Efficacy of factory-treated and dip-it-yourself long lasting insecticide-treated bednets against cutaneous leishmaniasis vectors in the sub-Andean region of Colombia: results after two years of use

BACKGROUND

Long lasting insecticide-treated nets (LLINs) may be effective for vector control of cutaneous leishmaniasis (CL). Their efficacy, however, has not been sufficiently evaluated.

OBJECTIVE

To evaluate the large-scale efficacy of LLINs on Lutzomyia longiflocosa entomological parameters up to two years post-intervention in the sub-Andean region of Colombia.

METHODS

A matched-triplet cluster-randomised study of 21 rural settlements, matched by pre-intervention L. longiflocosa indoor density was used to compare three interventions: dip it yourself (DIY) lambda-cyhalothrin LLIN, deltamethrin LLIN, and untreated nets (control). Sand fly indoor density, feeding success, and parity were recorded using CDC light trap collections at 1, 6, 12, and 24 months post-intervention.

FINDINGS

Both LLINs reduced significantly (74-76%) the indoor density and the proportion of fully engorged sand flies up to two years post-intervention without differences between them. Residual lethal effects of both LLINs and the use of all nets remained high throughout the two-year evaluation period.

CONCLUSIONS

Both LLINs demonstrated high efficacy against L. longiflocosa indoors. Therefore, the deployment of these LLINs could have a significant impact on the reduction of CL transmission in the sub-Andean region. The DIY lambda-cyhalothrin kit may be used to convert untreated nets to LLINs increasing coverage.

Key words:
sand flies; Lutzomyia; prevention and control; lambda-cyhalothrin; deltamethrin