared to those with epidemic potential (e.g., CCHF, HPAI etc.) in Punjab. Results of the current study will help in the development of targeted control and prevention strategies for zoonotic diseases in Punjab and other geographical regions facing similar challenges.

Brucellosis and One Health: Inherited and Future Challenges

One Health is the collaborative efforts of multiple disciplines to attain optimal health for people, animals and the environment, a concept that historically owes much to the study of brucellosis, including recent political and ethical considerations. Brucellosis One Health actors include Public Health and Veterinary Services, microbiologists, medical and veterinary practitioners and breeders. Brucellosis awareness, and the correct use of diagnostic, epidemiological and prophylactic tools is essential. In brucellosis, One Health implementation faces inherited and new challenges, some aggravated by global warming and the intensification of breeding to meet growing food demands. In endemic scenarios, disease awareness, stakeholder sensitization/engagement and the need to build breeder trust are unresolved issues, all made difficult by the protean characteristics of this zoonosis. Extended infrastructural weaknesses, often accentuated by geography and climate, are critically important. Capacity-building faces misconceptions derived from an uncritical adoption of control/eradication strategies applied in countries with suitable means, and requires additional reference laboratories in endemic areas. Challenges for One Health implementation include the lack of research in species other than cattle and small ruminants, the need for a safer small ruminant vaccine, the need to fill in the infrastructure gap, the need for realistic capacity-building, the creation of reference laboratories in critical areas, and the stepwise implementation of measures not directly transposed from the so-called developed countries.

Accessibility of the three-year comprehensive prevention and control of brucellosis in Ningxia: a mathematical modeling study

BACKGROUND

Brucellosis is a chronic zoonotic disease, and Ningxia is one of the high prevalence regions in China. To mitigate the spread of brucellosis, the government of Ningxia has implemented a comprehensive prevention and control plan (2022-2024). It is meaningful to quantitatively evaluate the accessibility of this strategy.

METHODS

Based on the transmission characteristics of brucellosis in Ningxia, we propose a dynamical model of sheep-human-environment, which coupling with the stage structure of sheep and indirect environmental transmission. We first calculate the basic reproduction number [Formula: see text] and use the model to fit the data of human brucellosis. Then, three widely applied control strategies of brucellosis in Ningxia, that is, slaughtering of sicked sheep, health education to high risk practitioners, and immunization of adult sheep, are evaluated.

RESULTS

The basic reproduction number is calculated as [Formula: see text], indicating that human brucellosis will persist. The model has a good alignment with the human brucellosis data. The quantitative accessibility evaluation results show that current brucellosis control strategy may not reach the goal on time. "Ningxia Brucellosis Prevention and Control Special Three-Year Action Implementation Plan (2022-2024)" will be achieved in 2024 when increasing slaughtering rate [Formula: see text] by 30[Formula: see text], increasing health education to reduce [Formula: see text] to 50[Formula: see text], and an increase of immunization rate of adult sheep [Formula: see text] by 40[Formula: see text].

CONCLUSION

The results demonstrate that the comprehensive control measures are the most effective for brucellosis control, and it is necessary to further strengthen the multi-sectoral joint mechanism and adopt integrated measures to prevention and control brucellosis. These results can provide a reliable quantitative basis for further optimizing the prevention and control strategy of brucellosis in Ningxia.