The epidemiological situation of brucellosis in Africa

Brucellosis, as a geomedical literature survey has shown, is spread to a higher of lesser degree of incidence virtually over the whole African continent. Its epidemiological spectrum of host animals is especially rich amongst the domestic and wild animal species. All domestic animal species and 21 of 26 herbivorous and 5 of 12 carnivorous wild animal species screened yielded positive brucella antibody serotitres. Thus self-maintaining natural foci independent of the domestic stock have firmly been established. The mapping of the epidemiological situation must be based on survey data which should have been planned, exactly performed, analyzed and reported according to statistical rules. Unfortunately Africa is especially badly covered in the world literature in the field of brucellosis. Representing itself 32.0% (49/153) of the countries of the world, their Medical and Veterinary Departments contributed only 2.1% of the computerized world literature on brucellosis in the period 1969-74. This picture can be considerably changed by including the non-computerized "grey literature" of Department and Laboratory Annual Reports into the screening process. By introducing objective, mathematical criteria for determining the degree of incidence from the available data, the following results were obtained from the literature survey: brucellosis is known or suspected to exist in 40 of the 49 African countries (82%). In 20 (41%) of these countries it represents a major problem, in 10 (20.4%) a moderate problem in the other 10 countries a minor problem to human health and economy. Following the rule that brucellosis can be expected to exist everywhere in the world (with the exception of a few islands) where cattle, sheep and/or goats are kept unless it has been eliminated by vigourous measures of control, it may be expected that the remaining 9 African countries not yet reporting also harbour this chronic, zoonotic disease. 35 of the 40 countries reporting have found brucellosis regularly, 1 exceptionally among domestic animals, 5 among game animals. Only 17 of these 35 (48.5%) have scheduled the disease, even if its incidence has been reported to be high. Only 32 of the 49 countries report on human brucellosis. The main reservoirs of disease and risks of infection vary from place to place with the different main kinds of domestic stock, the animal husbandry and human consumption methods and habits. Thus mainly the cattle herds are the source of infection for those countries where large numbers of cattle are kept and the drinking of raw milk is the custom; however, there is no strict correlation between these two factors. Goats and sheep fill the epidemiological place in all those countries where the lack of marketable milk curtails its consumption; the small ruminants are kept as the main source of meat supply and in close contact with the farmers family within the compound or house.