Gastroenteritis in Auckland: An aetiological and clinical study

Rotavirus hospitalisation in New Zealand children under 3 years of age

OBJECTIVE

To describe the epidemiology of severe rotavirus gastroenteritis and to estimate the hospitalisation rates of this illness in New Zealand children under 3 years of age.

METHODS

Children under 3 years of age with acute diarrhoea admitted to 1 of 8 study hospitals between 1 May 1998 and 30 April 2000 were surveyed. Their socio-demographic, treatment and length-of-stay data were recorded and stool samples tested by a rotavirus-specific enzyme-linked immunoassay. National hospital discharge data for infectious diarrhoea (International Classification of Diseases, ninth revision, 003-009) were reviewed, allowing population-based estimates for rotavirus-related hospitalisation in New Zealand.

RESULTS

Of 2019 enrolled children, 1138 (56.4%) provided stools for testing, and of these 485 (42.6%) tested rotavirus positive. Rotavirus detection varied significantly by age (26.8% for 0 to 5 months, 42.5% for 6 to 11 months and 52.1% for children aged 12 to 35 months; P < 0.001), and by season (51.2% in winter/spring vs. 24.5% in summer/autumn; P < 0.001). While those infected with rotavirus were more likely to be dehydrated (50.6% vs. 37.4%; P < 0.001), their median hospital stay was similar (1.0 vs. 2.0 days; P = 0.09) to other children with acute gastroenteritis. The estimated national hospitalisation rate for rotavirus diarrhoea in children under 3 years, standardised for age and season, was 634 (95% CI 597, 672) per 100,000. In New Zealand, rotaviruses result in 1 in 52 children being hospitalised by 3 years of age.

CONCLUSIONS

Rotavirus diarrhoea is an important, potentially vaccine-preventable cause of hospitalisation in New Zealand children, especially during winter and spring seasons.

Trends in hospitalization and mortality from rotavirus disease in New Zealand infants

BACKGROUND

Rotavirus illness is associated with significant morbidity and mortality worldwide. We have examined trends in diarrheal disease in New Zealand children to determine the disease burden attributable to rotavirus and to estimate the proportion of hospitalizations preventable by vaccination.

METHODS

Hospital admissions data and laboratory records for 1994 to 1996, were obtained for children 0 to 4 years at four sites (serving -60% of the New Zealand population). Rotavirus disease burden was estimated using combined admissions and laboratory data. Severity of disease was estimated in a sample of 150 hospitalizations for rotavirus diarrhea, and the proportion of vaccine-preventable admissions was extrapolated. Mortality attributed to diarrheal causes was determined from national records for 1974 to 1993.

RESULTS

Between 1994 and 1996, 4436 children <5 years of age were hospitalized with diarrhea (1047/100000 children per year). Admissions associated with rotavirus were estimated at 1522 to 1535 (315 to 362/100000 annually). Infants between 6 and 17 months were most commonly affected (42% of all cases). More male children than female children were hospitalized (P < 0.001) and mean length of stay was calculated as 1.51 days (SD 2.35). Disease severity scoring revealed that 61.3 and 38.0% of admissions reviewed were severe and very severe, respectively. Deaths from diarrheal causes numbered 138 among children 0 to 4 years old for the 20-year period 1974 to 1993, with 18 deaths occurring between 1984 and 1993 (10 years).

CONCLUSION

Current vaccines control severe disease, suggesting that 72% of cases reviewed would be eligible for prevention. A full cost effectiveness analysis is required to demonstrate anticipated benefits of vaccination.

