There are a number of bacterial, viral, and parasitic diseases present at the Wildlife/livestock/human interface. Brucellosis is a zoonotic disease of importance and highly prevalent in sub-Saharan Africa. The important Brucella species at the wildlife/livestock/human interface are Brucella arbortus, Brucella suis, and Brucella melitensis. These species have been isolated from humans, livestock (cattle and goats), and wildlife (African buffalo and giraffe). A lot of studies indicated that density, herd size, age of cow, reduced veterinary services like vaccination programs, and geographical area are associated with Brucella prevalence. Studies in developing countries have indicated that the disease is more prominent in the both commercial and communal farming sectors. Access and consumption of contaminated foods and/or occupational exposure remain the significant source of infection to humans. The pathogen transmission of brucellosis is bidirectional in nature; hence, for control efforts to be successful, cooperation is required between livestock owners, animal health officials, and wildlife managers. Globally, trend is moving toward focusing on “one health,” which recognizes that human, animal (both domestic and wild), and ecosystems are tightly linked. The successful management of disease requires an integrated approach where efforts are focused in concert across these domains. Climate change, increased human populations, and increased interaction at wildlife/livestock/human interface have resulted in the change of brucellosis dynamics.
- wildlife/livestock/human interface
- emerging diseases
- zoonotic diseases
- disease management
Interest in the epidemiology of emerging diseases of humans and livestock as they relate to wildlife has increased greatly over the past several decades . The importance of wildlife in the emergence of livestock and human brucellosis is due to multiple changes occurring within wildlife, livestock, and human populations . The epidemiology of infections and diseases is highly dependent on several factors within, or in the interfaces between, human, livestock, or wildlife populations. Land use changes being speared by humans, which include encroachment into wildlife habitat, continue to increase, along with more intensified livestock production practices. This scenario is favorable to the spread of brucellosis. The alteration of wildlife population demographics bring in a new dimension in the epidemiology of brucellosis, e.g., increasing African buffalo population in Southern Africa, which in turn increases the chances of potential for contact and
Human and animal health populations are pivotal and important for economic development, prosperity, and stability. Infectious diseases like brucellosis affect health and reproductivity of livestock, thereby greatly reducing its value and opportunities for trade. Brucellosis is a zoonosis and a disease of veterinary and public health significance worldwide. It is a disease that infects multiple species even in marine ecosystem, and it is also found in many continents. The incidences and prevalence of the disease vary widely from country to country. Brucellosis prevalence is relatively high in Africa, Latin American, and Asian countries. It is the disease of sexually matured animals with predilection for placentas, fetal fluids, and testes of male animals (OIE 2014). It is caused by bacteria of the genus
Interface spaces allow people, livestock, and wildlife to share space and resources in semi-arid landscapes, especially transfrontier conservation areas (TFCAs) in Africa (see Figure 1). The coexistence of domestic herbivores and wild animals has its advantages and disadvantages, for example, ecotourism, but one of the major consequences is the risk of pathogen transmission. The risk at the interface threatens local livelihoods depending on animal production, ecotourism, public health in the case of brucellosis, national economies in the context of transboundary animal diseases, and the success of integrated conservation and development initiatives . Globally, the role of wildlife in livestock diseases is expected to increase  in conjunction with human population growth, which is expected to reach 9 billion by 2030. Increased demand for animal protein will further increase potentially infectious contacts between livestock and wildlife, leading to an increased potential for zoonotic diseases (brucellosis) to emerge. The changes in the dynamics will result in challenges that will require an improved understanding of the ecology of pathogens at the wildlife/livestock/human interface along with the development of tools and mitigations to manage these pathogens.
