Environmental surveillance for Laribacter hongkongensis, a diarrhoeal pathogen discovered in Hong Kong

1. Laribacter hongkongensis was isolated from the midguts and hindguts of 86 (24%) of 360 freshwater fish from retail markets, including grass carp (60%), bighead carp (53%), mud carp (25%), and large-mouth bass (5%). 2. This study is the first to demonstrate the presence of L hongkongensis in natural water environments, with the bacterium being isolated from the waters of six reservoirs, with higher recovery rates in summer and during days of higher water and ambient temperatures. 3. Molecular typing using pulsed field gel electrophoresis revealed a heterogeneous population of L hongkongensis in both the freshwater fish and drinking water reservoir isolates, suggesting that the bacterium is endemic in our freshwater environments. 4. Since freshwater fish are common food items for our population, the general public should be educated on the proper preparation and thorough cooking of freshwater fish before consumption to avoid L hongkongensis-associated gastroenteritis. 5. Although it is unlikely that treated drinking water is a significant source of L hongkongensis-associated gastroenteritis, it is important to be aware of the possibility of other contaminated water as a source of human infection.