[S12-3] Study on the spread of cholera disease in Kolkata, India
Kolkata area has been said to be hot-bed area of cholera. Cholera patients emerge throughout the year in Kolkata area. In addition, the emergence of cholera patients is sporadic and a collective outbreak in certain areas has not been generated in the Kolkata area. This indicates the Kolkata area is suitable for surviving of Vibrio cholerae O1. Then, we studied the habitat of V. cholerae O1 in the Kolkata region. First, we investigated the surviving of V. cholerae O1 in the environmental water of Kolkata area. We found that both groundwater and pond water in Kolkata area contain higher amounts of ions compared than those of Japanese water and that V. cholerae O1 survived for long time in the groundwater from Kolkata. This indicates that the environmental water of Kolkata is suitable for surviving of V. cholerae O1. Subsequently, we analyzed the stools of both diarrhea patients and healthy persons in the vicinity of cholera patients using the metagenomic sequencing. The result showed that V. cholerae often causes subclinical infections in Kolkata residents. The subclinical infections appeared to be associated with the spread of cholera disease in the Kolkata region.