Testing the effectiveness of dengue vector control interventions

Abstract

Background: Community-based srategies to dengue vector control have been implemented in different countries worldwide, but there is a need for more evidence on their effectiveness. We present an application of a semiparametric mixed model to evaluate the results obtained through intersectoral coordination and community empowerment in one study carried out during six years in Playa Municipality, Cuba. Methods: A longitudinal comparing one intervention and one control area was conducted. The intervention encompasses two main stages separated by two dengue outbreaks. The first stage, focused on strengthening intersectoral coordination, was initiated in January 2000. In August 2003 a complementary strategy, focused on community empowerment was initiated in half of the intervention area. In the control area, routine dengue control activities continued without additional input. We used entomologic surveillance data from January 1999 to December 2005 to assess the effectiveness. We computed the Breteau indices (BI, number of positive container per 100 premises) per area and the 95% confidence interval for the difference between the BIs at each time point. A semiparametric mixed model to capture the evolution in time of Ae. Aegypti larval densities was fitted. Results: The Figure shows the fitted models for the differences in Ae. aegypti larvae densities between areas. The BIs in the control area had the lowest values before starting the intervention. This was reversed one year after the launch of the intersectoral activities for dengue control in the intervention area. In spite of spraying actions carried out during the intensive campaign that started in January 2002 in all areas, the differences in BIs between intervention and control areas remain significant until December 2002. Although for the next two years no differences were observed, they become significant again in December 2004, which corresponds with the implementation of the complementary community-based vector control strategy in the intervention area.

Conclusion: The model fitted allowed us to identified monotonous trends over time and reversal trends at particular moments. The confidence bands indicate sections with significantdifferences between areas. Our data augment the evidence that intersectoral coordination and community empowerment strategy to Ae. Aegypti control is effective.