Norwalk virus shedding after experimental human infection.

The magnitude and duration of virus shedding in faeces of persons experimentally infected with Norwalk virus was evaluated. Of 16 persons, clinical gastroenteritis (watery diarrhoea and/or vomiting) developed in 11; symptomatic illness lasted 1-2 days. Virus shedding was first detected by reverse transcription-PCR (RT-PCR) 18 hours after infection and lasted a median of 28 days (range 13-56 days). The median peak shedding was 95 x 10(9) (range 0.5-1, 640 x 10(9)) genomic copies/g faeces as measured by quantitative RT-PCR. Virus shedding was first detected by antigen ELISA approximately 33 hours (median 42 hours) after innoculation and lasted 10 days (median 7 days) after innoculation. Emerg Infect Dis. 2008;14(10):1553-7.