rotavirus
rotavirus, any of a group of viruses in the family Reoviridae that are known as the leading cause of severe diarrhea in children worldwide. Rotaviruses grow in the cells lining the intestines, where they give rise to acute gastroenteritis, particularly conditions known as infantile diarrhea and winter diarrhea. The Latin word rota means “wheel,” and thus rotaviruses are named for their wheel-like appearance, which is apparent under a microscope. They are further characterized structurally as nonenveloped double-stranded RNA viruses.
By age five, nearly all children have experienced rotavirus infection. Infection generally does not cause severe illness, though some children require hospitalization, typically owing to dehydration. Because individuals do not gain natural immunity after infection, they can be infected again, sometimes within the same season. However, the first episode is generally the worst.
In countries with a temperate climate, such as the United States, acute gastroenteritis due to rotavirus is most frequent during the cooler months: major outbreaks occur between December and June. In tropical areas, infection occurs year-round. The peak age of risk runs from six months to two years. Groups at increased risk of rotavirus infection include premature infants, the elderly, and any individuals with a weakened immune system. Infant nurseries, day care centres, and nursing homes are common sites of outbreaks.
Rotaviruses are typically transmitted when food is contaminated by feces from an infected person. Many outbreaks probably develop when infected food handlers contaminate foods that required no further cooking, such as salads, sandwiches, and fruits. The usual sanitary measures that prevent infection by bacteria or parasites, such as cooking and use of antimicrobial cleaners, often fail to control rotavirus contamination. Rotaviruses can infect domestic and wild animals, providing further opportunities for spreading infection.
Symptoms of rotavirus infection usually develop after an incubation period of one to three days. They include vomiting, frequent bouts of watery diarrhea, and fever, which can last from four to eight days. In children, high fever is more frequent with rotavirus infection than with other forms of gastroenteritis. Because of the tremendous loss of fluids due to the severe diarrhea, dehydration is a danger. During the time they are ill, most children tend to feel weak and listless and have poor appetites. They may continue to vomit if they do eat, which exacerbates dehydration.
Diagnostic testing can identify rotavirus in a patient’s stool. During an outbreak, however, it can be assumed that any child who suddenly develops severe watery diarrhea is infected. There is no cure for rotavirus infection, but getting an adequate supply of fluids is crucial for recovery. Most children recuperate completely, but if diarrhea is very severe and the fluid and minerals lost from the body are not replaced, death may result. Some individuals never develop symptoms, though they can spread infection.
Infants who are breast-fed may gain some immunity if the mother’s milk contains antibodies against rotavirus. If such infants are subsequently exposed to rotavirus, these antibodies can destroy the virus before it has a chance to grow in large numbers and cause diarrhea. Vaccination against rotavirus is the most effective form of prevention. Rotavirus vaccine can be given orally and is safe and highly effective.
