Brucellosis in Livestock: A One Health Challenge for Rural Economies

Brucellosis remains one of the world’s most persistent zoonotic diseases, exerting a heavy toll on animal health, public health, and economic stability, particularly in agrarian economies. Caused by bacteria of the Brucella genus, the disease affects a wide range of domestic animals (cattle, goats, sheep, and buffaloes) causing reproductive disorders such as abortions, retained placentas, infertility, and decreased milk production. These outcomes severely diminish farm productivity, leading to significant economic losses for smallholders and commercial farmers alike. In regions where livestock serve as the backbone of rural livelihoods, brucellosis erodes household income, compromises food availability, and undermines long-term development efforts.

For humans, the disease commonly known as undulant or Malta fever is transmitted through direct contact with infected animals, contaminated environments, or the consumption of unpasteurized dairy products. Symptoms such as recurrent fever, joint pain, and fatigue can become chronic if untreated, reducing labor productivity and straining rural healthcare systems. In countries where animal vaccination and milk pasteurization programs are inconsistently implemented, the risk of human infection remains particularly high.

The complex epidemiology of brucellosis highlights the need for a One Health approach, integrating veterinary, medical, and environmental interventions. Strengthening animal vaccination coverage, improving farm biosecurity, enforcing dairy hygiene standards, and conducting community education campaigns are essential steps toward control. Simultaneously, enhanced surveillance and diagnostic capacity can help identify outbreaks early and prevent cross-species transmission.

Ultimately, combating brucellosis requires not only medical and veterinary solutions but also social and institutional coordination. By fostering collaboration between farmers, veterinarians, public health agencies, and policymakers, nations can move toward eliminating this ancient yet still formidable disease, protecting both livelihoods and lives while advancing sustainable rural development.

Brucellosis: Etiology and Epidemiology

Brucellosis is a contagious bacterial zoonosis caused by Brucella species, small Gram-negative, non-motile cocco-bacilli that infect a wide range of domestic and wild animals. These bacteria are facultative intracellular pathogens, capable of surviving and multiplying within host macrophages, which makes eradication particularly difficult. The disease’s epidemiology is closely tied to its host preferences: Brucella abortus predominantly infects cattle and buffaloes, Brucella melitensis, the most pathogenic species for humans, affects goats and sheep, while Brucella suis is commonly associated with pigs and certain wildlife reservoirs (Godfroid et al., 2011). Each species adapts to specific ecological and husbandry conditions, influencing regional disease dynamics.

Transmission among animals primarily occurs through direct contact with infected materials such as aborted fetuses, placental tissues, and genital discharges. Environmental contamination plays a major role, as the bacteria can survive for weeks to months in cool, moist conditions in soil, manure, and water sources. Animals can become infected by ingesting contaminated feed or water or through mucosal exposure during parturition. Vertical transmission through milk or in utero infection also perpetuates herd-level persistence. Once infected, animals often remain chronic carriers, intermittently shedding bacteria and acting as reservoirs for ongoing transmission.

The global burden of brucellosis is substantial, with an estimated 500,000 new human cases annually (Pappas et al., 2006), though the true number is likely much higher due to widespread underreporting and misdiagnosis. The disease remains endemic across the Mediterranean Basin, the Middle East, South and Central Asia, Latin America, and parts of Africa. In many developing countries, weak surveillance systems, lack of vaccination coverage, and informal livestock trading perpetuate its spread. Understanding the etiology and epidemiology of brucellosis is therefore critical to designing targeted prevention, control, and eradication strategies under a One Health framework that bridges veterinary and human health sectors.

Impact of Brucellosis in Livestock and Humans

Brucellosis exerts a heavy toll on livestock productivity and rural livelihoods worldwide. In animals, the disease primarily targets the reproductive system, leading to abortions, stillbirths, retained placentas, and infertility. Such reproductive failures not only reduce herd size but also compromise genetic improvement programs designed to enhance productivity. In dairy herds, infection with Brucella species causes a significant drop in milk yield estimated to be at least 20% in affected animals (McDermott & Arimi, 2002) which severely undermines farm profitability and national milk supply. Moreover, chronic infections reduce fertility rates and animal longevity, while infected males may suffer from orchitis and epididymitis, further hindering breeding potential. In draught animals, fatigue and reduced work capacity translate into lowered agricultural productivity, exacerbating economic losses, particularly for smallholder farmers who depend on livestock for both income and labor. On a macroeconomic scale, brucellosis can also result in trade restrictions, limiting the export of livestock, dairy products, and genetic material, and imposing costly barriers to international markets.

Beyond livestock, brucellosis represents a serious zoonotic threat to public health. Humans typically contract the infection through direct contact with infected animals or by consuming unpasteurized milk, cheese, or other dairy products. Those most at risk include veterinarians, farmers, slaughterhouse workers, and laboratory technicians. Human brucellosis, commonly known as undulant fever, presents with intermittent fever, weakness, muscle and joint pain, and night sweats, often mimicking other febrile illnesses, leading to delayed diagnosis. Without timely antibiotic treatment, the disease can progress to chronic forms involving arthritis, endocarditis, and neurological complications (Franc et al., 2018). These prolonged illnesses reduce worker productivity and impose heavy medical and social costs. Thus, controlling brucellosis in livestock is not only vital for agricultural sustainability but also essential for protecting human health, food safety, and economic development under the One Health paradigm.

