Seroepidemiology of melioidosis and its associated risk factors of rural horses in Bangladesh.

Background: The disease melioidosis was named by Stanton and Fletcher in 1932 from the Greek ‘melis’ (distemper of asses) and ‘eidos’ (resemble). During the last century, this Gram-negative environmental bacterium has been variously known as Bacillus pseudomallei, Bacillus whitmorii, Malleomyces pseudomallei, Pseudomonas pseudomallei, and, since 1992, Burkholderia pseudomallei. In the latter half of the 20th century, melioidosis emerged as a significant public health concern in Southeast Asia and northern Australia. Severe melioidosis is associated with a case fatality rate of 50% in Thailand and 20% in Australia among all patients. Melioidosis affects both humans and animals elsewhere but is only reported in humans in Bangladesh. Clinical melioidosis has been reported in humans in Bangladesh as sporadic cases, with around 100 cases diagnosed over 60 years as of October 2023. There seems to be no inland reports on the prevalence of melioidosis in animals, even seroprevalence in Bangladesh. Objective: This study aimed to determine the seroprevalence of melioidosis in rural horses in Bangladesh using serological and molecular diagnostic techniques. Materials and Methods: From 2023 to 2024, a cross-sectional study was conducted in the Mymensingh, Jamalpur, and Kurigram districts of Bangladesh to determine the seroprevalence of melioidosis in local horses and associated risk factors. A total of 118 horse serum samples were collected and screened for melioidosis using the commercial kits of Antibody Rapid Detection Kit (ARDK), Enzyme-linked immunosorbent assay (ELISA), and Polymerase Chain reaction (PCR). Results: The overall seroprevalence was 21.53%, 15.25%, and 1.69% in the ARDK, ELISA, and PCR, respectively. Multiple epidemiological risk factors, including environmental conditions, husbandry practices, and geographical distribution, were evaluated and discussed. Conclusion: This study's findings may help us develop effective prevention and control strategies. There is a risk of zoonotic transmission of this disease to humans in contact with it. Further studies are needed to elucidate the epidemiology, pathogenesis, and clinical importance of melioidosis in animals and humans in Bangladesh, including its economic impact.