Space–Time Clustering Characteristics of Malaria in Bhutan at the End Stages of Elimination

Abstract

Malaria in Bhutan has fallen significantly over the last decade. As Bhutan attempts to eliminate malaria in 2022, this study aimed to characterize the space–time clustering of malaria from 2010 to 2019. Malaria data were obtained from the Bhutan Vector-Borne Disease Control Program data repository. Spatial and space–time cluster analyses of Plasmodium falciparum and Plasmodium vivax cases were conducted at the sub-district level from 2010 to 2019 using Kulldorff’s space–time scan statistic. A total of 768 confirmed malaria cases, including 454 (59%) P. vivax cases, were reported in Bhutan during the study period. Significant temporal clusters of cases caused by both species were identified between April and September. The most likely spatial clusters were detected in the central part of Bhutan throughout the study period. The most likely space–time cluster was in Sarpang District and neighboring districts between January 2010 to June 2012 for cases of infection with both species. The most likely cluster for P. falciparum infection had a radius of 50.4 km and included 26 sub-districts with a relative risk (RR) of 32.7. The most likely cluster for P. vivax infection had a radius of 33.6 km with 11 sub-districts and RR of 27.7. Three secondary space–time clusters were detected in other parts of Bhutan. Spatial and space–time cluster analysis identified high-risk areas and periods for both P. vivax and P. falciparum malaria. Both malaria types showed significant spatial and spatiotemporal variations. Operational research to understand the drivers of residual transmission in hotspot sub-districts will help to overcome the final challenges of malaria elimination in Bhutan.

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

“…Despite the steep decrease in malaria incidence across India, there are few endemic pockets where malaria remains a signi cant public health challenge to pose a stiff challenge to India's malaria elimination efforts. In order to eliminate the parasite and prevent its recurrence, nding these nal pockets of transmission is essential (5). In the Indian state of West Bengal, malaria is predominantly transmitted by P. vivax and is also co-endemic with P. falciparum, considered the deadliest form of malaria, varied across due to different physiographic zones, political border (interstate and international) with highendemic malaria region.…”

Malaria Epidemiology Along the Indian Districts Bordering Bhutan and Implications for Malaria Elimination in the Region

“…3 The seven India-lining districts mentioned above are located in the foothills of southern Himalayan, bordering the Indian states of Assam and West Bengal. 4 Between 2000 and 2009, continuous decline in malaria morbidity (from 5,935 to 972 cases) and mortality (from 15 to 4) was reported in Bhutan. 3 Since 2009, Bhutan has decreased overall malaria incidence with cases below 1 per 1,000 population and thus the country is moving towards malaria elimination.…”

“…6 Bhutan's malaria control has been credited to the implementation of a multi-pronged approach that includes early diagnosis, prompt treatment, use of indoor residual spraying, longlasting insecticidal nets, and integrated vector management. 4 These measures have resulted in an interruption of indigenous transmission in 18 out of 20 districts. 4,5 The national framework for malaria elimination of India aims to eliminate malaria by 2030.…”

“…4 These measures have resulted in an interruption of indigenous transmission in 18 out of 20 districts. 4,5 The national framework for malaria elimination of India aims to eliminate malaria by 2030. 7 As of 2019, 7.5% (25K/338K) of the total malaria cases and 14.5% (23K/ 157K) of Plasmodium falciparum cases have been reported from the north-eastern states of India, namely Assam, Arunachal Pradesh, Manipur, Meghalaya, Mizoram, Nagaland, Sikkim and Tripura.…”

Distribution and Risk Factors of Malaria in the Greater Accra Region in Ghana

“…Therefore, targeted distribution of preventative measures is more likely to be effective as opposed to uniform black resource allocation [22]. Hotspot and cluster analyses are useful tools for assessing geographic variation in malaria risk and incidence [23][24][25][26]. Understanding the temporality of transmission can further support decisions regarding the timing of control measure deployment.…”