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.

Differential distribution of hepatitis C virus subtypes in Asia: comparative study among Thailand, Indonesia, the Philippines and Japan.

Hepatitis C virus (HCV) is currently classified into at least six major genotypes, each of which is further divided into a number of subtypes. It has been reported that prevalence of each subtype varies among different geographical regions of the world and that severity of liver disease and sensitivity to interferon treatment varies with different subtypes. The purpose of this study was to determine and compare the prevalence of each subtype among HCV isolates in different areas in Asia such as southern (Hat Yai) and northern (Chiang Mai) parts of Thailand, Indonesia (Surabaya), the Philippines (Manila) and Japan (Kobe). Sera were obtained from various groups of patients and tested for antibodies against HCV using second and/or third generation ELISA kits. RNA was extracted from anti-HCV-positive sera and reverse-transcribed into cDNA. The cDNA-preparations were subjected to nested PCR to amplify NS5B and 5'-untranslated region (5'UTR) sequences. Amplified fragments were sequenced and subtypes of the isolates were determined based on sequence similarities with reported sequences. In Chiang Mai and Hat Yai, Thailand, HCV-3a, HCV-1a and HCV-1b were common in various populations. HCV type 6 variants were commonly found among blood donors and drug addicts in Chiang Mai, but not in Hat Yai. In Surabaya, Indonesia, HCV-2a was frequently detected in blood donors, but less frequently in patients with chronic liver disease. In blood donors, HCV-1a, HCV-1b and HCV-1d were more strongly associated with elevation of serum aminotransferase levels than HCV-2a. HCV-1a was significantly more common in patients on maintenance hemodialysis than in blood donors or patients with chronic liver disease. HCV-1d was detected exclusively in Indonesia. Another unique subtype HCV-3g was found also in Indonesia, though less frequently than HCV-1d. In the Philippines, a vast majority of the isolates were either HCV-1a or HCV-1b. Thus, HCV subtype prevalence varies among different regions of Asia.