Parechoviruses, a novel group of human picornaviruses

Parechoviruses are a recently established group of human viral pathogens. A t the time of their first isolation, parechoviruses were classified among t he enterovirus genus in the picornavirus family, but based on their differe nt biological properties they were separated into their own genus. The type member is human parechovirus 1 (HPEV1), which frequently infects humans, i n particular small children. The parechovirus genus also includes HPEV2 and the Ljungan virus, which was recently isolated from rodents, is a candidat e for the group. Seroepidemiological studies have shown that the prevalence of HPEV1 antibodies is surprisingly high, exceeding 95% in adult populatio ns. According to present data, HPEV1 causes mainly gastrointestinal and res piratory infections, however, severe disease conditions, such as myocarditi s and encephalitis, have also been reported. HPEV2 infections appear to be rare, and it is currently not known whether the Ljungan virus can infect hu mans.