The role of some cyclorrhaphan flies as carriers of human helminths in Malaysia

The role of some adult flies (Diptera: Cyclorrhapha) as carriers of helminth parasites of man was studied at four sites in Malaysia: a refuse dump, where no helminth-positive flies were detected, and in three peri-domestic situations where four species of flies carried up to three types of nematodes. The dominant fly species Chrysomya megacephala (Fabricius) carried eggs of the roundworm Ascaris lumbricoides L., the pinworm Trichuris trichiura (L.) and hookworm on the adult external body surface and in the gut lumen, in association with Bukit Lanjan aborigines. Chrysomya rufifacies (Macquart) and Sarcophaga spp. also had Ascaris lumbricoides and Trichurus trichiura eggs in their gut contents. Human helminths were not recovered from Lispe leucospila (Wiedemann), Lucilia cuprina (Wiedemann) or the housefly Musca domestica L. In an urban slum area of Kuala Lumpur city, filariform larvae identified as the hookworm Necator americanus (Stiles) occurred in the intestines of the face-fly Musca sorbens Wiedemann (22 larvae per 100 flies) and of Chrysomya megacephala (4.5 larvae per 100 flies). This concentration of apparently infective N. americanus in M. sorbens, a fly which often breeds in faeces and browses on human skin, could have transmission potential.