Investigation of malaria outbreak in a Karen hill tribe community, Ban Rai District, Uthai Thani Province between April and May 2023

Abstract

Uthai Thani Provincial Health Office was alerted by Ban Rai Hospital regarding the detection of five confirmed cases of malaria among the Karen hill tribe community situated in Village Group No. 2, Kaen Makrut Subdistrict, Ban Rai District, Uthai Thani Province. These malaria cases were reported between April 14 and May 9, 2023. Subsequently, an outbreak investigation team was deployed to the affected area from May 10-12, 2023, to validate the diagnosis, characterize the epidemiological profile of the confirmed cases, identify potential sources and modes of disease transmission, and provide recommendations for disease prevention and control. The study employed a descriptive research design. During the investigation, the team meticulously scrutinized medical records and conducted an active case finding among 166 villagers in Village Group No. 2, utilizing a specialized case investigation form developed by Division of Epidemiology and Rapid Diagnostic Test (RDT) kit. Individuals testing positive via RDT underwent further examination using the thin/thick film method and among 166 villagers tested, 1 Plasmodium vivax case was detected. The investigation team confirmed a total of six cases of P. vivax malaria. The majority of affected individuals were male agricultural laborers with a history of travel between the village and neighboring provinces classified as malaria high-risk areas. The investigation team observed that communal living conditions within the community futher amplified the risk of infection. While the principal vector, i.e., Anopheles minimus mosquitoes and larvae were identified, Plasmodium spp. was not detected in the adult mosquitoes. It was observed that a significant proportion (98.19 %) of villagers relied on conventional mosquito nets for sleeping, with only one-fifth (21.08%) possessing awareness regarding the disease-causing potential of mosquitoes, and a minority (4.82%) utilizing mosquito repellents for personal protection. This circumstance significantly heightened the risk of potential future outbreaks. In light of these findings, the investigation team recommends continuous surveillance, intensifying awareness campaigns concerning the disease and advocating for self-protection measures, particularly in anticipation of the outbreak season. Moreover, the provision of resources for disease prevention and control, alongside the implementation of surveillance measures targeting individuals with a history of travel from high-risk areas, is strongly recommended.