Human Parechovirus 1 is the most prevalent genotype of human parechoviruses (genus Parechovirus, family Picornaviridae). This non‑enveloped, positive‑sense RNA virus has an icosahedral capsid and a genome of about 7.3 kb. Originally isolated in 1956 and once classified as echovirus 22, it was later reclassified as a parechovirus. The virus spreads through respiratory droplets and the fecal‑oral route and primarily infects infants and young children, leading to widespread seroprevalence by early childhood.
Virology and clinical features
Human parechovirus 1 replicates in the cytoplasm of host cells by translating its RNA genome into a polyprotein that is cleaved into structural and non‑structural proteins. It preferentially infects intestinal and respiratory epithelium and can survive in the environment for extended periods, facilitating transmission. Infections usually present as mild febrile illnesses, gastroenteritis, or upper respiratory tract symptoms. Some children develop a rash resembling erythema infectiosum. Although it is common in childhood, severe disease is rare; central nervous system involvement is uncommon in HPeV‑1 infection. Diagnosis is made by reverse‑transcription PCR from stool, throat swabs or cerebrospinal fluid. There is no specific antiviral therapy; management focuses on supportive care. Prevention relies on good hand hygiene and proper handling of diapers and respiratory secretions.
Historical observations and epidemiology
After its discovery, human parechovirus 1 was detected worldwide, with most children developing antibodies by the age of five. Seasonal peaks occur in summer and early autumn, and outbreaks have been reported in daycare settings. Seroprevalence studies show that adults have high neutralizing antibody titres, indicating past infection. Because HPeV‑1 typically causes mild disease, it is often underdiagnosed, but surveillance programs using molecular assays have improved detection. Cases requiring hospitalization tend to involve young infants, but long‑term sequelae are uncommon. Research is ongoing to understand the virus’s interactions with the human immune system and its potential role in chronic gastrointestinal disorders. Human parechovirus 1 remains a frequent but often overlooked cause of childhood gastroenteritis and respiratory illness. Early life exposure leads to lasting immunity, and severe complications are rare. Awareness of its transmission routes can help reduce spread, particularly in childcare settings. Related Terms: Human Parechovirus 3, Echovirus 11, Enterovirus D68, Human Rhinovirus A, Enterovirus A71.