In 2018, Bhutan reported 54 cases of malaria, of which six were indigenous, 14 introduced and 34 imported. Considering the continuous reduction in the number of indigenous cases, Bhutan plans to eliminate malaria by 2025 under the Bhutan Malaria Elimination Strategy. The study was conducted to assess the presence of asymptomatic plasmodial infection in both, Bhutanese population living in malaria-risk areas and in migrant workers to guide the elimination strategies. A cross-sectional study was conducted from April to May 2016 in 750 Bhutanese people and 473 migrant workers. Plasmodium falciparum and Plasmodium vivax infections were investigated by using a rapid diagnostic test (RDT) and the polymerase chain reaction (PCR). Prevalence of asymptomatic plasmodial infection based on PCR was 0.27% (95% CI: 0.05–1.07%) among Bhutanese people with a mean age of 43 years old. The proportions of males and females were 45% and 55%, respectively. Among migrant workers, the prevalence of asymptomatic plasmodial infection was 0.42% (95% CI: 0.07–1.69%) with a mean age of 30 years old. The majority of migrant workers were from the neighboring Indian State of West Bengal (57.51%), followed by Assam (12.26%). RDT in both study groups did not detect any plasmodial infection. The presence of a low prevalence of asymptomatic plasmodial infection indicates that the current elimination strategies and interventions are effective.

Introduction: Bhutan is considered as a low endemic country for malaria. In the last decade, Bhutan has successfully reduced the number of malaria cases with the support from Global Fund and WHO. Sarpang, Samtse and Samdrup Jongkhar districts located in the Southern foothills of Bhutan records the most cases. Method: This retrospective study was undertaken with the available census record maintained in health centers of the three endemic districts and VDCP. Results: There were 892 confirmed malaria cases in 2009 and 41 cases in 2017 in three endemic districts. The slide positivity rate (SPR) declined from 2.2% in 2009 to 0.1% in 2017. The distribution of disease was significantly higher (p<0.05) amongst the male population with the increasing trend of Plasmodium vivax infection. The study found predominance of P. vivax in Samtse (93%), and Sarpang (62%) and Plasmodium falciparum in Samdrup Jongkhar (61%). The last four years (2014-2017) data showed that maximum cases detected were imported, followed by indigenous and introduced malaria; with 50%, 44% and 6%, respectively. The mortality and morbidity due to malaria has magnificently declined in the last decade. Conclusion: The large-scale implementation of vector control interventions, such as insecticide-treated bed nets, indoor residual spraying, free health care service and active vector surveillance has achieved a marked reduction in malaria incidence. Cross border malaria is still a huge challenge for elimination of malaria in Bhutan. Thus, imported malaria is an increasing problem due to high receptivity, and vulnerability.