Enteroviruses, from the Picornaviridae family, causes numerous kinds of infections in animals and humans, especially in children. They spread through the fecal-oral route by patients with poor hygiene, or through direct contact with secretions of patients, especially among those living in close quarters. Contact with fecal materials while changing diapers or washing infected children, can sometimes lead to accidental transfer of the virus to the nose, eyes and mouth. Common diseases associated with enteroviruses can range from mild to severe, and include conjunctivitis, meningitis, and myocarditis. There are five types of enteroviruses: poliovirus, echovirus, enterovirus, coxsackie virus A, and coxsackie virus B.
The enteroviruses can survive outside the body for many days, and they can also resist the acid pH in the gastrointestinal tract. Once viruses enter the human body, they stay in the gastrointestinal tract or respiratory tract to incubate for three to ten days or more. During this period, infected persons can transmit the virus to other people through their secretions and stool. Usually after about three days, the viruses multiply and spread into the bloodstream, resulting in the manifestation of symptoms such as fever, headache, sore throat, muscle pains, and diarrhea. Symptoms of infections with subtypes of enteroviruses are usually mild and resolve after seven to ten days.
Other organs of the body are frequently affected, depending on the type of virus present. Polioviruses often reach the central nervous system (CNS), causing the death of nerve cells, and often leading to paralytic poliomyelitis. Coxsackie virus A spreads to the pharynx, causing herpangina, while coxsackie virus B usually infects the heart muscles, causing myocarditis. Echoviruses, on the other hand, can infect the liver, lungs, heart muscles, and skin, while enteroviruses have been implicated in epidemic conjunctivitis and in hand, foot and mouth disease. All five types can spread to the brain and cause meningitis.
Many enteroviruses can be isolated in the laboratory for identification and diagnosis. Samples are usually taken from the blood, stool, cerebrospinal fluid (CSF), and throat swabs. In many cases, however, the signs and symptoms of the illness, profile of patients affected, occurrence of disease outbreaks, and history of exposure can greatly help physicians come up with a diagnosis.
Treatment comprises mostly of supportive measures like rest, drinking plenty of fluids, and taking medicines for relief of fever and pain. The advent of polio vaccine led to the eradication of polio virus infection in most developed countries. Spread of infection is higher in lower socioeconomic status areas, often in people living in crowded living spaces and with poor sanitary practices. Infections with enteroviruses are common during the summer months, and in tropical climates, it can occur for the whole year.