Molecular detection of filarial parasites in black flies (Diptera: Simuliidae) in Laos

Filarial parasites cause diseases in humans and other animals and are transmitted primarily by hematophagous Diptera, including black flies (Simuliidae). However, knowledge of the vectorial role of black flies in transmitting filarial parasites in tropical Asia is limited. We used molecular approaches to detect filarial parasites in two common black flies, Simulium asakoae and S. khelangense, in Laos. Among 483 black flies, 15 were infected with filarial parasites. Based on sequence similarity analyses of the COI and 12S rDNA genes, the parasites were closely related to two filarial taxa: one previously reported from the same black fly species in Thailand and another recorded from domestic chickens. Phylogenetic analyses further revealed that the filarial parasites detected in S. asakoae and S. khelangense are closely related to genera of avian filarial parasites. The results are consistent with the biting habits of these species of black flies, which feed predominantly on chickens.