Seasonal distribution of enteropathogens detected from diarrheal stool and water samples collected in Kathmandu, Nepal.

A total of 334 diarrheal fecal samples (from 210 males and 124 females) collected in Kathmandu, Nepal, were studied for various kinds of enteropathogens. Overall, 33% (111/334) fecal samples were positive for one or more enteropathogens. There was no difference in detection rates between males and females. Enteropathogen detection rates in summer, winter, spring, and autumn were 61% (40/66), 52% (45/87), 31% (25/81), and 25% (25/100), respectively. Altogether eight species of bacteria, three genera of viruses, and five species of protozoan parasites were detected with considerable seasonal variations. Among the bacterial isolates, enteropathogenic Escherichia coli topped the list followed by Vibrio sp. Only one sample had Shigella (S. sonnei). Rotavirus type A was the most frequently detected among the enteric viruses, followed by human enterovirus and human adenovirus, respectively. Among the enteric protozoan parasites, Giardia intestinalis was the most frequently detected followed by Cryptosporidium parvum. Detection of bacterial and protozoan pathogens showed a slightly high tendency in the summer season compared with that in the other seasons (p>0.05), whereas the detection of viruses was significantly high in the winter season (p<0.05). Of the total 57 water samples, 43 (75%) showed one or more bacterial species out of which 51% (22/43) were E. coli. Among the E. coli isolates, 68% were EPEC. Enterohemorrhagic E. coli (O157) was not detected.