Aichi virus (also called Aichivirus A or human Aichi virus) is a non‑enveloped positive-sense single‑stranded RNA virus in the genus Kobuvirus and family Picornaviridae. First identified after a 1989 gastroenteritis outbreak in Aichi Prefecture, Japan linked to raw oyster consumption, this virus is transmitted via the fecal‑oral route and causes enteric infections.
Explanation
Structurally, Aichi virus is a small non‑enveloped icosahedral virus about 30 nm in diameter. Its 8.3 kilobase positive‑sense RNA genome contains a 5′ untranslated region with a VpG protein and internal ribosome entry site followed by a 7.3 kb open reading frame encoding the leader protein, capsid proteins VP0, VP3 and VP1, and non‑structural proteins involved in replication. Viral entry occurs via receptor‑mediated endocytosis; replication and translation take place in the cytoplasm, and mature virions are released by cell lysis. Infection is generally self‑limiting and produces symptoms typical of acute gastroenteritis, including vomiting, diarrhea, abdominal pain and fever. Aichi virus replicates in the intestinal epithelium and is shed in stool. Environmental surveys detect the virus in sewage, groundwater, river water and shellfish. Serological studies demonstrate widespread exposure; one German study found antibodies in roughly 76 % of adults, comparable to Japanese seroprevalence. Isolates have been detected in Asia, Europe, South America and Africa, and multiple genotypes circulate in humans and animals. Transmission typically occurs via contaminated food or water; high prevalence in shellfish and sewage underscores the importance of proper hygiene and wastewater treatment. Severe disease is rare but can occur in immunocompromised individuals.
Epidemiology and Notable Characteristics
Aichi virus gained its name after a 1989 outbreak in Aichi Prefecture where raw oysters contaminated with sewage caused numerous cases of gastroenteritis. Since that initial report, surveillance has identified aichiviruses in sewage, shellfish and drinking water across Asia, Europe, South America and Africa. Serosurveys reveal that most adults possess antibodies, suggesting early‑life exposure; antibody prevalence in Germany and Japan exceeds 70 %. Multiple genotypes circulate, and related kobuviruses infect dogs, mice and cats. While infection in healthy individuals is usually mild or asymptomatic, chronic disease has been described in people with B‑cell deficiencies or advanced HIV infection. Aichi virus is an emerging pathogen of concern in food safety because it can persist in shellfish and resist environmental degradation. Molecular techniques such as RT‑PCR and genome sequencing have improved detection and enabled genotype classification.
Aichi virus is a widely distributed enteric virus of the Kobuvirus genus that primarily causes mild gastroenteritis but poses risks for immunocompromised patients. Its small, non‑enveloped RNA genome encodes a typical picornavirus polyprotein, and infection is spread via contaminated water and food. Ongoing monitoring of wastewater and shellfish, along with improved hygiene, can help reduce transmission.
Related Terms: Kobuvirus, Cosavirus A, Saffold virus, Salivirus A, Norovirus GI