Anthropophily, zoophily and roles in onchocerciasis transmission of the Djodji form of Simulium sanctipauli and S. squamosum in a forest zone of Togo.

Adult female Simulium damnosum s.l. were caught at human and cattle bait at Djodji in Togo. Two members of the Simulium damnosum complex, the Djodji form of S. sanctipauli (74.9% of the total catch) and S. squamosum (25.1%), were identified and both were mainly anthropophilic. Although each species was also recorded feeding on cattle or turkey baits, most flies which were caught at animal baits did not take blood from them. Flies caught unfed at the cattle bait tended to be larger and have higher parous rates than those caught on man. S. sanctipauli flies were on average larger than S. squamosum but the sizes of both species varied seasonally. Infections with Onchocerca volvulus were found in both species. The infection rates varied seasonally with the highest levels occurring in the wet season. The Djodji form of S. sanctipauli is potentially a much more efficient vector (162 L3/1000 biting flies) than both S. squamosum (48 L3/1000 biting flies) and the S. sanctipauli s.l. found in the Cote d'Ivoire.