Hybridization between Brugia malayi and Brugia pahangi from south Kalimantan, Indonesia.

Hybridization experiments were carried out between sub-periodic Brugia malayi and B. pahangi recovered from cats originating from the same area in South Kalimantan (Borneo), Indonesia. Five to six week-old immature males and females of both species from Mongolian gerbil (Meriones unguiculatus) intraperitoneal infections were inoculated into the peritoneal cavity of other gerbils. Mating occurred between the species and microfilariae developed into infective third-stage larvae in mosquitoes. Larvae from the mosquitoes developed into adults in the peritoneal cavity of gerbils but microfilariae were not produced since the males were sterile. Back-crossing between hybrids and males and females of the parental species were also done and female hybrids produced microfilariae when crossed with parental males but females from the parental species did not produce microfilariae when mated with the hybrid males. This confirmed that the males were sterile but the females were not. If these species are hybridized in nature and humans are exposed to hybrid third-stage larvae, could this lead to occult filarial infection? These results confirmed previous hybridization experiments of these species orginating from other geographic areas.