An eight-year study of the viral agents of acute gastroenteritis in humans: ultrastructural observations and seasonal distribution with a major emphasis on coronavirus-like particles

During an 8-yr period, 862 stool specimens from patients with gastroenteritis were examined by electron microscopy after negative staining with 2% phosphotungstic acid (pH 6.5). Forty-one percent of the specimens submitted over an 8-yr period were determined to be positive for virus or viruslike particles belonging to one or more of seven morphologically distinct viral groups. Coronavirus-like particles (CVLPs) were present in 69.8% of the positive stool specimens. Membranous profiles containing "complement-type" holes (10 nm in diameter) were identified in some preparations containing CVLPs. The second most prevalent viral agent found in stool specimens was the rotavirus (17% of all positive stools). The incidence of other viruses identified in the survey were as follows: adenovirus 4.5%, picorna/parvovirus agents 2.9%, Norwalk-like agent 2.9%, astrovirus 1.9%, and calicivirus 0.5%. Unclassified small round viruses (approximately 25-30 nm in diameter) represented 0.5%. It was also determined that there was a seasonal distribution in excretion of all viruses except for CVLPs. A greater number of viruses were identified in the cooler, drier months of the year.

Rotavirus infection in a small community

Serial titres of rotavirus specific IgG and IgM have been measured in children and adults living in a small community over a 2 1/4-year period. In all age groups the mean titres of rotavirus specific IgG and IgM rose and fell in parallel with the changes in frequency of gastroenteritis symptoms in the community but after the time when respiratory symptoms reached their peak. Gastroenteritis symptoms were seen most commonly in the children but were also frequent in adults, especially the women. Titres of rotavirus specific IgG changed with age, increasing through childhood into early adult life, but decreased thereafter only to increase again in those over the age of 50 years. Females had higher levels of IgG in all age groups but especially among the children and 30-49-year-old women. The high levels of IgG did not protect the young adults from symptomatic gastroenteritis. Detectable levels of rotavirus specific IgM occurred in all age groups but more commonly in children aged under 10 years and in young adults. Raised levels of IgM were uncommon in the elderly, who rarely suffered gastroenteritis symptoms. An epidemiological model is proposed in which the older members of the community act as a reservoir of rotavirus, passing the infection to the children, who then infect the young adults.

Escherichia coli in gastroenteritis of children in Auckland, New Zealand

A study of stool Escherichia coli in 60 children with gastroenteritis and 18 control children was carried out in Auckland, New Zealand in 1977. Toxigenic strains, heat labile and heat stable, predominated in the stools of only three children, all of whom had concomitant rotavirus. Classical enteropathogenic E. coli (EPEC) were found in patients and controls. Only one patient had many EPEC in the stool (086.H2), they were variably toxigenic and rotavirus was also present. No toxigenic serotype was isolated. Two potential pathogens were sometimes found. Overall there was no evidence for a substantial causative role for disease producing E. coli in these children.

A prospective clinical study of rotavirus diarrhoea in young children

The clinical and laboratory features of 96 children aged 6 to 36 months with acute rotavirus diarrhoea were compared to findings on 63 children of the same age with acute non-rotavirus diarrhoea. Of the rotavirus-associated cases 80% occurred between January and June. In general, the diarrhoea was more severe in these patients than in the others, but no difference was seen in duration of symptoms. Clinical features characteristic of rotavirus-associated cases included: dehydration and acidosis upon admission, vomiting, fever, neutropenia and sugar in the stools (Clinitest greater than or equal to 0.5%). In contrast, no difference was seen in the occurrence of respiratory symptoms (53% in the rotavirus, 62% in the non-rotavirus group), or in the presence of mucus strands, occult blood or leucocytes in stools. A combination of the above criteria may be helpful in the presumptive diagnosis of rotavirus diarrhoea.

The 30- to 54-nm rotavirus-like particles in gastroenteritis: incidence and antigenic relationship to rotavirus

The 30- to 54-nm rotavirus-like particles were observed in the stool specimens of 17 children with gastroenteritis. These small rotavirus-like particles were shown to be antigenically related to the commonly described 68-nm rotavirus using the techniques of immune electron microscopy and ELISA (enzyme-linked immunosorbent assay). Four specimens containing the small rotavirus-like particles were shown to contain an antigen of a common human rotavirus serotype (type 2). The findings of small rotavirus-like particles of different diameters sharing a common antigen with rotavirus type 2 cautions against the naming of new candidate viruses based on morphology alone. In addition, the shedding of pure populations of single-shelled rotaviruses, herein described, could be an unusual phenomenon which may occur only sporadically. The relationship of the smaller rotavirus-like particles to rotavirus morphogenesis is discussed.