Clinical severity of Norwalk virus and Sapporo virus gastroenteritis in children in Hokkaido, Japan

Objective. To clarify the clinical significance and etiologic impact of Norwalk virus (NV) and Sapporo virus (SV) in viral gastroenteritis in Japanese children. Study design. Two outbreaks each of NV gastroenteritis and SV gastroenteritis occurring in an infant home in Sapporo, Japan, as well as 95 hospitalized children with acute gastroenteritis were retrospectively evaluated using a 0- to 20-point clinical severity scoring system. Result. The mean severity scores for NV and SV gastroenteritis outbreaks were 7.9 and 5.2, respectively, as compared with 8.4 for rotavirus A gastroenteritis that occurred in the same infant home. Among 95 hospitalized children with acute gastroenteritis, rotavirus A was detected in 47% followed by NV in 18%. SV was not found. Conclusion. Our data indicate that NV can cause severe gastroenteritis and is an important etiologic agent in hospitalized cases, whereas SV causes mild gastroenteritis in Japanese children.