IDSA: Rotavirus Infection, Not Just for Kids

SAN DIEGO, Oct. 11 -- Rotavirus infection, once considered almost exclusively a pediatric diarrheal disease, affects adults as well, causing substantial morbidity and unnecessary use of procedures and antibiotics, according to results of a study reported here.

From February through May 2006, rotavirus was identified in about three times as many bacterial stool cultures as all other bacterial pathogens combined, Evan J. Anderson, M.D., of Northwestern University in Chicago, told attendees at the Infectious Diseases Society of America.

"Rotavirus is an under-recognized pathogen in adults who have diarrhea requiring hospitalization," Dr. Anderson concluded. "More studies are needed to better characterize the illness in older adults, including risk factors."

Rotavirus is extremely common in children; 95% have been infected at least once by age 5, said Dr. Anderson. The most severe infections involve children ages six months to two years. But the burden of rotavirus diarrheal disease in adults in the United States has been unknown, he continued, although episodes have been reported in travelers to Mexico and Central America.

Little is known about the clinical presentation of the infection in adults, either. In studies of healthy volunteers exposed to the pathogen, 39% developed symptoms, half shed virus in stool, and 65% had antibody responses (Lancet Infect Dis 2004; 4: 91-99). Contact with children is known to be a risk factor for rotavirus infection in adults.

To explore both areas, Dr. Anderson and colleagues retrospectively reviewed records on hospitalized patients who had bacterial stool cultures from December 2005 through November 2006. The study included patients who had been hospitalized for less than 72 hours and excluded patients younger than 18 and those who had formed stool specimens.

Of 1,046 stool specimens, 620 were available for testing with a rotavirus assay. The virus was detected in 18 (2.9%) of samples, and the monthly detection rate was 0 to 6.5%.

Positive tests showed a distinct seasonality, as 10 of 202 specimens (5%) tested positive for rotavirus from February through May 2006, compared with eight of 418 specimens (1.9%) from June 2006 through the end of the study period.

"The overall rate of rotavirus in blood stool cultures from hospitalized adults with diarrhea is the same as that of all other bacterial pathogens combined," said Dr. Anderson. "During the peak pediatric rotavirus season [February through May], rotavirus in adults is about three times more common than all bacterial pathogens combined."

As compared with patients who tested positive for bacteria in their stool, the rotavirus cohort was older (median age 51 versus 35), had traveled outside the U.S. less frequently (6% versus 30%), and was more likely to be immunosuppressed (41% versus 12%). Moreover, 18% of the rotavirus cohort had HIV infection, compared with none of the patients with bacteria in their stool.

Clinical findings differed between the rotavirus and bacteria patients only with respect to chills, which were reported by 12% of the rotavirus cohort and 67% of the patients with bacteria in their stool. The only major difference in laboratory findings was in the proportion of patients who had a BUN/creatinine ratio >20:1; 29% of the rotavirus cohort had a ratio that high, none of the other patients did.

Dr. Anderson reported that 29% of the rotavirus patients had CT scans, 29% underwent endoscopy or surgical procedures, and 53% received antibiotics. Additionally, mortality in the rotavirus cohort was 12%, whereas no patient in the bacterial group died.