Effect of indoor residual spraying on incidence of malaria in Kaoma District of Western Province, Zambia
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Introduction :Indoor residual spraying is one of the methods identified by World Health Organisation in combating malaria by controlling the vector mosquito. In line with the Zambian policy in malaria control, Kaoma district in Western Province of Zambia started implementing indoor residual spraying as the method of combating malaria in 2008. Aim :The main purpose of the study was to ascertain the effect of indoor residual spraying on incidence of malaria in Kaoma district of Western Province of Zambia. Specific objectives were to compare incidence of malaria in health centers with Indoor residual Spraying to health centers that did not implement indoor residual spraying, determine the relationship between management of indoor residual spraying programme and the outcome of malaria incidence and find out the community level of acceptance of IRS program in Kaoma district. Methodology :The study was a retrospective cohort analysis of incidence data across a single spray season, mixed with cross sectional survey results to assess levels of interventions, community understanding and perceptions and quality of IRS efforts. The study involved two stages. The first stage was retrospective audit of malaria incidence data across a single spray season. The second stage was cross sectional survey to assess levels of intervention, community understanding and perceptions, and quality of IRS efforts, which were compared with household sprayed. Interviews included household heads or the representative. The other party interviewed included the supervisors for the IRS program. Multistage sampling was used to select respondents from households and probability proportional to size (PPS) was used to select clusters in which respondents were picked. To validate the findings of the study, statistical significance was set at p < 0.05.Results.The study demonstrated that areas with a larger percentage of the population (greater than 60%) protected by Indoor residual spraying had lower incidence of malaria (82/1000 and 400/1000) compared to unsprayed area (398/1000 and 773/1000) both at the beginning and pick of malaria transmission season. A chi-square test shows that there was an association between spraying and reduced malaria incidence, p <0.05. Factors such as length of Insecticide Treated Nets ownership and building material for the house (p-value< 0.04 and 0.03) respectively had an association with the level of IRS acceptance. Acceptance of indoor residual spraying program was good at 64% of the 100% response rate interviewed. Reasons given for those who did not have the houses sprayed among others was absence from home (79%). There was an association between Knowledge of the use for IRS and school attendance p-value < 0.001. Management of the program was poor, negatively affecting results of indoor residual spraying, starting from ill timing (wrong season) to management of commodities such as personal protective equipments, Insecticide, inadequate transport and short notice given to the households. Conclusion :Indoor residual spraying was association with reduced malaria incidence in Kaoma district in areas where it was implemented. Poor management of the programme, however, negatively affected the results. The study clearly demonstrated that IRS activities continued during the rainy season. According to IRS policy activities of spraying should have been completed before the onset of rains. The district needs to focus on management of logistics, intensify sensitisation and improve on the starting time of IRS if it has to have the desired impact in preventing malaria. This matter should be critically looked at if Zambia has to eliminate malaria by 2015.