Summary
Brucellosis is one of the most important zoonoses that affects human welfare and livestock health worldwide. The significance of the disease is due to (a) the zoonotic impact on people in contact with infected animals, or consuming infected dairy products and (b) the economic impact caused by livestock disease and reproductive losses. Human brucellosis is a highly debilitating infection that is transmitted from animals and characterised by fever, anorexia, fatigue, headaches, depression and weight loss, clinical signs that may be confused with malaria or typhoid. Thus, brucellosis is a particular diagnostic problem in areas such as rural villages, where diagnostic services are non-existent or inadequate. The non-specific clinical picture is often misleading, with the result that inappropriate treatment is often given, prolonging the course of the disease and causing unnecessary expenditure of family income. Furthermore, even with the appropriate six week course of antibiotic therapy, relapses can often occur, resulting in chronic inability to work and economic hardship for families of earners.
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| Primary Relevance |
Low - High |
| Feeding and Nutrition |
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| Animal Health |
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| Commodities and Markets |
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| Other Husbandry |
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| Policy Relevance |
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To date, no large-scale studies have been carried out to investigate the problem of brucellosis in humans in Tanzania, and awareness of the disease amongst people, including medical graduates, is poor. In areas such as Usangu plains in the Southern Highlands of Tanzania, a febrile condition of humans that is unresponsive to anti-malarials is referred to as "Usangu fever". It is probable that the syndrome is brucellosis. Elsewhere, human brucellosis appears to be a growing concern in the Arusha Region, with 260 cases diagnosed in two districts during the past year alone. However, throughout the developing world, the true incidence of disease is considered likely to be at least 10 to 25 times higher than that reported. In East Africa, estimation of the true incidence in humans is also constrained by lack of a validated serological test, particularly in rural areas. For example, in both Tanzania and Kenya, there has generally been a poor agreement between results of diagnostic serological tests carried out in rural dispensaries and at veterinary research laboratories.
In addition to its significance as a direct cause of human disease, brucellosis in livestock is of considerable concern to the sustainable economy and food security of farming communities in Tanzania. In cattle and small ruminants, brucellosis causes severe economic losses as a result of abortion, sterility and reduced milk production. Infection in cattle is widespread throughout Tanzania, with seroprevalences of between 4.3% and 15.8% recorded in a range of intensive management systems. On some problem farms, seroprevalences exceeding 90% have been reported in association with severe abortion storms. Little information is currently available for more extensive farming systems where more than 97% of Tanzania's livestock are kept. Little is also known about brucellosis in sheep and goats, which are considered a major source of infection for people.
The role of wildlife in the epidemiology of brucellosis in Tanzania also warrants attention, given the fact that Brucella seropositives have been detected in 41/103 (39.8%) buffalo sampled in the Arusha region, an area where livestock-wildlife interactions are common. In other parts of the world, wild ungulates have been identified as important sources of infection for livestock. However, little is known about the dynamics of infection in livestock-wildlife systems in Africa.
The nature and magnitude of the zoonotic risk of brucellosis is likely to differ between pastoralist and smallholder systems, due to differences in management practices, contact with animals and consumption of animal products. There is, therefore, a need to quantify the relative importance of different factors in different husbandry and consumer systems in Tanzania, in order to target public health control measures most appropriately, to allow assessment of the impact of brucellosis on reproductive performance of animals, and to assist in development of cost-effective and appropriate disease control strategies. |
