Brucellosis as an Emerging Threat in Developing Economies:Lessons from Nigeria

Nigeria is the most populous country in Africa, has a large proportion of the world's poor livestock keepers, and is a hotspot for neglected zoonoses. A review of the 127 accessible publications on brucellosis in Nigeria reveals only scant and fragmented evidence on its spatial and temporal distribution in different epidemiological contexts. The few bacteriological studies conducted demonstrate the existence of Brucella abortus in cattle and sheep, but evidence for B. melitensis in small ruminants is dated and unclear. The bulk of the evidence consists of seroprevalence studies, but test standardization and validation are not always adequately described, and misinterpretations exist with regard to sensitivity and/or specificity and ability to identify the infecting Brucella species. Despite this, early studies suggest that although brucellosis was endemic in extensive nomadic systems, seroprevalence was low, and brucellosis was not perceived as a real burden; recent studies, however, may reflect a changing trend. Concerning human brucellosis, no studies have identified the Brucella species and most reports provide only serological evidence of contact with Brucella in the classical risk groups; some suggest brucellosis misdiagnoses as malaria or other febrile conditions. The investigation of a severe outbreak that occurred in the late 1970s describes the emergence of animal and human disease caused by the settling of previously nomadic populations during the Sahelian drought. There appears to be an increasing risk of re-emergence of brucellosis in sub-Saharan Africa, as a result of the co-existence of pastoralist movements and the increase of intensive management resulting from growing urbanization and food demand. Highly contagious zoonoses like brucellosis pose a threat with far-reaching social and political consequences

Proposals for the Rational Control and Prevention of Bovine Brucellosis in Nigeria

In an earlier presentation and in relevant publications (Esuruoso, 1972; 1974), it was shown that Nigeria could be divided into free, moderately infected and heavily infected areas with regard to bovine brucellosis. In this paper, it is recommended that where there is little or no infection at the moment the disease could be prevented by annual serological and bacteriological surveillance and removal by culling of any positive reactors. In moderately infected areas the few reactors should be identified by branding after the appropriate tests have been performed. They should then be separated from clean animals and allowed to complete their reproductive life without contact with clean herds. Offsprings of the infected cattle which later turn out to be clean after necessary testing before they reach the breeding age, could then be mixed with the clean herd.Heifer calves in heavily infected herds should be inoculated with Brucella abortus strain 19 (S19) attenuated vaccine at the age of 3 to 6 months. Cows and mature heifers in these herds should be tested annually and separated into clean and infected groups. The infected group should be kept on separate pastures from the clean group. They should also be confined for calving and their manger beddings should be destroyed by incineration.At slaughter as well as during abortions and infective calvings, the Brucella abortus serotypes causing the disease should be isolated, identified completely and propagated for further study and vaccine production. Under no circumstance should indiscriminate vaccination be carried out on any herd in this country, as this will confuse the situation and confound any rational attempts at control or eradication