An epidemiological study of rotavirus diarrhoea in a cohort of Nigerian infants: II. Incidence of diarrhoea in the first two years of life

Abstract

In a community-based prospective study of diarrhoeal diseases carried out in Ibadan, 131 infants were selected at birth. The maximum possible length of follow-up ranged from 16 to 24 months. Weekly surveillance for diarrhoea was carried out at home by Primary Health Care workers. Each child was also required to attend a monthly clinic. Of the 131 babies, 95 (73%) completed at least one year of follow-up. All of these had at least one episode of diarrhoea within the first year of life. The incidence rate of diarrhoea in the first year of life was 3.2 cases/child/year. The mean duration of diarrhoea days in the first year of life was 16 per child per year (range 3-34 days). The peak incidence of diarrhoea and the greatest number of diarrhoea days were in the age interval 6-9 months. The mean duration of diarrhoea was five days per episode. Faecal samples for 280 diarrhoea episodes during the first year of life were examined for rotavirus using the ELISA technique: 22 (7.7%) were found to be positive. The mean duration of rotavirus diarrhoea episodes was eight days.

PIP: Researchers studied the incidence of diarrheal diseases in a cohort of 131 infants in Ibadan, Nigeria Primary health care workers visited each infant every week to learn of any diarrheal episodes. In additions, each child was to attend a clinic monthly for further evaluation. Of these infants recruited at birth, 95 (73%) finished 1 year of follow up. The incidence rate for acute diarrhea was 3.2 episodes/child, and each infant experienced at least 1 episode. For those infants aged 6-8 months, the incidence rate was 9 episodes/100 child weeks which was the highest mean incidence rate of all the age groups (ranging from 0-2 months to 18-23 months). In addition, the highest number of diarrhea days/child was for this same age group and it was 5.2 days/child/interval. In the 1st year of life, the mean number of diarrhea days/child/year was 16 (range 3-34) and the mean duration of each episode was 5 days. Additionally, laboratory personnel examined 280 fecal samples from diarrheal episodes for rotavirus. 22 (8%) of these were positive and the majority of these cases occurred in infants 3-5 months old. Rotavirus diarrheal episodes ranged from 5-12 days with a mean of 8 days. 12 (55%) of the infants who tested positive for rotavirus were males, and the mean duration was longer for them (8.4 days) than for the females (7 days), but the difference was not significant. The rotavirus infections caused no deaths. In addition, none of the infants with rotavirus had a 2nd episode of rotavirus infection during the surveillance period.