Geographical risk mapping and molecular characterization of Burkholderia pseudomallei in human and soil in Bangladesh

<ns3:p> Background Melioidosis is a soil-borne bacterial disease, causing severe infection in human. The global estimated annual prevalence is 165,000, with South Asia considered a high-burden region for melioidosis. Bangladesh has documented over 100 human cases to date, with most infections occurring in agricultural workers, particularly those with diabetes. Rural populations are more vulnerable due to frequent exposure to soil. The ongoing hospital-based melioidosis surveillance detected 40 human cases from 20 districts. Human cases from wider geographical regions raised a significant concern about the environmental sources of <ns3:italic>Burkholderia pseudomallei.</ns3:italic> A previous study collected soil samples from four districts and detected <ns3:italic>B. pseudomallei</ns3:italic> in two samples of a district. We hypothesize that people living in rural areas across the country are equally vulnerable to <ns3:italic>B. pseudomallei</ns3:italic> and melioidosis remains underdiagnosed outside Dhaka, the capital city of Bangladesh. A country-wide study may provide an insightful understanding of the potential sources of <ns3:italic>B. pseudomallei.</ns3:italic> Methods This study proposes a cross-sectional approach to identify geographical hotspots for <ns3:italic>Burkholderia pseudomallei</ns3:italic> in soil. It will build upon the existing melioidosis surveillance system to select soil samples. Initially, samples will be collected from around the households of 43 confirmed human cases in 18 districts under current surveillance efforts. Additional samples will be collected from the remaining 46 districts. A total of 1068 soil samples will be collected from 64 districts. All soil samples will undergo testing through real-time PCR, and positive isolates from both soil and human cases will be further characterized using whole-genome sequencing. Antibiotic-resistant genes (ARGs) will also be detected using uniplex real time PCR and Sanger sequencing. Conclusions The findings of this study will raise awareness among public health officials and policymakers about transmission risks, informing targeted interventions in high-risk areas. </ns3:p>