Epidemiology and Determinants of Malaria Infection among Thai and Migrants in Health Region 1

Abstract

Malaria remains a significant public health issue in Thailand. This study aimed to investigate the epidemiology and factors associated with malaria infection among Thais and migrants in Health Region 1 between 2020 and 2024. Secondary data were obtained from the Malaria online system of the Department of Disease Control, comprising 5,747 confirmed cases. Descriptive statistics and chi-square tests (p < 0.05) were used for analysis. The results indicated that migrants outnumbered Thai patients by approximately 1.4 times. Among Thai patients, males were about 2.5 times more than females, with most aged 25 - 44 years. Among migrants, males were approximately 1.9 times more than females, and most were aged 15 - 24 years. Notably, 96.7% of migrants were of Myanmar nationality. The majority of Thai patients had agricultural careers (19.7%), while most migrant patients were laborers (48.6%). The highest number of cases was reported in Mae Hong Son province. Plasmodium vivax was the most frequently detected species, with peak transmission observed during the rainy season (June - August). Most Thai patients were infected within their residential villages (36.7%), whereas a large proportion of migrants (47.1%) acquired imported cases. In terms of risk-taking behavior, Thai patients were more likely than migrants to sleep under mosquito nets and use mosquito repellent. Statistical analysis revealed that sex, age, history of overnight travel before fever onset, occupation, source of infection, bed net belongings, sleeping under a net, use of mosquito repellent, indoor residual spray in both the patient’s home and areas with high transmission risk, active case detection by blood smear, effective treatment, and follow-up on the commitments were significantly associated with malaria infection. Findings from this study offered important guidance for planning and implementing more targeted areas and robust surveillance systems. With Thailand’s national malaria elimination goals.