Can Giardia lamblia infection lower the risk of acute diarrhea among preschool children?

There are inconsistent findings concerning the role of Giardia lamblia in pediatric diarrhea. A prospective cohort study of the incidence of acute diarrhea among Israeli Arab preschool children offered the opportunity to examine the association between G. lamblia infection (at baseline) and subsequent diarrhea. Following baseline screening by light microscopy for the presence of Giardia in their stools, a cohort was assembled of 142 children who were followed between October 2003 and August 2004 for the incidence of diarrhea. Surveillance was performed through maternal interviews. At baseline, 21 children tested Giardia-positive. During the prospective surveillance, acute diarrhea occurred less often among Giardia-positive children (9.5%) than among children who were not infected with Giardia (26.5%). G. lamblia infection was associated with lower risk of acute diarrhea; adjusted odds ratio of 0.18 (95% confidence interval 0.04-0.93) (p = 0.041). This prospective study provides additional evidence that Giardia may lower the risk of subsequent acute diarrhea among preschool children.