Impact on malaria morbidity of a programme supplying insecticide treated nets in children aged under 2 years in Tanzania: community cross sectional study

Objective To assess the impact of a social marketing programme for distribu ting nets treated with insecticide on malarial parasitaemia and anaemia in very young children in an area of high malaria transmission. Design Community cross sectional study. Annual, cross sectional data were c ollected at the beginning of the social marketing campaign (1997) and the s ubsequent two years. Net ownership and other risk and confounding factors w ere assessed with a questionnaire. Blood samples were taken from the childr en to assess prevalence of parasitaemia and haemoglobin levels. Setting 18 villages in the Kilombero and Ulanga districts of southwestern T anzania. participants A random sample of children aged under 2 years. Main outcome measures The presence of any parasitaemia in the peripheral bl ood sample and the presence of anaemia (classified as a haemoglobin level o f <80 g/l). Results Ownership of nets increased rapidly (treated or not treated nets: f rom 58% to 83%; treated nets: from 10% to 61%). The mean haemoglobin level rose from 80 g/l to 89 g/l in the stud children in the successive surveys. Overall, the prevalence of anaemia in the stud population decreased from 49 % to 26% in the two years studied. Treated nets had a protective efficacy o f 62% (95% confidence interval 38% to 77%) on the prevalence of parasitaemi a and of 63% (27% to 82%) on anaemia. Conclusions These results show that nets treated with insecticide have a su bstantial impact on morbidity when distributed in a public health setting.