Bottle feeding as a risk factor for cholera in infants

To determine risk factors for cholera in infants, a retrospective matched-pair study of 42 cases and their controls was undertaken during an outbreak of El Tor cholera in Bahrain in the autumn of 1978. The highest attack-rate of cholera (125/10 000) occurred in infants in the 6--11 month age-group, which corresponds to the weaning age in this community. Significantly more cases than controls were principally bottle fed (greater than 50% milk intake by bottle) than principally breast fed during the week before onset of illness (p=0.004). Analysis of various patterns of breast and bottle feeding did not determine whether the protection afforded by breast feeding was a negative effect (due to the lack of exposure to contaminated bottle feedings for breast fed infants) or a positive effect (due to protective functions of constituents of human breast milk). Cholera infection (with or without symptoms) among mothers of either case or control infants was uncommon (case mothers 3, control mothers 5), and mean serum vibriocidal and antitoxic antibody levels were similar for the two groups of mothers. These observations suggest that maternal infection did not affect the relative risk of infants having symptomatic cholera.