Background
Nepal is attempting to eliminate malaria by 2026. Despite decreased malaria burden in Nepal between 2004 and 2018, studies have shown that some malaria indicators are increasing in certain parts of the country and that malaria has shifted to previously non-endemic areas. The objective of this study is to analyze the spatio-temporal patterns of malaria in Nepal from 2005 to 2018, following the introduction of Long-Lasting Insecticidal Nets (LLINs) as vector control intervention.
Methods
Data describing five different malaria indicators were obtained from annual reports of the Department of Health Services of the Government of Nepal: incidence of Indigenous Malaria, Imported Malaria, PV ( Plasmodium vivax) Malaria, PF ( Plasmodium falciparum) Malaria, and Total Malaria. Spatial variation in temporal trend method was employed in SaTScan software to detect the unusually high or low temporal trends of malaria indicators, and to generate their spatio-temporal clusters.
Results
All five indicators revealed spatiotemporal clusters of increasing malaria. Indigenous Malaria increased by 113.71% in a cluster of three mountainous districts where malaria was previously non-endemic. Most clusters of Imported Malaria had an increasing trend. The most prominent cluster included Kathmandu, the capital, where Imported Malaria increased by 156.22%. PV and PF Malaria also had clusters with an increasing trend. There were two clusters of Total Malaria with an increasing trend. Even though some clusters had decreasing trends in malaria indicators, the rate of decrease incidence in the clusters was lower than that outside the clusters.
Conclusion
The overall malaria burden is decreasing in Nepal as the country progresses closer to the elimination deadline. However, several spatiotemporal clusters showed increasing trends of malaria incidence. Furthermore, in clusters where a decreasing incidence trend was observed, the rate of decrease was far lower than the rate outside the cluster. Thus, it is necessary to focus vector control interventions in all these clusters. This information can help public health officials to make decisions for implementing vector control interventions to successfully eliminate malaria form the country.