Diagnosis, Control, and Prevention of Brucellosis

Accurate and timely diagnosis forms the foundation of any effective brucellosis control program. Given the disease’s complex epidemiology and its ability to establish chronic infections, diagnostic precision is vital for preventing widespread transmission within and between herds. In most field settings, serological testing remains the primary diagnostic tool. The Rose Bengal Plate Test (RBT) is widely used as a rapid and inexpensive screening method, allowing for large-scale herd surveillance. However, because RBT can yield false positives due to cross-reactivity with other bacteria, confirmatory tests are essential. Advanced assays such as the Competitive Enzyme-Linked Immunosorbent Assay (cELISA) and the Fluorescence Polarization Assay (FPA) offer greater specificity and reliability, especially for international trade certification and disease control programs (Godfroid et al., 2011).

Molecular diagnostic methods, particularly Polymerase Chain Reaction (PCR), have revolutionized disease detection by enabling the identification of Brucella DNA with high sensitivity and specificity. PCR techniques can also differentiate between vaccine strains and wild-type infections, an essential capability in regions where vaccination is widely practiced. Despite their accuracy, molecular methods remain underutilized in many developing countries due to high costs and limited laboratory infrastructure. The gold standard for confirmation, bacterial culture, provides definitive identification and strain typing but requires Biosafety Level 3 facilities, specialized personnel, and strict safety protocols to protect laboratory workers. These constraints underscore the urgent need for affordable, portable diagnostic kits and improved biosafety infrastructure, particularly in endemic regions.

Controlling and preventing brucellosis in livestock demands a comprehensive, multifaceted strategy centered on vaccination, sound herd management, and strict biosecurity. Vaccination remains the cornerstone of long-term control, with live attenuated strains such as B. abortus S19 for cattle, B. melitensis Rev.1 for small ruminants, and B. abortus RB51 for differentiation between vaccinated and infected animals (Schurig et al., 2002). In parallel, biosecurity practices, including the quarantine and testing of new stock, prompt culling of infected animals, and safe disposal of aborted materials are essential to prevent disease spread. The pasteurization of milk and use of personal protective equipment for farm and veterinary workers are equally vital public health measures to break the zoonotic transmission cycle.

Ultimately, the persistent challenge of brucellosis reinforces the importance of the One Health approach, which recognizes that human, animal, and environmental health are deeply interconnected. Effective control cannot be achieved through veterinary interventions alone; it requires collaboration among medical professionals, agricultural authorities, and environmental agencies. Targeting the infection at its animal source remains the most efficient and cost-effective strategy. Through integrated surveillance, vaccination campaigns, and cross-sectoral education, nations can significantly reduce the burden of brucellosis, safeguarding both rural livelihoods and public health.

Recommendations for the Control and Eradication of Brucellosis

Brucellosis remains a formidable obstacle to sustainable livestock production and rural development, particularly in endemic regions across Asia, Africa, and the Mediterranean. The disease not only undermines animal productivity but also threatens public health and national economies through trade losses and medical expenditures. Despite the availability of effective vaccines and diagnostic tools, the persistence of brucellosis is largely due to weak surveillance systems, fragmented control efforts, and limited community awareness. Therefore, an integrated, long-term, and well-coordinated strategy is essential for its effective control.

Strengthened vaccination programs must form the backbone of disease prevention. Mass immunization of cattle and small ruminants in high-risk areas should be systematically implemented and monitored to ensure coverage and compliance. Alongside vaccination, enhanced surveillance systems using modern diagnostic tools such as PCR and ELISA are crucial for mapping disease prevalence and guiding targeted interventions.

On farms, strict biosecurity measures, including controlled animal movement, proper sanitation, and safe disposal of infected materials must be enforced. Public education campaigns should emphasize the dangers of consuming unpasteurized milk and the importance of safe animal handling practices.

Equally important is the establishment of a functional One Health framework, fostering collaboration between veterinary, human health, and environmental sectors. Joint surveillance, data sharing, and coordinated outbreak responses can ensure early detection and swift containment.

By prioritizing education, vaccination, surveillance, and inter-sectoral coordination, countries can substantially reduce the burden of brucellosis. These actions will not only protect animals and human health but also enhance rural livelihoods, food security, and economic stability paving the way toward sustainable agricultural and public health systems.

Conclusion

Brucellosis remains one of the most enduring and economically devastating zoonotic diseases affecting both livestock and humans worldwide. Its persistence in endemic regions reflects not only biological resilience but also systemic challenges limited diagnostic capacity, inadequate vaccination coverage, and weak intersectoral coordination. The disease’s dual burden on animal productivity and human health continues to undermine rural livelihoods, constrain agricultural trade, and impede progress toward sustainable development.

The path toward brucellosis eradication demands a comprehensive and unified approach anchored in the One Health framework. This includes strengthening vaccination programs for cattle and small ruminants, improving surveillance and reporting systems, and ensuring rapid diagnosis through accessible and reliable testing methods. Farmer education and community engagement are equally critical to enhance compliance with biosecurity measures and promote safe dairy consumption practices.

Governments and international partners must also invest in veterinary infrastructure, research, and policy enforcement to sustain long-term control efforts. Eradicating brucellosis is not merely a veterinary challenge, it is economic, public health, and social imperative. Through coordinated action, nations can move closer to a future where livestock are healthy, rural communities are resilient, and the threat of zoonotic transmission is effectively contained, ensuring food safety and sustainable rural prosperity.

References: Godfroid et al; Pappas et al; McDermott & Arimi; Franc et al; Schurig et al.

Please note that the views expressed in this article are of the author and do not necessarily reflect the views or policies of any organization.

The writers are affiliated with the Faculty of Veterinary Sciences, University of Agriculture, Faisalabad Pakistan and can be reached at sanoakhtar@gmail.com

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