Outbreak of Gastroenteritis in Adults Due to Rotavirus Genotype G12P[8] *

BACKGROUND:   Rotavirus is a common cause of acute gastroenteritis among children. Rotavirus infection in older children and adults is much less common due to acquired immunity from prior exposures during early childhood. In adults, rotavirus infection may have a variable course, which may lead to unrecognized mild or asymptomatic infections. Few rotavirus outbreaks among US adults have been reported in the literature. We describe an outbreak associated with genotype G12P[8] rotavirus among medical students, faculty and guests who had attended a formal dinner in a hotel setting in April 2013.

METHODS:   A standardized web-based questionnaire was distributed to assess event attendees’ symptoms and exposures; Fisher’s exact and chi-square tests were used to detect associations. A clinical case was defined as a person who developed diarrhea after attending the formal dinner.  A laboratory-confirmed case was defined as a person with rotavirus detected in stool by enzyme immunoassay (EIA) or reverse transcription-PCR assay (RT-PCR). 

RESULTS:   Among 334 formal dinner attendees, 136 (41%) completed a web-based questionnaire; 58 (43%) responders reported illness. The median age of ill respondents was 24 years (range 22-64 years), 49 (84%) were medical students and 11 (22%) of 39 reported being on clinical rotation at the time of the event. Symptom onsets ranged from 1 to 8 days after attending the formal event, with peak onset 3 days after the event. Predominant symptoms among the 58 cases included diarrhea (100%), fever (91%), abdominal pain (84%) and vomiting (49%). The median duration of illness was 2.5 days (range 1 – 5 days). Thirteen (22%) of 58 cases sought medical attention; none were hospitalized. Analysis of food exposures among survey respondents did not identify significant associations between any specific food or drink item and illness.  Three samples were obtained from ill attendees and were tested for pathogens by Illinois Department of Public Health and CDC laboratories. All 3 were negative for bacterial pathogens by culture, negative for norovirus by RT-PCR, and positive for rotavirus by EIA; genotyping identified rotavirus G12P[8] in the 3 samples. One additional sample tested by the affiliated university hospital laboratory was negative for bacterial pathogens by culture and positive for rotavirus by EIA.

CONCLUSIONS:   Rotavirus outbreaks may occur among generally healthy adults, including young adults, and can result in considerable morbidity. Health professionals should consider rotavirus as a cause of acute gastroenteritis in adults.