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Sleeping arrangements under long-lasting impregnated nets (LLIN) were recorded in 2467 households during the low malaria transmission season (May-June 2007) and the same families were followed up during the high malaria transmission season (December 2007-January 2008) in two malaria-endemic areas of Sri Lanka. Approximately 800 households each from the three main ethnic groups were studied. The number of families lost to follow-up was 68. A significant increase was seen in the proportion of households using LLINs the previous night during the high transmission season (96%) compared with the low transmission season (90%) (P< or =0.001 for all three ethnic groups). When sleeping arrangements of the entire population were considered, priority to sleep under the LLIN was given to children under 5 years during both seasons. The percentage of children under five who slept under a LLIN increased from 75% during the low transmission season to 90% during the high transmission season. Utilisation of LLINs by pregnant women was low; only approximately 45% of pregnant women reported sleeping under a LLIN during both seasons. The study suggests the possible need for re-focusing of health education messages regarding the importance of LLIN use among pregnant women.

The Anti Malaria Campaign distributed approximately 300,000 long-lasting impregnated nets (LLINs) to malaria-endemic areas in Sri Lanka during the years 2005 to 2007. We conducted a community-based cross-sectional survey among 2467 households distributed among the three major ethnic groups of Sri Lanka to study the perceptions and practices with regard to the use of LLINs in order to improve their use. In a majority of households the number of LLINs available was not sufficient for the number of people, although there was a small percentage of households that had excess nets. The information and advice given at the time of distribution regarding use of the nets differed amongst the three groups and was not consistent. Dissemination of this knowledge within the family was not observed. A relationship between knowledge regarding LLINs and reported practices on washing and drying of LLINs was found. It was noted that net shape may influence net use, with cone shaped nets being more popular. Efforts to increase knowledge on LLINs using behaviour change communication techniques would have more effectively contributed to achieve planned outcomes. Proper use of LLINs will undoubtedly contribute to further reduction of malaria in Sri Lanka.

The malaria situation in Sri Lanka worsened during the 1990s with the emergence and spread of resistance to the drugs and insecticides used for control. Chloroquine resistance has increased rapidly over this period, but adverse changes in malaria transmission are more closely associated with insecticide use rather than drug resistance. Insecticide susceptibility tests were routinely carried out in key anopheline vectors across the country for more than a decade. These sentinel data were combined with data collected by other research programmes and used to map the spatial and temporal trends of insecticide resistance in the main vectors, Anopheles culicifacies and A. subpictus, and to examine the relationship between insecticide resistance, changes in national spraying regimens and malaria prevalence. Both species had widespread resistance to malathion, the insecticide of choice in the early 1990s. Both species were initially susceptible to the organophosphate and pyrethroid insecticides used operationally from 1993, but some resistance has now been selected. The levels of malathion and fenitrothion resistance in A. subpictus were higher in some ecological regions than others, which may be related to the distribution of sibling species, agricultural pesticide exposure and/or environmental factors. The study highlights that the emergence and spread of insecticide resistance is a constant threat and that active surveillance systems are vital in identifying key vectors and evidence of resistance.