Usage pattern, physical integrity & insecticidal efficacy of long-lasting insecticidal nets in Odisha State, India

BACKGROUND & OBJECTIVES: One of the major strategies being pursued for malaria control by the National Vector Borne Disease Control Programme is the distribution of long lasting insecticidal nets (LLINs) in endemic areas since 2009. Information on durability of insecticidal efficacy and physical integrity of LLINs and community usage at different time intervals of their use is essential to plan net replacements to maintain universal coverage for an effective and sustainable malaria control strategy. Therefore, a study was undertaken to assess these parameters in two malaria endemic districts of the Odisha State. METHODS: A total of 309 households were selected in 15 villages of two community health centres (CHCs) (Borigumma and Laxmipur) from Koraput district and one (Khairput) from Malkangiri district. Data on net usage were collected during March to July 2014 using semi-structured questionnaires. PermaNet 2.0 were sampled from all households, replaced with new ones, and bioassays were carried out to determine the insecticidal efficacy of LLINs after four and half, four and two years of field use following the standard procedure of World Health Organization. RESULTS: LLIN use rate varied from 57.9 to 90.2 per cent in the study CHCs. The annual washing rate per net in Borigumma, Khairput and Laxmipur was 6.6, 3.2 and 4.8, respectively. The LLINs used two years in the field caused 100 per cent mortality and four to four and half years caused below 80 per cent mortality, except one net. INTERPRETATION & CONCLUSIONS: Nearly 20 per cent of the people were out of net coverage and hence the Programme to ensure 100 per cent coverage. The community should adequately be educated so as to increase the net use rate and avoid incorrect washing practices.