Norovirus is the worldwide leading cause of gastroenteric diseases. It affects mainly infants and older adults, but the findings are mainly derived from outbreak investigations rather than population-based cohorts. The U. S. Naval Medical Research Unit SOUTH (NAMRU SOUTH) developed and conducted research studies in the last 20 years focusing on the military and general populations afflicted by this pathogen. For the latter, studies included all age groups in 2 main communities in Peru, representing people from the highlands and tropical areas. The results helped elucidate the incidence of norovirus infection among different age groups as well as identifying risk factors, seasonality, and economic burden on the patient. The collected data demonstrate an increase of norovirus cases, not only in the previously reported age groups but also in adults. Consequently, this increase of norovirus cases in adults may impair the occupational productivity in civilian populations and operational readiness among service members.