Definition of Enterovirus

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Enterovirus: A virus that enters the body through the gastrointestinal tract and thrives there, often moving on to attack the nervous system. The polioviruses are enteroviruses.

Enteroviruses are small viruses that are made of ribonucleic acid (RNA) and protein. In addition to the three different polioviruses, there are 61 non-polio enteroviruses that can cause disease in humans: 29 Coxsackieviruses (23 Coxsackie A viruses and 6 Coxsackie B viruses), 28 echoviruses, and 4 other enteroviruses.

The enteroviruses are second only to the "common cold" viruses, the rhinoviruses, as the most common viral infectious agents in humans. The enteroviruses cause an estimated 10-15 million or more symptomatic infections a year in the United States.

All three types of polioviruses have been eliminated from the Western Hemisphere by the widespread use of vaccines.

Enteroviruses can be found in the respiratory secretions (e.g., saliva, sputum, or nasal mucus) and stool of an infected person. Other persons may become infected by direct contact with secretions from an infected person or by contact with contaminated surfaces or objects, such as a drinking glass or telephone. Parents, teachers, and child care center workers may also become infected by contamination of the hands with stool from an infected infant or toddler during diaper changes.

Infections caused by enteroviruses are most likely to occur during the summer and fall. Most people who are infected with an enterovirus have no disease at all. Infected persons who become ill usually develop either mild upper respiratory symptoms (a "cold"), a flu-like illness with fever and muscle aches, or an illness with rash. Less commonly, some persons have aseptic or viral meningitis. Rarely, a person may develop an illness that affects the heart (myocarditis) or the brain (encephalitis) or causes paralysis. Enterovirus infections are suspected to play a role in the development of juvenile-onset diabetes mellitus (type 1 diabetes). Newborns who become infected with an enterovirus may rarely develop an overwhelming infection of many organs, including the liver and heart, and die from the infection.

There are usually no long-term complications from the mild illnesses or from aseptic meningitis. Some patients who have paralysis or encephalitis, however, do not fully recover. Persons who develop heart failure (dilated cardiomyopathy) from myocarditis require long-term care for their conditions.

No vaccine is currently available for the enteroviruses, aside from polio. General cleanliness and frequent handwashing are probably effective in reducing the spread of these viruses.