Are waterborne astrovirus implicated in acute digestive morbidity (E.MI.R.A. study)?

BACKGROUND: With rotavirus and Norwalk-like viruses, astroviruses are now recognized as important etiologic agents of viral gastroenteritis in all age groups. However, astrovirus is neither routinely screened for in stool samples, nor in environmental samples, and data on the health impact of waterborne astrovirus are lacking. OBJECTIVES: To assess the potential impact of astrovirus in drinking water on the incidence of acute digestive conditions (ADC) among a panel of volunteers. STUDY DESIGN: The Epidemiology and MIcrobial Risk Assessment (E.MI.R.A.) study combined a daily epidemiological follow-up of digestive morbidity among a panel of 544 volunteers supplied by French public water systems, and a microbiological surveillance of drinking water. Cases of digestive morbidity were collected through weekly telephone calls. The bacterial, virological and parasitic quality of tap water was assessed monthly. Additional samples were collected if the incidence of ADC increased. The relationship between incidence of ADC during a 7-day period centered about the water sampling day and astrovirus RNA prevalence in drinking water was modeled by regression techniques, taking into account several confounders. RESULTS: 12% (8/68) of the analyzed water samples were positive for astrovirus, and presence of astrovirus RNA was associated with a significant increased risk of ADC: RR=1.51 (95% CI=[1.17-1.94], P value=0.002). CONCLUSIONS: This result suggests a role for waterborne astrovirus in the endemic level of digestive morbidity in the general population. Perhaps astrovirus is a candidate test target for viral surveillance of drinking water.