Disease Severity High for Travelers With Norovirus-Positive Acute Gastroenteritis

Although norovirus-positive acute gastroenteritis is uncommon among travelers, the clinical severity of the infection is higher than norovirus-negative disease. These study results were published in The Journal of Travel Medicine.

This prospective, multisite, observational study was conducted among adults who traveled to areas with moderate to increased risk for travel-acquired acute gastroenteritis between March 2015 and July 2017. The primary outcome was the incidence of acute gastroenteritis caused by norovirus. Study participants provided self-collected stool samples 1 week before travel and self-reported symptoms during travel. All participants who developed symptoms and a sample of asymptomatic participants were requested to provide additional stool samples within 14 days of return. Real-time quantitative polymerase chain reaction was used to test stool samples for norovirus. Samples that tested positive for norovirus were subsequently genotyped.

Participants included in the final analysis (N=1109) were primarily women (60.1%), more than 60% were younger than 45 years, 27.5% had preexisting health conditions, and 78.4% had traveled for at least 7 days. Of note, participants’ baseline characteristics were similar between those who tested positive vs negative for travel-acquired acute gastroenteritis.

A total of 437 (39.4%) reported acute gastroenteritis symptoms during travel. Stool samples collected from 646 participants following travel showed 21 (3.3%) were positive for norovirus, including 1 obtained from an asymptomatic participant. Of the stool samples positive for norovirus, most were attributed to genogroup GII (85.7%).

During a follow-up period of 1769 person-weeks, the estimated total incidence was 24.7 per 100 person-weeks (95% CI, 22.4-27.1) for acute gastroenteritis and 1.1 per 100 person-weeks (95% CI, 0.7-1.7) for norovirus-positive acute gastroenteritis.

Although similar symptoms were observed between norovirus-negative and norovirus-positive participants, those who were positive for norovirus were more likely to report more frequent symptoms. The most commonly reported symptoms included abdominal gurgling/bloating (87.4%) and a sense of urgency for bowel movement (80.5%). The duration of illness was longer among participants who were positive vs negative for norovirus (3 vs 2 days), and norovirus-positive participants were more likely to have moderate (10% vs 4.0%) or severe (15% vs 2.8%) disease.

Limitations of the study include failure to reach the targeted sample size, the small number of norovirus-positive stool samples, and potentially limited generalizability.

According to the researchers, “The incidence data obtained here are relevant to guide future studies and the development of drugs to prevent or treat travel-acquired AGE [acute gastroenteritis], including potential vaccines against NoV [norovirus] infection and other enteric pathogens.”

Disclosure: This research was supported by Takeda Pharmaceuticals International AG. Some study authors declared affiliations with pharmaceutical companies. Please see the original reference for a full list of disclosures.