Viral Causes of Diarrhea

Abstract

Rotavirus is the most commonly recognized viral pathogen that produces diarrheal disease in children and the most common cause of severe gastroenteritis requiring hospitalization. However, a number of other viruses can cause diarrhea, and their clinical manifestations are important to recognize in the care of children who have gastroenteritis. The viruses include adenovirus, Norwalk virus, astrovirus, and calicivirus.Some generalizations can be made about viral diarrheal disease in infants and young children. Incubation periods are brief, usually 1 to 3 days. Infections can be asymptomatic, but if diarrhea develops, it frequently is associated with vomiting and fever. With the exception of rotavirus, the diarrhea produced by viral infection typically is mild to moderate. If stool studies are performed, they rarely reveal white blood cells or occult blood in the stool, and results of stool cultures are negative.Second only to rotavirus in frequency is adenovirus, which accounts for 5% to 10% of pediatric hospitalizations for acute gastroenteritis (compared with the 30% to 70% attributed to rotavirus). Serotypes 40 and 41 are the enteric strains known to cause gastroenteritis in children; these strains do not cause any of the respiratory symptoms commonly associated with other adenoviruses. The mean age of clinical illness in children is 1 to 2 years of age. Like rotavirus, transmission is by the fecal-oral route. Adenovirus has an incubation period of 8 to 10 days, which is considerably longer than that of the other common viruses. Symptoms last 5 to 12 days on average, with one third of children experiencing diarrhea for longer than 14 days. Patients may have vomiting or fever with adenoviral infection. Unlike rotavirus, there is very little seasonality associated with adenoviral gastroenteritis. An enzyme immunoassay test is available for detection of adenovirus, but it is not used frequently outside of research studies.Norwalk virus is also an important cause of viral gastroenteritis. This virus is spread both by the fecal-oral route and via contaminated food and water sources. Outbreaks of diarrheal disease can occur in child care, schools, and other settings, commonly affecting older children and adults. The incubation period is usually less than 48 hours. Unlike adenovirus, the course of illness with Norwalk virus gastroenteritis is brief, lasting fewer than 48 hours, and generally is characterized by vomiting.Less commonly recognized causes of viral diarrhea include astroviruses and caliciviruses. Astrovirus infections can be asymptomatic, but also can cause diarrheal illness, with more than 50% of children also experiencing vomiting and fever. Detected most commonly in the winter, astroviruses have a short incubation period of 1 to 2 days. Caliciviruses also can cause mild diarrhea in infants and toddlers, although symptoms are seen in older children and adults as well. Both of these virus families have been associated with outbreaks at child care centers and in association with consumption of contaminated food or water.The primary concern for all diarrheal disease is prevention and treatment of dehydration. Oral rehydration solutions, which are very effective in preventing and treating dehydration, are commercially available for children, and appropriate intravenous solutions may be used for fluid resuscitation of patients who do not tolerate oral fluids. All of the viral gastroenteritides are self-limited, and antibiotics play no role in their treatment.Comment: Worldwide, viruses are the leading cause of diarrhea. Among viruses, rotavirus is the major cause of severe diarrhea (Pediatr Rev. 1999;20:39–71). Unfortunately, vaccines have not provided the answer to rotaviral disease prevention. Handwashing and ensuring safe food and water supplies continue to be the mainstays of prevention of viral diarrhea.Tina L. Cheng, MD, MPHAssociate Editor, In Brief