A Cluster of Hepatitis A Infections Presumed to be Related to Asari Clams and Investigation of the Spread of Viral Contamination from Asari Clams.

In a cluster of hepatitis A infections that occurred in Nagano Prefecture in 2017, hepatitis A virus (HAV) was detected in asari clams (reference food) and the patients' fecal samples. Initially, the asari clams were suspected to be the infection source. However, the exact infection route remained unknown because a patient who had not consumed an asari clam dish also developed the disease. Suspecting a secondary infection originating from the asari clams, we investigated the presence of HAV genomes in water used for washing and soaking the frozen asari clams and detected HAV in the soaking water. These results suggest that soaking water is a risk factor for secondary contamination because of the leakage of HAV accumulated in midgut gland of the asari clam. During the asari clam sand removal process, the water used to clean asari clams spread across a wide area in a concentric fashion, raising concerns that this process may aggravate contamination. In addition to HAV, diarrhea viruses, such as norovirus, have often been detected in bivalves, including asari clams. Thus, handling these foodstuffs requires adequate care.

Whole genomic analysis of human G8P[14] group A rotavirus detected from community gastroenteritis outbreak.

Several suspected cases of zoonotic transmission of group A rotavirus (RVA)-related gastroenteritis were reported previously. In August 2012, G8P[14] RVA was detected in fecal specimens from a community gastroenteritis outbreak occurring during a school trip. In this study, additional analyses were performed and it was found that this strain had the G8-P[14]-I2-R2-C2-M2-A3-N2-T6-E2-H3 sequence, similar to bovine-like RVA strains. Some contamination by emesis and diarrheic feces was observed near a rest room in the lodging area. Contact history with animals was unknown in members of this school trip, and this case implied that the strain may have acquired the ability for person-to-person transmission.

[An outbreak of gastroenteritis caused by norovirus: suspected due to dust transmission].

A norovirus gastroenteritis outbreak at a wedding reception hall in Nagano Prefecture in April 2008 affected that hall's reception participants and waiters, but not waiters or food handlers at another hall. To determine the infection route, dust in three vacuum cleaners used to clean the venue were tested for norovirus using real-time reverse transcriptase polymerase chain reaction (RT-PCR), with norovirus RNA detected from all three. Sequencing analysis of a 280-nt portion of the capsid region showed that 9 specimens from infected reception participants and waiters and dust samples had 100% nucleotide identity. This suggests that the infection route was dust transmission, that the reception venue floor had been contaminated with norovirus, and that participants and staff had been exposed to norovirus in dust during the wedding reception. Dust thus requires specific attention as a potential infection source because norovirus cDNA copies were 1.7 x 10(4) to 1.6 x 10(5) per gram in dust specimens.