Empirical analysis suggests continuous and homogeneous circulation of Newcastle disease virus in a wide range of wild bird species in Africa.

Newcastle disease (ND) is one of the most important poultry diseases worldwide and can lead to annual losses of up to 80% of backyard chickens in Africa. All bird species are considered susceptible to ND virus (NDV) infection but little is known about the role that wild birds play in the epidemiology of the virus. We present a long-term monitoring of 9000 wild birds in four African countries. Overall, 3·06% of the birds were PCR-positive for NDV infection, with prevalence ranging from 0% to 10% depending on the season, the site and the species considered. Our study shows that ND is circulating continuously and homogeneously in a large range of wild bird species. Several genotypes of NDV circulate concurrently in different species and are phylogenetically closely related to strains circulating in local domestic poultry, suggesting that wild birds may play several roles in the epidemiology of different NDV strains in Africa. We recommend that any strategic plan aiming at controlling ND in Africa should take into account the potential role of the local wild bird community in the transmission of the disease.

Understanding the ecological drivers of avian influenza virus infection in wildfowl: a continental-scale study across Africa.

Despite considerable effort for surveillance of wild birds for avian influenza viruses (AIVs), empirical investigations of ecological drivers of AIV prevalence in wild birds are still scarce. Here we used a continental-scale dataset, collected in tropical wetlands of 15 African countries, to test the relative roles of a range of ecological factors on patterns of AIV prevalence in wildfowl. Seasonal and geographical variations in prevalence were positively related to the local density of the wildfowl community and to the wintering period of Eurasian migratory birds in Africa. The predominant influence of wildfowl density with no influence of climatic conditions suggests, in contrast to temperate regions, a predominant role for inter-individual transmission rather than transmission via long-lived virus persisting in the environment. Higher prevalences were found in Anas species than in non-Anas species even when we account for differences in their foraging behaviour (primarily dabbling or not) or their geographical origin (Eurasian or Afro-tropical), suggesting the existence of intrinsic differences between wildfowl taxonomic groups in receptivity to infection. Birds were found infected as often in oropharyngeal as in cloacal samples, but rarely for both types of sample concurrently, indicating that both respiratory and digestive tracts may be important for AIV replication.

Incidence of and beliefs about trypanosomiasis in the Senegal River Basin.

A survey was conducted for trypanosomiasis of 10,875 persons living in 56 villages in the Senegal River Basin in Mali. The incidence of the disease was found to be 137.9/100,000. An interview survey was simultaneously undertaken in order to elucidate local beliefs about the disease. Although trypanosomiasis is recognized as a distinct disease entity once the late stage has developed, there is no knowledge of its relationship to tsetse flies. It is common knowledge that hunters who frequent riverine forest galleries and forested savanna often contract the disease. Their frequent and intense exposure to Glossina sp. is not viewed as having any relationship to their contracting the disease.

The prevalence of diabetes mellitus in three population groups in the Republic of Mali.

Three different adult population groups in Mali were screened for diabetes mellitus by means of a post-prandial blood glucose determination. The prevalence of diabetes for the entire population sampled was found to be 1-4%. Diabetes mellitus was strongly suspected in an additional 8-4%. The prevalence of elevated post-prandial blood glucose levels was found to be the lowest (5-1%) among a group of Bambara farmers who live an active rural life and whose total daily caloric intake is less than 1,000 on the average, only half of it provided by carbohydrates.

Leishmanin skin sensitivity in the inland delta of the Niger.

Leishmanin skin tests were applied to 266 subjects in the city of Mopti which is located on several islands in the center of the inland delta of the Niger in the Republic of Mali. The antigen employed contains 6-10 million killed leptomonads per ml in a sterile suspension preserved with 1:10,000 thiomersal and unlike the phenol suspended antigens, does not give false positive tests. Of the 249 subjects who completed the study 12 (4.8%) had positive reactions, the lowest positive reaction rate yet observed in Mali. No false positive reactions occurred among 139 subjects tested with a control solution of 1:10,000 thiomersal. The absence of known cases of cutaneous leishmaniasis in Mopti's permanent population and the absence of suitable vectors within the city would indicate that positive reactors reflect previous L. tropica infections acquired in the surrounding rural areas where the disease is known to exist or else previous infection with non-pathogenic mammalian or reptilian species of Leishmania.