Quantitative analysis of fecal sapovirus shedding: identification of nucleotide substitutions in the capsid protein during prolonged excretion.

Sapovirus (SaV) is an important pathogen causing gastroenteritis in humans. Quantitative analysis of the viral loads in feces collected from two SaV outbreaks was performed. Our results showed that SaV excretion generally decreased to an undetectable level in 2 weeks; however, some individuals excrete SaV in feces at high concentrations for 2-4 weeks after the onset of illness. In addition, we identified for the first time nucleotide changes in the capsid region during prolonged excretion.