Enterovirus

Enteroviruses infect an estimated 50 million people each year in the US and possibly a billion or more worldwide. Approximately 75% of enterovirus infections occur in children under 15 years of age, and the occurrence rates are highest in children under 1 year of age. Transmission occurs orally, either via aerosol or ingestion of contaminated food. Approximately 50-80% of enterovirus infections are mild or asymptomatic; however, they can also develop into severe and life-threatening diseases. Serologic studies have distinguished over 70 human enterovirus serotypes associated with 26 different syndromes and diseases, including coronary heart disease, type 1 diabetes, hand-foot-and-mouth disease, polio, and meningitis. Traditionally, enteroviruses were classified into four separate species: coxsackie, echovirus, enterovirus, and poliovirus. However, due to large overlaps in their epidemiologic and clinical characteristics, their taxonomy has changed, and newly identified viruses are now numbered, starting with EV68. To date, the following enterovirus subtypes have been identified:

Subtype Diseases

Poliovirus 1-3 Paralysis, aseptic meningitis, encephalitis, poliomyelitis

Coxsackie A1-A24 Herpangina, hand-foot-mouth, common cold

Coxsackie B1-B6 Pleurodynia, aseptic meningitis, encephalitis, pericarditis, myocarditis

Echovirus 1-9, 11-31 Paralysis, aseptic meningitis, encephalitis

Numbered Enteroviruses Herpangina, hand-foot-and-mouth, conjunctivitis (EV70), aseptic meningitis (eg. EV71)

Enterovirus outbreaks are common in the summer and fall, though they can cause infections year-round in tropical parts of the world. Several serotypes have been responsible for large outbreaks including:

• Enterovirus 71: large outbreaks of Hand-Foot-and-Mouth Disease (HFMD) worldwide, especially in children in Asia
• Echovirus 13, 18, and 30: several outbreaks of viral meningitis in the United States
• Enterovirus D68: infected children in 49 states in 2014 and hospitalized them with severe respiratory illness
• Coxsackievirus A16 & A6: the most common cause of HFMD in the United States
• Coxsackievirus A24 & Enterovirus 70: seasonal worldwide outbreaks of acute hemorrhagic conjunctivitis since the 1970’s
• Poliovirus: killed over 500,000 people worldwide each year in the 1940’s and 50’s. Vaccines are now available