Field Trials of Pyrethroid Impregnated Bednets in Northern Tanzania—1. Effect on Malaria Transmission

Studies involved the evaluation of two types of pyrethroids and two controls in a single study village settlement. A total of 1277 bednets were distributed to 75 % of 420 houses in the village, in July 1989, 378 were treated with lambda cyhalothrin (Icon®), 411 with deltamethrin and 331 were untreated. A total of 336 people were not given any nets. Entomological evaluation showed that both pyrethroids have an excito-repellent and lethal effect on mosquito vector species. In assessment of malaria reduction in children as the target group, those sleeping in deltamethrin treated houses showed a greater reduction in parasite rate than those sleeping in lambda cyhalothrin nets: Overall reduction of malaria parasite rate of school children examined was 68 %. Biological efficacy in both pyrethroid treated nets persisted over a period of 6 months. Another added advantage was that the individual using the net was protected against mosquitoes and other pests such as cockroaches, fleas, lice and bedbugs. Incorporation of pyrethroid impregnated nets in malaria control programmes involving community participation is recommended.