Rapid reinfection by Giardia lamblia after treatment in a hyperendemic Third World community.

In a peri-urban shanty town in Lima, Peru, that was hyperendemic for Giardia lamblia, 44 children aged between 0.9 months and 10 years were effectively treated for Giardia lamblia with tinidazole. Stools were examined weekly in the 6 months after treatment to determine the rate of reinfection, and after reinfection stools continued to be examined. 98% of the children became reinfected with Giardia lamblia within 6 months, and after reinfection stool excretion of the parasite lasted a mean (SD) of 3.2 (3.3) months. The children's mean stool pH and their mean stool fat index was unaffected by Giardia lamblia reinfection. Treatment of all symptomless Giardia lamblia infections in a developing country hyperendemic for the disease is of questionable value because of rapid reinfection.