Crowding at Lake Chad

Abstract

Background Mobile pastoralists in the Sahel zone interact very closely with their environment. The amount of rainfall affects their movements by determining pasture productivity. Parasites in the water threaten the health of the population and livestock as well as household economy which depends on milk sales and crop harvest. Although mobile pastoralists are an important economic factor for their country, little is known about their human and animal population and demography. Aims To better describe the population of mobile pastoralists and their livestock in south-eastern Lake Chad area. To test a mobile demographic surveillance system for people and their animals. To assess the prevalence of Fasciola gigantica. Methods Regular phone interviews about the human and animal population were conducted with a cohort of 20 mobile pastoralist camps and their travel routes recorded. The density of people and animals was assessed four times using random coordinates to define sampling areas Three slaughterslabs were observed for one year and all slaughtered animals examined for infection with F. gigantica. Results The mobile demographic surveillance proved to be feasible, low-cost and provided reliable real-time data. Furthermore the compliance was very high. The density of animals during the dry season exceeds up to 5 times the carrying capacities estimated for similar areas. Animals which were pastured in close proximity to the Lake Chad had a much greater risk of infection with F. gigantica. Only one animal who had not fed at the lake was infected. Geospatial analysis showed a clear pattern of higher prevalences closer to lake water. Conclusions A scaling up to a full scale mobile surveillance system is feasible and beneficial. The high animal density and access to natural resources have to be addressed on an institutional and government level, taking into account the needs of the mobile population. Livestock pastured close to Lake Chad has a great risk of infection with F. gigantica.