The role of water physicochemical properties and hydrological connectivity on the presence of Burkholderia pseudomallei in the wetland environments, Northeast Thailand

Abstract

This study aims to examine the landscape and water physicochemical conditions of Burkholderia pseudomallei (B. pseudomallei) in the wetland systems of a rural area in northeast Thailand to gain a better understanding of the presence and survival of the bacteria in water environments. B. pseudomallei is the etiological agent for melioidosis, a disease that causes fatal septicemia (blood poisoning) and acute pneumonia (lung infections) in humans and animals. A total of 166 water samples were tested for the presence of B. pseudomallei. Of the 166 water samples, 136 were tested for the water physicochemical properties (pH, temperature, salinity, nitrate and iron concentrations). The results indicated that B. pseudomallei were prevalent in slightly acidic to neutral water with low salinity, low nitrates and low iron concentrations. B. pseudomallei were also found to thrive at an estimated optimum temperature of 29-32°C. The highest recovery of B. pseudomallei was from the rice wetland environments. Nonetheless, B. pseudomallei were detected in natural and man-made wetland environments. Sample sites with B. pseudomallei were generally located within the greater wetland region, while negative sample areas were located further away. The greater wetland region therefore acts as a large reservoir source for the bacterium. The containment of B. pseudomallei within the greater wetland region could be attributed to hydrological connectivity of the wetlands through floodwaters and irrigation systems. As the villagers’ livelihoods often revolve around water-related occupations such as rice farming, the presence of B. pseudomallei in their working environment contributes to high risk of exposure of villagers to the bacterium and melioidosis through direct contact with contaminated water. As such, this research urges preventive and precautionary measures and management to minimize the ii villagers' risk by reducing their physical exposure to the bacterium and, in turn, melioidosis.