Transmission of Giardia lamblia from a day care center to the community.

An outbreak of giardiasis was investigated in one urban day care center; another day care center was selected as a control. In the study day care center, 35 per cent of the children were infected. Infection was spread to at least one household contact of 47 per cent of the infected children. The data suggest person-to-person transmission of giardiasis and the need for measures to prevent its dissemination. Early recognition and treatment of Giardia lamblia infections in children may be indicated.