Background Insecticide-treated nets have proven efficacy as a malaria-control tool in Africa. However, the transition from efficacy to effectiveness cannot be taken for granted. We assessed coverage and the effect on child survival of a largescale social marketing programme for insecticide-treated nets in two rural districts of southern Tanzania with high perennial malaria transmission.
Methods Socially marketed insecticide-treated nets were
introduced step-wise over a 2-year period from May, 1997, in
a population of 480 000 people. Cross-sectional coverage
surveys were done at baseline and after 1, 2, and 3 years. A
demographic surveillance system (DSS) was set up in an
area of 60 000 people to record population, births, and
deaths. Within the DSS area, the effect of insecticide-treated
nets on child survival was assessed by a case-control
approach. Cases were deaths in children aged between
1 month and 4 years. Four controls for each case were
chosen from the DSS database. Use of insecticide-treated
nets and potential confounding factors were assessed by
questionnaire. Individual effectiveness estimates from the
case-control study were combined with coverage to estimate
community effectiveness.
Findings Insecticide-treated net coverage of infants in the
DSS area rose from less than 10% at baseline to more than
50% 3 years later. Insecticide-treated nets were associated
with a 27% increase in survival in children aged 1 month to
4 years (95% CI 3–45). Coverage in such children was higher
in areas with longer access to the programme. The modest
average coverage achieved by 1999 in the two districts (18%
in children younger than 5 years) suggests that insecticidetreated
nets prevented 1 in 20 child deaths at that time.
Interpretation Social marketing of insecticide-treated nets
has great potential for