While the goal of African pastoralists is health and longevity of herd and household, some of their management strategies appear to counter this long-term goal. Pastoralists in the far north region of Cameroon, for example, do not always remove chronically sick animals from their herds, even though chronic diseases, such as brucellosis, are contagious and have the potential to cause fertility problems in the herd. We used ethnographic and epidemiologic methods to understand why pastoralists do not remove chronically sick animals and whether their management strategies have an impact on herd fertility. We used semi-structured interviews to collect data on pastoralists' understandings of disease and its impacts on fertility as well as data on herd management. We compared these data with disease prevalence and herd fertility data to measure the effect of management strategies on herd fertility. We found that the percentage of chronically sick animals in a herd negatively correlated with herd fertility, but this was not true for the prevalence of brucellosis. Thus, preliminary examination of disease costs and benefits suggests that herders' decisions to keep sick animals in their herds may lower herd fertility, but this is not due to brucellosis alone. The results of this study underline the complexity of infectious disease ecology in pastoral systems and the need for holistic and comprehensive studies of the ecology of infectious diseases in pastoral systems.
Keywords: Brucellosis; Ecology of infectious diseases; Ethnoveterinary research; Livestock breeding strategies; Pastoral systems.