Enterovirus infections

Enteroviruses reproduce in the gastrointestinal tract after an infection butdon't lead to intestinal symptoms; they causes disease by spreading to organssuch as the nervous system, heart, and skin. There are four groups ofenteroviruses: Coxsackievirus, Echovirus, ungrouped Enterovirus, and Polio virus; the first three are covered here. Enteroviruses are found worldwide, but are more common in areas of poor hygiene and overcrowding. Although most cases do not produce symptoms, 5-10 million people in the United States each year suffer from an enteroviral disease. Illness is more common in the very young, including fetuses. The virus is usually transmitted by fingers or objectscontaminated by human waste material; it can also be transmitted through contaminated food or water. The incubation period for most enteroviruses rangesfrom 2-14 days. Enteroviruses are believed to be the cause of at least 10 illnesses. Once they enter the body, they multiply in the lining of the gastrointestinal tract, and eventually reach lymphatic tissue (such as the tonsils).While most don't last long and cause no significant injury, some can make theperson severely ill. The most common syndrome caused by enteroviruses is summer grippe (nonspecific febrile illness), which has flu-like symptoms of fever, headache, and weakness, and typically lasts three to four days. Many patients also develop upper respiratory symptoms and some nausea and vomiting. Generalized disease of the newborn is a potentially serious infection with symptoms of fever, irritability, and decreased responsiveness or excessive sleepiness, which is difficult to distinguish from a severe bacterial infection. Inflammation of the heart muscle (myocarditis), low blood pressure, hepatitis, and meningitis sometimes complicate the illness. Aseptic meningitis encephalitis, most often in children and young adults, causes headache, fever, avoidance of light, eye pain, drowsiness, and possibly sore throat, cough, muscle pain, and rash. Occasionally, the brain tissue is affected, producing encephalitis. The illness goes away after a week or so, and permanent damage is unusual. Enteroviruses can also produce the Guillian-Barré syndrome, which involves weakness and paralysis of the extremities and the muscles of respiration. Pleurodynia (Bornholm's disease) is due to viral infection and inflammation of the chest and abdominal muscles used for breathing. Pain occurs as acute episodes, lasting 30 minutes or so. Myocarditis and/or pericarditis involves infection of the heart muscle (myocardium) and the covering around the heart (pericardium). Infants and young adults are the most susceptible. The disease usually begins as an upper respiratory tract infection with cough, shortness of breath, and fever. Chest pain, increasing shortness of breath, irregularities of cardiac rhythm and heart failure sometimes develop. Some patients wind up with long-term heart failure. Enterovirus rashes are the number one cause of exanthems (rashes) in the summer and fall. They occur anywhere on thebody, and often resemble diseases such as measles.

In most cases, diagnosis is based on the symptoms that the virus produces. Itis not usually necessary to identify a specific strain of virus causing theillness. Cultures are only helpful when obtained from areas that indicate recent infection, such as from swollen joints, cerebrospinal fluid, or blood. New techniques to identify viral genetic material (PCR) are useful in certain cases, but are not routinely used. Enterovirus can attack many different organs and produce a variety of symptoms. Most infections are mild, improve without complications, and require no specific therapy. When the virus attacks critical organs such as the heart, respiratory muscles, or nervous system, specialized care is often needed. There is no effective antiviral medication for enterovirus. In some patients antibodies (hypogammaglobunemia) are given. The outlook for enterovirus infection depends on the organs involved and the immune condition of the patient. Infection causes few problems unless vital organsare involved, immunity is abnormal, or patients have diseases that affect antibody production. In the hospital setting, the best way to avoid transmitting infection is good hand-washing practices and gowns and gloves for hospitalstaff. Precautions which isolate waste material will help decrease the chanceof spreading the illness.

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