Retention and efficacy of long-lasting insecticide-treated nets distributed in eastern Sudan: a two-step community-based study

Background: In order to assess the effectiveness of long-lasting insecticide-treated nets (LLINs) as a method for malaria control, there is a need to determine how high is the retention of bed nets, how they are utilized, and how efficacious they are against the mosquitoes that transmit the disease. This is especially important in case of Sudan after emergence of resistance to pyrethroids in use. Methods: This two-step study aimed to assess the retention and efficacy of LLINs (Olyset (TM)) distributed in the year 2006 in Kassala district in eastern Sudan. In the first step, using a cluster sample technique, heads of 210 households (30 by 7) were interviewed, and six LLINs were collected and later tested for efficacy. In the second step, eight focus group discussion sessions were conducted to complement the results from the first step. Results: Results showed that the retention of LLINs was 92.9% one-and-half years after distribution. Some bed nets were distributed against a price. Utilization of bed nets by children under five years of age and by pregnant women was found to be 55% and 42.1% respectively. For the bioassay efficacy tests, mean knock down after 60 minutes was 91.1%, while mortality after 24 hours was 99.4%. Conclusion: LLINs (Olyset (TM)) were efficacious at the time of the study. People appreciated the usefulness but were not fully aware of their importance and were not motivated enough to use them. The retention of the bed nets was quite high but the utilization of the nets needs more focus from the National Malaria Control Programme. Bed net distribution activities should be accompanied by wide health education campaigns and followed up with tracking surveys to evaluate their effectiveness.