Evidence of populational Burkholderia pseudomallei exposure in Madagascar.

BACKGROUND: Burkholderia pseudomallei (Bp), the causative agent of melioidosis, poses a significant health risk in endemic regions. This study aimed to characterize six previously identified Bp antigens for exposure monitoring in potential endemic setting of Madagascar and to assess potential exposure and reactivity across Madagascar to inform diagnostic strategies and understand regional exposure patterns. METHODS: Six highly reactive Bp antigens, CPS I, LPS types A and B, HCP1, AhpC, and GroEL, were characterized using the protein BLAST (BLASTp) algorithm against the NCBI non-redundant protein database to evaluate conservation and specificity. Serological reactivity was analyzed in 5,736 serum samples from six regions of Madagascar using Luminex bead-based multiplex assays. Principal Component Analysis was conducted to identify co-reactivity patterns. Environmental sampling in Mahajanga assessed the presence of Bp DNA in soil and water samples via real-time PCR. RESULTS: Antigen conservation varied, with HCP1 and CPS I demonstrating the highest specificity, suggesting their potential for targeted serological detection. Seroprevalence and co-seroprevalence were highest in the Mahajanga region, particularly for HCP1 and CPS I (p < 0.0001). PCA revealed distinct antigen-specific immune response profiles. Environmental sampling confirmed the presence of Bp DNA in a water sample from Mahajanga, indicating local bacterial presence in the environment. CONCLUSIONS: These findings suggest human exposure to Bp occurs in multiple regions in Madagascar. HCP1 and CPS I emerged as promising targets for diagnostic applications, and environmental detection of Bp underscores the need for targeted public health interventions in higher-risk regions like Mahajanga.