The seroprevalence of Rift Valley fever (RVF), brucellosis, and Q fever among domestic ruminants on the southeastern shore of Lake Chad was studied. The study area consisted of two parts, including mainland and islands. On the mainland, the study was conducted in nine randomly selected villages and camps. On the islands, samples were collected from all four available sites. A total of 985 serum samples were collected and 924 were analyzed using enzyme-linked immunosorbent assay (ELISA) for RVF. A total of 561 samples collected from islands were analyzed using ELISA for Q fever and both ELISA and Rose Bengal tests (RBT) for brucellosis. The apparent RVF seroprevalence by species was 37.8% (95% confidence interval [CI] 34.2-41.3) in cattle, 18.8% (95% CI 12.3-25.2) in goats, and 10.8% (95% CI 3.0-18.5) in sheep. For brucellosis and Q fever, only cattle samples from islands were analyzed. For Q fever, the apparent seroprevalence was 7.8% (95% CI 5.6-10.1). For brucellosis, the RBT showed a prevalence of 5.7% (95% CI 3.8-7.6), and ELISA showed 11.9% (95% CI 9.3-14.6) with a kappa value of 0.53 showing a moderate agreement between the two tests. This study confirms the presence of the three diseases in the study area. More research is required to assess the importance for public health and conservation of the Kouri cattle breed.

BackgroundFasciolosis has been described in sub-Saharan Africa in many accounts, but the latest reports from Chad are from the 1970s. Mobile pastoralists perceive liver parasites as a significant problem and think that proximity to Lake Chad can lead to infection. This study aimed to assess the importance of liver fluke infections in mobile pastoralists’ livestock in the south-eastern Lake Chad region.In 2011, all animals presented at three slaughter slabs near Gredaya in the south-eastern Lake Chad area were examined for infection with Fasciola spp. during routine meat inspections.ResultsThis study included 616 goats, 132 sheep and 130 cattle. The prevalence of adult Fasciola gigantica was 68% (CI 60-76%) in cattle, 12% (CI 10-16%) in goats and 23% (CI 16-30%) in sheep. From all infected animals (n = 200), 53% (n = 106) were classified as lightly infected with 1-10 parasites, 18% (n =36) as moderately infected with 11-100 parasites and 29% (n = 58) as heavily infected with more than 100 parasites per animal.Animals grazing close to the shores of Lake Chad had a much higher risk of infection (prevalence =38%; n = 329) than animals not feeding at the lake (n = 353), with only one goat being positive (prevalence = 0.28%).The ethnic group of the owner was a strong determinant for the risk of infection. Ethnic group likely served as a proxy for husbandry practices. Geospatial distribution showed that animals originating from areas close to the lake were more likely to be infected with F. gigantica than those from more distant areas.ConclusionsLivestock belonging to ethnic groups which traditionally stay near surface water, and which were reported to feed near Lake Chad, have a high risk of infection with F. gigantica. Pastoralist perception of fasciolosis as a priority health problem was confirmed.Regular preventive and post-exposure treatment is recommended for animals grazing near the lake. However, further economic analysis is needed.