Prevalence of human parechovirus in the Netherlands in 2000 to 2007.

Infection with human parechovirus 3 (HPeV3) was described for the first time in Japan in 2004 and reportedly is more often associated with severe disease than infection with HPeV1 or HPeV2. In 2004, infections with HPeV3 were observed for the first time in The Netherlands. Genetic analysis showed several different lineages, suggesting endemic circulation. We analyzed 163 cell culture isolates from the same number of patients tested in routine virological laboratories as part of the national enterovirus surveillance program. Isolates were collected between 2000 and 2007 and could not be characterized by routine methods. In total, 155 isolates (95%) were found positive for HPeV by a reverse transcription-PCR assay targeting the 5' untranslated region, explaining the majority of the diagnostic deficit in enterovirus surveillance for these years. Typing of the isolates by use of partial genome sequencing of the VP1/2A region revealed the presence of 55 HPeV1, 2 HPeV2, 89 HPeV3, 1 HPeV4, and 8 HPeV5 isolates. We compared isolation dates, age groups affected, and clinical pictures, which were reported as part of the routine surveillance. Clear differences in epidemiology were observed, with HPeV3 occurring at intervals of 2 years and in the spring-summer season, whereas HPeV1 was observed in small numbers throughout each year, with a low in the summer months. HPeV3 infection affected younger children than HPeV1 infection and was significantly more often associated with fever, meningitis, and viremia.