RV vaccination in NIP has led to a major reduction of hospital admissions and clinic visits due to RVGE, but has had no effect on NVGE. After 2 years of NIP, NV has become the leading cause of acute GE in children seen in hospital.

We examined stool specimens for viral pathogens from 50 children referred to hospital due to acute gastroenteritis (AGE) resulting from consuming drinking water contaminated with sewage in a Finnish community using PCR methods. Rotavirus was detected in 33 (66%), human calicivirus in 31 (62%), and both in 40% of cases. Of the caliciviruses, 20/31 (65%) were noroviruses and 11 (35%) sapoviruses. Furthermore, Aichi virus was detected in 25 (50%), adenovirus in six (12%) and bocavirus in four (8%) cases. Campylobacter jejuni was present in 20 (61%) and Salmonella in four (12%) of the 33 stools cultured for bacteria. On a 20-point scale median severity score of AGE in the 28 hospitalized children was 17; the severity was similar regardless of viruses detected. Bloody diarrhoea occurred only when C. jejuni was present. To conclude, massive exposure to several AGE viruses caused mixed infections and severe AGE regardless of the aetiological agents.

Noroviruses (NoVs) are the second most common cause of viral gastroenteritis after rotavirus in children. NoV genotype GII‐4 has emerged as the major type not only in outbreaks of NoV gastroenteritis but also endemic gastroenteritis among infants and young children worldwide. Using baculovirus‐insect cell system virus‐like particles (VLPs) of NoV genotype GII‐4 and an uncommon genotype GII‐12 were produced. These VLPs were used in enzyme‐linked immunosorbent assays (ELISA) for detection of NoV‐specific immunoglobulin G (IgG) and IgA antibodies in 492 serum specimens from Finnish children 0–14 years of age collected between 2006 and 2008. NoV IgG antibody prevalence was 47.3% in the age group 7–23 months and increased up to 91.2% after the age of 5 years. Avidity of NoV IgG antibodies was low in the primary infections while high avidity antibodies were detected in the recurrent infections of the older children. In GII‐4 infections, the homologous antibody response to GII‐4 VLPs was stronger than to GII‐12 VLPs but cross‐reactivity between GII‐4 and GII‐12 was observed. Binding of GII‐4 VLPs to a putative carbohydrate antigen receptor H‐type 3 could be blocked by sera from children not infected with NoV during a waterborne outbreak of acute gastroenteritis. Therefore, protection against NoV infection correlated with strong blocking activity. J. Med. Virol. 83:525–531, 2011. © 2011 Wiley‐Liss, Inc.

This study shows that all known non-SARS HCoVs can be found in stools of children with acute gastroenteritis. On the basis of this study, the significance of coronaviruses as gastrointestinal pathogens in children appears minor, since most of the coronavirus findings were co-infections with known gastroenteritis viruses.