Background: Giardia lamblia is one of the most prevalent protozoa infections of the human small intestine. Although anyone can be infected by Giardia, women and children are more susceptible. Giardia infection can cause malnutrition, diarrhea and indigestion of fat. In this study, the effect of breast-feeding on the prevalence of Giardia among children is investigated.

Methods: A total of 482 children, aged 6 to 24 months, from the urban areas of Semnan, Damghan and Garmsar in Iran, were enrolled in this survey. Each mother underwent an interview and filled out a questionnaire that included mother's age, family size, birth order of the child, age and sex of the child and type of milk consumed, among other variables. Then, each mother was given a sample container with 30cc of phenol alcohol formaldehyde (PAF) and an applicator for sampling her child's stool. Each mother was trained to consecutively sample her child's stool for three days, to put the stool into the provided container using the applicator and to shake it until the sample and liquid appeared homogenous. The sample was examined using the direct method, using formalin-ether and thionine. Data was analyzed using the c² test and logistic regression using SPSS version 11.5.
Results: The mean age of the children was 13.6(±5.6) months. Of these children, 45.6% were girls. The prevalence of G. lamblia infection was 8.5%. There was a significant relationship between Giardia and the age of the child, education level of the mother and type of milk the child consumed (p<0.05), such that children who had not consumed their mothers' milk were more likely to be infected compared to those who had been breast fed (OR=2.38, 95% CI: 1.13-5.03, P=0.023).
Conclusions: Results show that breast-feeding is a safer method of feeding with regard to Giardia infection. Therefore, mothers should be educated to breast-feed their children and not use other types of milk or milk substitutes. This important issue must be considered by policy makers for education and subsidy programs.