Community use of permethrin treated bed-nets: its impact on malaria vectors and malaria in children in north eastern Tanzania.

In coastal Tanzania malaria is generally perennial and seasonally intense. Experimental hut studies have determined that treated bednets reduced mosquito biting considerably. A malaria control trial was therefore launched in Muheza district in 1986. This paper describes the effects of permethrin-treated bednets upon malaria transmission when used by all inhabitants of four communities in the Muheza area of northern Tanzania. Permethrin is a safe insecticide which can be used at close contact with man without any adverse effect. It is easy to apply and can be done by the villagers themselves. Two of the communities have thus far received nets. After one year of use many nets were torn although the majority were still in good shape. The mean survival of mosquito vectors was markedly reduced by the introduction of nets in Mlingano and Mngaza probably the result of large numbers of mosquitos being killed through contact with the nets. Thus in the treated villages few mosquitos survived to the age at which they could develop malarial sporozoites. The data indicate a reduction in malaria-related morbidity. The authors point out that bednets are very expensive and rarely used in rural areas of Tanzania. Preliminary observations indicate that the less expensive sisal curtain treated with permethrin provides protection equal to that given by a torn treated net. It is also stressed that people must be taught the value of personal protection in malaria control