River geomorphologic features along a 165-km stretch of the Luangwa River in eastern Zambia were assessed in 2008 to determine their influence on hippopotamus pattern of density distribution. A fixed high wing Cessna 206 aircraft fitted with geographical positioning system (GPS) was flown over the stretch taking coordinates for each geomorphologic feature, followed by taking length in metres of each geomorphologic feature on the ground. A total hippopotamus count was later carried out along the same stretch. Sixty-four geomorphologic features were recorded along the stretch of the river. Of the total geomorphologic features recorded, 34 (53%) were river bends, 13 (20%) lagoons and 17 (27%) were confluences. Hippo density was highest in river bends (75.48%), confluences (9.18%), lagoons 6.03% and all the other features put together had only 9.38%. It was concluded that geomorphologic features influenced hippopotamus pattern of density distribution in the Luangwa River.

Although the quest to clarify the role of wild birds in the spread of the highly pathogenic H5N1 avian influenza virus (AIV) has yielded considerable data on AIVs in wild birds worldwide, information regarding the ecology and epidemiology of AIVs in African wild birds is still very limited. During AIV surveillance in Zambia (2008-2009), 12 viruses of distinct subtypes (H3N8, H4N6, H6N2, H9N1 and H11N9) were isolated from wild waterfowl. Phylogenetic analyses demonstrated that all the isolates were of the Eurasian lineage. Whilst some genes were closely related to those of AIVs isolated from wild and domestic birds in South Africa, intimating possible AIV exchange between wild birds and poultry in southern Africa, some gene segments were closely related to those of AIVs isolated in Europe and Asia, thus confirming the interregional AIV gene flow among these continents. Analysis of the deduced amino acid sequences of internal proteins revealed that several isolates harboured particular residues predominantly observed in human influenza viruses. Interestingly, the isolates with human-associated residues exhibited higher levels of virus replication in the lungs of infected mice and caused more morbidity as measured by weight loss than an isolate lacking such residues. This study stresses the need for continued monitoring of AIVs in wild and domestic birds in southern Africa to gain a better understanding of the emergence of strains with the potential to infect mammals. The GenBank/EMBL/DDBJ accession numbers for the sequences reported in this study are AB569476-AB569571.

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