Parechoviruses – Underestimated Risk

Parechoviruses are small, non-enveloped, icosahedral-shaped capsid viruses belonging to the Picornaviridae family. They are characterized by a single-positive-strand genomic RNA and as others RNA viruses have a great potential for genetic variation, the rapid evolution and adaptation. Genus Parechovirus has been established in the 90s and currently, 19 types of human parechoviruses (HPeV) are discovered. They usually cause mild respiratory or gastrointestinal illness, mainly in young children, but also can cause severe diseases such as encephalitis, meningitis, myocarditis, acute flaccid paralysis and sepsis. Severe HPeV infections in infants are also associated with a risk of long-term complications. Although it is known that HPeV plays a significant role in severe pediatric diseases, routine diagnostics are not performed in clinical practice. No antiviral drugs have been approved for the treatment of HPeV infections, and only symptomatic treatment is available. Increased detection of human parechovirus infection in infants and connection of serious clinical complication with parechovirus infection was the reason why surveillance was established in some countries, while the worldwide extensive surveillance needs to be performed in order to monitor prevalence, genetic diversity, and clinical significance of HPeV. Although the first HPeV strains were discovered 6 decades ago, recognition of HPeV biology, epidemiology, evolution and pathogenicity still requires more research to appreciate the risk for public health that these small viruses can be. 1. Introduction. 2. Classification, structure and replication. 3. Cellular receptors and HPeV variability. 4. Course of infection 5. HPeV types in the world 6. Diagnosis 7. Pathogenesis 8. Summary