Seroprevalence of Burkholderia pseudomallei among international travelers.

OBJECTIVES

Melioidosis, caused by Burkholderia pseudomallei, is increasingly recognized as a travel-associated infection, yet the extent of exposure among international travelers remains unknown. We aimed to determine B. pseudomallei seroprevalence among travelers to Southeast Asia and explore risk factors.

METHODS

We conducted a cross-sectional study at the Hospital for Tropical Diseases, Bangkok, enrolling travelers aged ≥18 years from non-endemic regions who had spent ≥1 month in Southeast Asia. Sera were tested by indirect enzyme-linked immunosorbent assay using two B. pseudomallei antigens, hemolysin co-regulated protein 1 and O-polysaccharide. Predefined diagnostic and exposure serological thresholds were applied. Risk factors were assessed by logistic regression.

RESULTS

Between August 2025 and January 2026, 370 travelers were enrolled. Overall, 49 (13.2%) were seropositive, including 25 (6.8%) with probable melioidosis and 24 (6.5%) with probable environmental exposure. Independent risk factors were female sex (adjusted odds ratio [aOR] 1.96; 95% confidence interval 1.05-3.67), North American origin (aOR 2.73; 1.44-5.18), and underlying medical conditions (aOR 2.25; 1.14-4.41).

CONCLUSION

B. pseudomallei exposure among travelers to Southeast Asia is not rare, with one in eight seropositive. Inclusion of melioidosis in the differential diagnosis of febrile returning travelers, complemented by diagnostic approaches beyond culture alone, is needed to reduce misdiagnosis and preventable mortality.