Epidemiology of human parechovirus, Aichi virus and salivirus in fecal samples from hospitalized children with gastroenteritis in Hong Kong.

BACKGROUND: Emerging human picornaviruses, including human parechovirus (HPeV), Aichi virus (AiV) and salivirus (SalV) were found to be associated with gastroenteritis, but their roles in enteric infections are not fully understood. In addition, no report on the circulation of these viruses in Hong Kong is available. The objective of this study was to investigate the prevalence and genetic diversity of HPeV, AiV and SalV in fecal samples from hospitalized children with gastroenteritis in Hong Kong. METHODS: Fecal samples from hospitalized children with gastroenteritis were subject to detection of HPeV, AiV and SalV by RT-PCR using consensus primers targeted to their 5'UTRs. Positive samples were subject to capsid and/or 3CD region analysis for genotype determination. The epidemiology of HPeV, AiV and SalV infections was analyzed. RESULTS: Among 1,708 fecal samples subjected to RT-PCR using primers targeted to 5'UTR of HPeV, AiV and SalV, viruses were detected in 55 samples, with 50 positive for HPeV only, 3 positive for AiV only, 1 positive for both HPeV and AiV, and 1 positive for both HPeV and SalV. Phylogenetic analysis of the partial VP1 gene of the 33 HPeV strains revealed the presence of genotypes of HPeV- 1, 3, 4, 5, 7, 10, among which HPeV-1 was the predominant genotype circulating in our population. The peak activity of HPeV infection was in fall. Of the 3 children with AiV infection, the 3 AiV strains were found to belong to genotype A based on the phylogenetic analysis of their partial VP1 and 3CD regions. The genotype of a SalV strain detected in this study could not be determined. Co-detection of different pathogens was observed in 24 samples (43.6%) of 55 fecal samples positive for HPeV, AiV and SalV. CONCLUSIONS: HPeV, AiV and SalV were detected in fecal samples of hospitalized children with gastroenteritis in Hong Kong, with the former having the highest prevalence. HPeV-1 was the predominant genotype among HPeVs, while genotype A was the predominant genotype among AiVs in this study.

Streptococcus suis in retail markets: how prevalent is it in raw pork?

Streptococcus suis present in raw pork meats sold in local retail markets was enumerated by Most Probable Number (MPN)-PCR method. This method combined the conventional MPN technique with a specifically designed PCR assay based on the amplification of a 294-bp S. suis species-specific 16S rRNA gene sequence. A total of 78 raw pork lean meat samples purchased at two different supermarkets (Site A and B) and a wet market (Site C) were tested. Results indicated that S. suis could be detected from the enriched MPN tubes of all, except one, sample homogenates. The concentration of S. suis ranged from <3 to 4600 MPN/g of pork meat, with a total bacterial count (TBC) varying from 3.6 log to 7.4 log CFU/g. Statistical analyses indicated that pork meats purchased from the supermarket at Site B in summer contained significantly higher concentration of S. suis organisms than those from other retailers in any season. A significant correlation existed between log S. suis concentration and log TBC of the samples. This study revealed that raw pork meats available in local supermarkets or wet markets could contain S. suis at concentrations that were usually difficult to detect with traditional culture method. Field application of this method may contribute to a measurable evaluation, and thus the effective control, of human S. suis infection due to raw pork or pig carcass handling.