Imported Malaria Outbreak in Military Personnel Returning from Peacekeeping Operation in South Sudan - Thailand, 2023.

Malaria remains a global health concern, with Thailand primarily experiencing cases in border areas and from imported infections. During the third rotation of Thai peacekeeping troops returning from South Sudan between June and November 2023, a malaria outbreak was reported. In response to the outbreak, we conducted a retrospective cohort study, in which we identified 46 confirmed cases of malaria, with 27 occurring postdeployment. The most common species were Plasmodium falciparum (n = 19) and Plasmodium ovale (n = 16), with a median postdeployment time to first symptom of 14 weeks (interquartile range: 9-28). The analysis revealed that those relying on informal sources for malaria knowledge, such as friends, were at higher risk (hazard ratio: 4.92; 95% CI: 1.97-12.28). Challenges with prophylaxis adherence and glucose-6-phosphate dehydrogenase deficiency-related hemolysis were identified. This study calls for improved malaria prevention in South Sudan, better postdeployment monitoring, enhanced education for troops, and research on terminal prophylaxis to reduce cases.