Rotavirus is a virus that infects the bowels. It is the most common cause of severe diarrhea among infants and children throughout the world and causes the death of about 600,000 children worldwide annually. The name rotavirus comes from the characteristic wheel-like appearance of the virus when viewed by electron microscopy (the name rotavirus is derived from the Latin rota, meaning "wheel").
Almost all children have become infected with rotavirus by their third birthday. Repeat infections with different viral strains are possible, and most children have several episodes of rotavirus infection in the first years of life. After several infections with different strains of the virus, children acquire immunity to rotavirus. Children between the ages of 6 and 24 months are at greatest risk for developing severe disease from rotavirus infection. Adults sometimes become infected, but the resulting illness is usually mild.
Each year in the U.S., rotavirus infection results in the hospitalization of an estimated 55,000 children, 200,000 emergency-room visits, and 400,000 visits to doctor's offices. It is estimated that 100 children die each year in the U.S. from complications of rotavirus infection. Rotavirus affects populations in all socioeconomic groups and is equally prevalent in industrialized and developing countries, so differences in sanitation practices or water supply are not likely to affect the incidence of the infection.
In the U.S., rotavirus infections usually peak in the fall months in the Southwest and spread to the Northeast by spring, so infections are most common during the winter months from November to May. However, infection with rotavirus can occur anytime of the year.
While children are the predominant victims of rotavirus infection, adults (often caretakers or parents of these children) may experience the same symptoms of fever (50%-60%), vomiting, and non-bloody diarrhea (both 85%).
Studies have shown a broad range of response to rotavirus infection - all the way from total lack of symptoms to severe illness that may be associated with dehydration and circulatory collapse. Hospitalized patients often have a total duration of disease averaging eight days. As would be expected, those who are less ill and may remain at home tend to have less intense symptoms and generally recover more quickly.
Some studies of children with rotavirus infection have pointed out that 30%-50% have respiratory symptoms (runny nose and cough) coexistent with their intestinal manifestations. Other researchers counter that an alternative interpretation of these findings implies two separate but simultaneous illnesses. Adults tend not to experience respiratory symptoms during a rotavirus illness.
Complications of rotavirus infection are relatively rare. Important exceptions are those infections in people with weakened immune systems (premature and newborn infants or the elderly). When access to modern medical supportive care is available (for example, IV solutions) severe morbidity and death are rare. However in developing nations, where such services are scarce or unavailable, rotavirus infection may be life-threatening.
Infectious gastroenteritis (vomiting and diarrhea) may be caused (in order of frequency) either by viral, bacterial, or fungal agents. There are four viral families that cause the bulk of gastroenteritis. As stated above, rotavirus is responsible for the large majority of illness both worldwide and in the United States.
Infection by the norovirus family is implicated in approximately one-third of all viral illnesses causing vomiting and diarrhea. Two other viral families (adenovirus and astrovirus) each cause approximately 5% of intestinal disease.
How Is the Virus Transmitted?
Large amounts of rotavirus are shed in the stool of infected people. This contaminated stool can easily spread to hands and objects. Because rotavirus is stable in the environment - meaning the virus can live for a long time outside of a host - rotavirus transmission can occur quite easily through the following methods:
- Ingestion of contaminated food or water.
- Direct contact with contaminated surfaces.
Children can spread rotavirus both before and after they become sick with diarrhea. They can sometimes pass the virus to other members of the family and to close contacts.
Rotavirus can also be transmitted to adults. An adult rotavirus infection is less common and usually less severe. In adults, infection is most often seen in:
- Family members of affected children.
- Older individuals.
- People with conditions or medications that decrease the function of the immune system, such as people with HIV, AIDS, or cancer.
Once the rotavirus has entered the body, it travels to the small intestine, where it begins to multiply. Approximately two days later, rotavirus symptoms can begin. This period between infection and the beginning of symptoms is known as the "rotavirus incubation period".
If outpatient management fails, intervention with IV fluids generally is necessary to correct dehydration, provide appropriate replacement fluids for ongoing losses due to vomiting and diarrhea, and guarantee administration of daily maintenance fluids.
Various formulas to calculate the necessary volume and composition of these fluids as well as their rate of administration are available. Correction of moderate to severe dehydration may require up to 24 hours. Accurate monitoring of intake (oral and IV) and output (vomiting and diarrhea) is imperative. Infants and toddlers should have daily weight measurements obtained.
Antibiotics have no place in the management of rotavirus-induced illness. A number of other therapeutic options have been developed to help control the symptoms of gastrointestinal illnesses. While some may have anecdotal benefit, they are generally not recommended for use in children.
These include over-the-counter antimotility drugs (for example, Imodium), which may tend to relieve the frequency and volume of diarrhea as well as lessen associated cramping. Pepto-Bismol is an over-the-counter preparation claiming to lessen the secretory capacity of the intestinal tract. Since it is metabolized to an aspirin-type product, it should not be used in people less than 18 years of age. Some products (for example, Kaopectate) promote their value as adsorbents.
There are some medications that have demonstrated conclusive benefits to control and correct symptoms of rotavirus gastroenteritis. Administration of probiotics (for example, Lactobacillus species) is felt to be helpful in reestablishing the normal intestinal bacterial population. An antiemetic developed to control chemotherapy-induced vomiting (Zofran) has been shown to be safe and effective.
Zinc supplementation has also been shown to be effective in controlling diarrhea. The effectiveness is most pronounced when treating children with chronic malnutrition in whom zinc deficiency is most likely to occur.