Insecticide-treated bed nets in rural Bangladesh: their potential role in the visceral leishmaniasis elimination programme

Objective To analyse the feasibility, acceptability and effectiveness of insecticide-treated bed nets with slow-release insecticides (KO Tab 123) as an option for kala-azar vector management in Bangladesh.

Methods Intervention study involving an insecticide dipping programme through village health workers supervised by public health officers covering 6967 households in Mymensingh and 8287 in Rajshahi district. In a subsample of households, sandfly densities at baseline, 1, 12 and 18 months were measured with CDC light traps both in intervention and control areas. Bioassays were performed for determining the bioavailability of the insecticide and tests of chemical residues in the treated bed nets were undertaken. Satisfaction surveys and direct observation of use of treated bed net use were conducted.

Results The dipping programme was feasible with the help of communities and public health staff, was well accepted, reached a coverage of 98.2% and 96.2% in the two study sites within 4 weeks and was effective in terms of a significant reduction in sandfly densities (approximately 60%) for a period of 18 months. Bioassay results were satisfactory (>80% sandfly mortality) and the average chemical content of the treated bed nets was sufficient for killing sand flies at the end of the observation period.

Conclusion Bed nets treated with slow-release insecticides can be an important complementary measure for sandfly control in the visceral leishmaniasis elimination programme