Monitoring and identifying the sources of Giardia and Crytosporidium contamination in the Bangkok Chao Phraya River.

Abstract

Chao Phraya River is the Bangkok vital waterway for transportation as well as a source of consumption. Giardia and Cryptosporidium (oo)cyst contamination were monitored along this river bank during summer, rainy and winter seasons in order to study the seasonal variation and geographic distribution. The possible sources of those contaminations were then identified by using the genotyping method. Thirty water samples were collected from the North to the South of the river at 2 kilometers apart. Twenty-three percent were tested positive for Giardia with mean (min-max) concentration as 378.9 (125-982.8) cysts/1000L and 30% positive for Cryptosporidium with 247.2 (6.9-500) oocysts/1000L. The highest (oo)cyst contamination were found during the late rainy season. Two sources of surface-water contamination were identified as stray pet excreta run-off and household sewage. The prevalence of those two pathogenic protozoa correlated with the high population density of the riverside districts (mean 11,135 people/km2). However, the 3 inner city areas with high population density but well educated habitants revealed negative result for both protozoa. Noteworthy, in the Buddhist Temples the place of stray dogs and cats were the source of contamination. Health educations for people who live by the river, sewage treatment and attention on stray pet excreta management are needed for proper prevention and elimination schemes to circumvent a potential outbreak.