In October 1977 an outbreak of acute infectious diarrhea occurred in an infant home in the city of Sapporo, Japan. Of 34 residents aged two to 20 months, 26 (77%) suffered from diarrhea. In ten of these patients the diarrhea was accompanied by vomiting. Electron microscopic examinations revealed typical calicivirus particles in eight faecal specimens, seven of which were from the group of 26 affected patients (28%) and one of which was from the group of eight infants without symptoms (13%). Immune electron microscopy tests for antibody responses against one of the isolated strains of calicivirus were carried out on 27 paired pre- and post-outbreak sera. Seroconversions were demonstrated in 18 of 19 (95%) affected infants and in six of eight (75%) unaffected infants. One patient with lack of antibody response was the youngest child--two months old. Periodic surveys on enteric viruses circulating in the home revealed that calicivirus was specifically associated with the outbreak of gastroenteritis. These observations provide further evidence for the causative role of calicivirus in acute gastroenteritis in children.

Breast-fed infants are susceptible to human cytomegalovirus (HCMV) infection via breast milk. In our previous study, HCMV was isolated more frequently from breast milk at later than one month after delivery than from colostrum or early breast milk. To clarify the role of milk cells and whey in vertical infection by breast feeding, we separated breast milk into milk cells and whey and examined each fraction for the presence of HCMV. We collected breast milk from mothers who breast-fed their infants (aged from 3 days to 2 months). The breast milk was centrifuged and separated into the middle layer (layer of milk whey) and the pellet (containing milk cells). We attempted to isolate HCMV from whey and to detect HCMV immediate early (IE) DNA in both milk whey and cells. HCMV was isolated from 7 out of 35 (20.0%) whey samples and HCMV IE DNA was detected from 15 out of 35 (42.9%) whey and/or milk cells. Detection rates of HCMV IE DNA in the whey layer and milk cells were 39.1% (25 out of 64) and 17.2% (11 out of 64), respectively. HCMV IE DNA was not detected in colostrum, but was detected in breast milk samples one month after delivery. Therefore, cell-free HCMV shed into milk whey may have a more important role in vertical infection by breast milk than cell-associated HCMV in the milk. Human cytomegalovirus (HCMV) infection occurs by vertical, horizontal and iatrogenic transmission. In Japan, over 90% of healthy adults acquire the HCMV IgG antibody and over 60% of healthy infants are infected with HCMV during the first year of life (15). Vertical transmission includes transplacental transmission, transmission due to contact with virus-containing secretion in the birth canal, and transmission by feeding infected breast milk. Transplacental transmission that was assessed by viruria of neonates is assumed to have an incidence of 0.2-2.2%. In Japan, as 11-28% of pregnant women in the late stage of gestation shed HCMV into genital tract secretions (15), genital tract secretion was regarded as a main source of infection. Since Diosi et al (5) succeeded in isolating HCMV from breast milk, breast milk has been considered as one of the most important sources of mother-to-infant infection. Hayes et al (7) isolated HCMV from breast milk of 17 out of 64 seropositive women (27%) and most of the isolates were obtained after the first week. Stagno et al (17) reported that breastfed infants are more frequently infected with HCMV than bottle-fed infants based on the rate of isolation from urine. Moreover, Dworsky et al (6) reported that consumption of infected breast milk led to infection in 69% of infants. Isolation of HCMV from colostrum showed a lower incidence than breast milk at more than one month after delivery. Breast feeding seemed to be associated more closely with vertical infection than contact with an infected genital tract. In past studies of our laboratory, Hotsubo et al (8) reported the results of virus isolation and the detection of HCMV DNA for late antigen (LA) in milk samples of seropositive mothers a...

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 (95%) 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.

Serum specimens from children and adults living in Saporo, Japan, were tested for antibody against human calicivirus by immune electron microscopy (IEM), using virus-rich faecal extracts as the source of antigen. Of 83 serum specimens tested, 49 (59%) were positive for calicivirus antibody. Age-related prevalence of antibody to calicivirus was as follows: 23% (3/13) in the 0-5-month-old group, 30% (6/20) in the 6-23-month-old group, 65% (13/20) in the 2-5-year-old group, and 90% in school children (18/20) and adults (9/10). As for IEM antibody ratings scored from 0 to 4, almost all positive sera from older infants and preschool children scored 3 to 4. Antibody scores were rather more scattered in school children. The results indicated that caliciviral infection is prevalent in younger children in this part of Japan.

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