An outbreak of group A rotavirus infection resulted in gastroenteritis among disabled adults in an isolated rehabilitation institution in Kobe, Japan. Of the 95 residents, 16 were diagnosed with rotavirus illness. The causative agent was a single strain of typical human group A rotavirus belonging to VP7 serotype G2, VP4 genotype P[4], and NSP4 genotype A. Mean duration of stay was significantly longer for residents with rotavirus illness (22.1+/-11.8 years) than for residents without the disease (13.5+/-10.6 years; P=0.01). Age, sex, disability and location of resident rooms displayed no significant relationships with illness. These observations suggest that long-term residence in a closed community, which might be related to absence of immuno-stimulation, represents a risk factor for rotavirus illness.

A large number of gastroenteritis outbreaks due to a norovirus GII/4 strain and its variants occurred during November and December 2006 in Kobe, Japan. Of the 118 outbreaks, 6 were foodborne and 112 were caused by person-to-person transmission in healthcare settings such as nursing homes and hospitals. The distribution of norovirus outbreaks in healthcare settings was skewed, particularly in the south coastal area. Moreover, several outbreaks occurred within 1 km 2 in various areas. Outbreaks in neighboring settings, especially within 1 km, and travel from the sources of outbreaks were risk factors for the spread of the norovirus. The use of ineffective disinfectants such as alcohol and benzalkonium chloride might also have helped to spread the infection.