2. Brucella species associated with the interface
The members of the genus
The causative agent of brucellosis in swine, hares (
3. Epidemiology of brucellosis at the interface
Areas with high population density result in increased infections in humans, while transmission from livestock to humans is more likely in areas with high human and herd/farm density, especially where humans and livestock live in close proximity, as is often the case in developing countries . The discovery of strains in marine animals has increased the complexity of interactions between humans and other animals due to the fact that each type of species discovered has distinctive epidemiological features. This overall affects the epidemiology of brucellosis. The epidemiology of brucellosis is influenced by several factors, such as livestock production type, herd size, interaction with wildlife, ecological, and socioeconomic factors . A lot of work done indicated that density, herd size, age of cow, reduced veterinary services like vaccination programs, and geographical area are associated with high
Access and consumption of contaminated foods and/or occupational exposure remains the significant source of infection to humans. Infection occurs through the skin (intact or abraded), inhalation, or conjunctiva. The main source of infection for the public is through the ingestion of contaminated dairy product, especially raw milk, in developing countries. The bacteria can also be transmitted in raw or undercooked meat from infected animals. This factor poses a greater threat at TFCAs since communities have access to game meat through illegal means, e.g., poaching. Abortion and infertility are the predominant clinical signs in ruminants 
Studies in the mid-1990s found
4. Brucellosis in human at the interface
About 58% of the infectious diseases of humans are estimated to be zoonoses, and they comprise almost three-quarters of emerging infectious diseases . Brucellosis is directly and indirectly transmitted from animals to humans. Human-to-human transmissions are rare, and small ruminants are the main reservoir for human cases. Humans can be infected directly by contact with the conjunctival or oronasal mucosae of infected animals, or indirectly by the ingestion of contaminated animal products (mainly dairy products) . Naturally acquired brucellosis in humans almost always comes from the animal reservoirs, although very few cases of human to human transmission have been reported . Brucellosis is considered an occupational disease of adults, but there are now several reports of childhood brucellosis in literature . Human brucellosis is predominantly an occupational disease; professions in direct contact with livestock (farmers, butchers, veterinarians, laboratory personnel, etc.) are those at higher risk. In humans, both acute and chronic forms of the disease with variable clinical manifestations were found. Disease can occur at any age and affect any organ system .
Low reporting figures and lack of resources have resulted in the global incidence of human brucellosis not being accurately recorded. Hence, great variations exist between different geographic areas even within the same country. Although the reported incidence in most developed countries where infection is present is generally smaller than 1 case per 100,000 inhabitants, in endemic areas, such as some Arab countries, reports reach up to 200 cases per 100,000 inhabitants. However, because of the deficiencies in health services of many countries where brucellosis is endemic, there are no reliable data on the global status of the human disease .This is one of the reasons why exact impact of human brucellosis at the interface is not known. At present, there is no fully reliable method of preventing human brucellosis. To safeguard people, attention has been directed toward effectively controlling the disease in animals especially at wildlife/livestock/human interface. Sheep and goats are the main reservoirs of infection for humans; in some countries, bovines, buffalos, yaks (
5. Preventions and control of brucellosis at the interface
The control of brucellosis shared with wildlife requires the development of strategies that will reduce pathogen transmission between wildlife, both domestic animals and human beings.
In order to improve and succeed, governments need to improve on the quality of the national veterinary services and administrative organizations involved. The prevention and control of brucellosis in sub-Saharan Africa is hampered by low veterinary coverage and use of outdated diagnostic techniques . Furthermore, clinical diagnosis is complicated by variable incubation periods. Testing of livestock is cumbersome when dealing with farms located in remote areas or with animals from nomadic populations and migratory farmers. The identification of genus, species of field isolates, and molecular epidemiology of strains will benefit brucellosis eradication programs  since correct vaccination and control management will be possible. Many countries have implemented eradication programs resulting in the reduction or elimination of the disease, but the disease remains enzootic in many regions of the world. In those countries where the disease has been eradicated or strictly controlled, continued surveillance is essential to preventing the reemergence of the disease. Microbial genome typing or DNA fingerprinting is important for the delineation of outbreaks of infectious diseases and for the universal tracing of virulent or multi resistant pathogens . It is now of paramount importance to determine by epidemiological trace-back analysis where the infection originated, how it was spread, and what measures are needed to prevent additional spread of the disease from this primary source. The information will be vital at the interface since it will confirm the source of pathogen; hence, control and prevention efforts will be targeted at source. Knowledge of the spread and prevalence of the infection is essential when planning control measures.
It is generally recognized that the prevention of human brucellosis is best achieved by the control or eradication of the disease in animals, but this strategy is not relevant for protection against a bioterrorist attack on military or civilian populations. A human vaccine could possibly be an effective countermeasure for prevention of naturally occurring or deliberately induced human infections . Currently, three vaccine strains (
The control of brucellosis at wildlife/livestock/human interface requires improved collaboration between public health and veterinary services; this can be enhanced through the reinforcement or the establishment of national zoonoses committees, in which the relevant producer and consumer organizations should be also represented. As long as the national veterinary service organization is adequate, the prevalence of disease and economic resources will dictate the approach. Test- and slaughter-based programs are often unfeasible in developing countries because of the economic cost. In addition, countries that have successfully eradicated
Successful disease control may be dependent on accurate detection in wildlife reservoirs, including African buffalo (
This work has been possible thanks to progressive collaboration between Chinhoyi University of Technology and other technical institutions, particularly the Department of Livestock production and Veterinary services, Zimbabwe and CIRAD Zimbabwe.
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