Controlled trial of Giardia lamblia: control strategies in day care centers

Strategies for control of Giardia lamblia in day care differ in numbers of children treated and in costs to parents and day care operators. The effectiveness of these strategies has not been systematically evaluated. We conducted a prospective randomized controlled trial comparing three strategies for control of Giardia in infant-toddler day care centers: Group 1, exclusion and treatment of symptomatic and asymptomatic infected children; Group 2, exclusion and treatment of symptomatic infection only; Group 3, exclusion and treatment of symptomatic infection, treatment of asymptomatic infection in the center. The study included 31 day care centers with 4180 child-months of observation. Giardia prevalence was determined before intervention and 1, 2, 4, and 6 months later; new infants and toddlers were tested on admission. Initial Giardia prevalences were 18% to 22% in the three groups. Giardia was identified in 10.5% of 676 new infants and toddlers entering study day care centers during the 6-month follow-up. Giardia prevalences by intervention group were 8%, 12%, and 7% at 1 month, and 7%, 8%, and 8% at 6 months. The stricter intervention resulted in greater cost in terms of child day care and parents' work days lost, but did not result in significantly better control of Giardia infections in this day care environment.