African swine fever (ASF) a lethal, viral hemorrhagic disease of
domestic pigs, first reported from East Africa in 1921, is still widespread in this
region. In order to assess field heterogeneity at the regional level, nucleotide
sequences corresponding to the C-terminal end of the p72 gene were determined
for 77 ASF viruses of diverse temporal and species origin occurring in eight
East African countries. The number of sites completely conserved across all East
African sequences characterized in this study was 84.2% and 86.8% on nucleotide
and amino acid level, respectively. Phylogenetic analysis of a homologous 404 bp
region revealed the presence of thirteen East African genotypes, of which eight
appear to be country specific. An East African, pig-associated, homogeneous
virus lineage linked to outbreaks in Mozambique, Zambia and Malawi over a 23
year period was demonstrated. In addition, genotype I (ESACWA) viruses were
identified in East African sylvatic hosts for the first time which is significant as this
genotype was previously thought to be restricted to theWest African region where
it occurs only in domestic pigs. The presence of discrete epidemiological cycles
in East Africa and recovery of multiple genotypes affirms the epidemiological
complexity of ASF in this region.