5 - Enteroviruses

Summary

The viruses

Enteroviruses are RNA viruses belonging to the family Picornaviridae, to which rhinoviruses (which cause the common cold) also belong. More than 70 serotypes exist. Coxsackie A, Coxsackie B, echoviruses and polioviruses are all different serotypes of enteroviruses. Because of the similarity in viral genome, later serotypes were just called enterovirus followed by a sequential number e.g. enterovirus 71 (EV71), enterovirus 72 (EV72) etc.

Epidemiology

Route of spread

As the name implies these are spread by the enteric route by faecal–oral spread, e.g. by ingesting contaminated food or water.

Prevalence

Enteroviruses are endemic worldwide and a very common infection of childhood. Young children are often infected with more than one enterovirus at a given time. Because of poor standards of hygiene, infection is extremely common in the developing world. Polio, which is caused by an enterovirus, has been eradicated from most of the countries in the world following massive vaccination campaigns under the World Health Organization (WHO) expanded programme of immunizations (EPI). The countries where polio is still considered to be endemic by WHO are India, Pakistan, Nigeria and Afghanistan, and although not endemic it has been reintroduced in a handful of other countries (from where it had been eradicated) in the African and Asian sub-continents.

Outbreaks of infections with different serotypes causing particular clinical manifestations, e.g. conjunctivitis, hand foot and mouth disease, occur from time to time.

Incubation period

Variable, generally 3–7 days, with 7–14 days for polio.