Fecal Shedding of Virus in Relation to the Days of Illness in Infantile Gastroenteritis Due to Calicivirus

Fecal shedding of virus in relation to the days of illness was studied by electron microscopic examinations of stool specimens collected during two consecutive outbreaks of gastroenteritis associated with calicivirus in an orphanage in the city of Sapporo, Japan. Of 61 stool specimens examined, 29 (48%) were found to contain typical calicivirus particles. Although caliciviruses were found in none of the seven stools obtained by chance before the onset of illness, they were found in 18 (9507o) of 19 stool specimens collected within four days after the onset of illness. Seven (50%) of 14 specimens collected during the next five days were virus-positive, and the viruses were rarely detected in the stools collected thereafter. Thus correlation between viral shedding and the days of illness was clearly demonstrated. This finding should provide additional evidence for the etiologic role of calicivirus in acute infantile gastroenteritis. Caliciviruses of human origin were first found in stools of children with gastroenteritis by Madeley and Cosgrove [1] and Flewett and Davies [2] in 1976. Accumulating evidence has suggested the possible etiologic role of this virus in acute gastroenteritis in children [3-7]. Nevertheless, caliciviruses are among the viruses whose relationship to gastroenteritis is still being established, mainly because of the lack of epidemiologic evidence. We experienced an outbreak of acute infectious diarrhea associated with calicivirus in an orphanage and have described the details of the outbreak [6]. Recently, we experienced again an extensive outbreak of acute infectious diarrhea associated with caliciviruses in the same orphanage. On the basis of the electron microscopic (EM) examinations of the stools collected from the infants residing in the orphanage during the outbreaks, we found a close relationship between days of illness and patterns of viral shedding. The results are briefly described.