Date of Award
Master of Science (MS)
David A. Larsen
Environment, Indoor Residual Spray, Malaria
Medicine and Health Sciences
Malaria transmission control in endemic areas is dependent on both individual
and community level protective measures. Indoor residual spray (IRS) campaigns work to reduce transmission of malaria illness by covering the walls of houses in areas at risk with an insecticide that kills mosquitoes landing there. The World Health Organization recommends IRS campaigns successfully spray at least 80% of structures to maximize impact of the campaigns against malaria vectors.
Programmatic data from the 2016 IRS campaign conducted in Luapula Province, Zambia was used to examine the spatial distribution of houses missed during spray campaigns. Additionally, Poisson regression methods examine various factors associated with increasing IRS coverage at the community levels. Spatial distribution was assessed through a difference in K-function analysis.
A difference in K-function analysis suggested clustering of missed houses at all spatial scales examined. Poisson regression analysis suggested that lower population density and fewer nighttime lights were negatively associated with spray teams’ ability to locate houses targeted for IRS implementation. Global Moran’s I analysis confirms high levels of spatial autocorrelation among missed houses.
These analyses indicate that the remoteness of structure location is a significant predictor of clusters of targeted structures being missed by spray teams during IRS campaigns. The impact that these missed clusters could have on the intended reduction of transmission control of malaria could be devastating for endemic areas, rendering many areas unprotected by IRS. Similar to issues of herd immunity, large gaps in coverage end up leaving all of the resources that are put into effective IRS program design and operations less effective if the minimum threshold is not met. Lack of threshold coverage may leave whole communities open to much higher levels of malaria transmission, and increased incidence of preventable malaria.
Mackowski, Madeline, "Factors Limiting Effective Coverage of Indoor Residual Spraying Campaigns in Luapula Province, Zambia" (2020). Theses - ALL. 400.