Evaluating Space Time Cluster and Co-occurrence of Malaria Vectors of West Bengal in India

Abstract

Background Malaria, a prominent Vector Borne Diseases (VBDs) causing over a million annual deaths worldwide, predominantly affects vulnerable populations in the least developed regions. Despite their preventable and treatable nature, malaria remains a global public health concern. In the last decade, India has faced a significant decline in malaria morbidity and mortality. As India pledged to eliminate malaria by 2030, this study examined a decade of surveillance data to uncover space-time clustering and seasonal trends of Plasmodium vivax and falciparum malaria vectors in West Bengal. Methods Seasonal and Trend decomposition using Loess (STL) was applied to detect seasonal trend and anomaly of the time series. Univariate and multivariate space-time cluster analysis of both vectors was performed at block level using Kulldorff's space-time scan statistics from April 2011 to March 2021 to detect statistically significant space-time clusters. Results From the time series decomposition, a clear seasonal pattern is visible for both vectors. Statistical analysis indicated considerable high-risk P. vivax clusters, particularly in the northern, central, and lower Gangetic areas. Whereas, P. falciparum was concentrated in the western region with a significant recent transmission towards the lower Gangetic plan. From the multivariate space-time scan statistics, the co-occurrence of both vectors was detected with four significant clusters, which signifies the regions experiencing a greater burden of malaria vectors. Conclusions This non-random distribution underscores the urgency for dynamic monitoring and targeted interventions. Significant geographical and spatiotemporal heterogeneity was evident for both malaria vectors, emphasizing the need for tailored approaches. Identifying co-occurring clusters offers crucial insights into disease risk, paving the way for focused control initiatives. Addressing the drivers of malaria transmission in these diverse clusters demands regional cooperation and strategic strategies, crucial steps towards overcoming the final obstacles in malaria eradication.