Can vector control play a useful supplementary role against bancroftian filariasis?

A single campaign of mass treatment for bancroftian filariasis with diethyl carbamazine (DEC) in Makunduchi, a town in Zanzibar, United Republic of Tan zania, combined with elimination of mosquito breeding in pit latrines with polystyrene beads was followed by a progressive decline over a 5-year perio d in the microfilarial rate from 49% to 3%. Evidence that vector control ha d contributed to this long-term decline was obtained by comparison with ano ther town, Moga, where a DEC campaign was used without vector control and w here resurgence of microfilariae could be observed 3-6 years after the camp aign. In Zanzibar town, treatment of 3844 wet pit latrines and cesspits wit h polystyrene beads reduced the adult mosquito population in houses by abou t 65%. Supplementary treatment of open drains and marshes with Bacillus sph aericus produced little or no additional reduction compared to a sector of the town where only pit treatment with polystyrene was carried out. The cos t and effort of achieving the 65% reduction in mosquito population could ha rdly be justified for its impact on filariasis alone, but its noticeable im pact on biting nuisance might help to gain community support for an integra ted programme.