Studies on Malayan filariasis in Bengkulu (Sumatera), Indonesia with special reference to vector confirmation

In an endemic focus of Brugia malayi in Bengkulu, Indonesia the microfilariae rate was 25%. The microfilariae showed nocturnal periodicity. Domestic cats in the same area were found to harbour B. pahangi, with a microfilariae rate of 23%. In the study area, the most prevalent man-biting Mansonia mosquitoes were Mn.bonneae (41%), followed by Mn.annulata (27%), Mn.uniformis (25%) and Mn.dives (7%). More Mansonia mosquitoes were collected outdoors than indoors between 1800-2200 hours. Natural infections with infective larvae of Brugia spp. were found in Mn.bonneae, Mn.dives, Mn.uniformis, Mn.annulata, and An.nigerrimus. Experimental infection studies revealed that Mn.annulata, Mn.bonneae, Mn.uniformis, An.nigerrimus and An.peditaeniatus permit the development of infective larvae. Under experimental condition, the vectorial competence is high in Mn.bonneae, intermediate in Mn.uniformis and low in An.hyrcanus group. It is concluded that the principal vectors of periodic B.malayi in the study area in Bengkulu are four Mansonia species (Mn.annulata, Mn.bonneae, Mn.uniformis and Mn.dives), and that the potential vectors include two Anopheles species (An.nigerrimus and An.peditaeniatus). This is the first record of Mn.bonneae being a vector of periodic B.malayi in Indonesia.