Lack of an adverse effect of Giardia intestinalis infection on the health of Peruvian children

Abstract

Giardia intestinalis is a common gastrointestinal protozoan worldwide, but its effects on childhood growth in developing countries are not clearly understood. The authors aimed to describe its effects on child growth. They followed 220 Peruvian children daily for diarrhea, weekly for stool samples, and monthly for anthropometry. The authors modeled the effect of nutritional status on the risk of Giardia infection and the risk of diarrhea attributable to Giardia using negative binomial regression. They modeled the effects of Giardia infection on growth using linear regression, with 85% of children becoming infected with Giardia and 87% of these becoming reinfected. In multivariable analysis, the risk of Giardia infection did not vary with weight for age (relative risk = 1.00, 95% confidence interval: 0.89, 1.12) or height for age (relative risk = 0.92, 95% confidence interval: 0.82, 1.04). Giardiasis did not affect growth at 1 or 2 months following the first infection at any age interval. The longitudinal prevalence of Giardia between 6 and 24 months of age was not associated with height gain in that interval (p = 0.981). Giardia was not associated with an increased risk of diarrhea at any age interval. Study results question the importance of Giardia as a childhood pathogen in developing countries where giardiasis is hyperendemic.

FIGURE 1.

Duration of Giardia episodes for children living in Las Pampas de San Juan, Lima, Peru, between 1995 and 1998. Duration is expressed in weeks (w) or months (m). Each bar represents the percentage of Giardia episodes that lasted a specific number of weeks or months. The numbers above the bars represent the number of episodes that lasted a specific number of weeks or months.

FIGURE 2.

Unadjusted incidence and prevalence of Giardia by categories of weight for age, Lima, Peru, 1995–1998. We estimated incidence as the number of new Giardia episodes per 52 child-weeks and prevalence of Giardia as the proportion of Giardia-positive child-weeks. The bars represent the incidence of Giardia, and the filled circles connected by lines represent the prevalence of Giardia. Although single-variable analysis suggests that the risk of giardiasis varies with weight for age, in the adjusted model we did not find an association between infection with Giardia and weight for age (relative risk = 1.00, 95% confidence interval: 0.89, 1.12).

FIGURE 3.

Unadjusted incidence and prevalence of Giardia by categories of height for age, Lima. Peru, 1995–1998. We estimated incidence as the number of new Giardia episodes per 52 child-weeks and prevalence of Giardia as the proportion of Giardia-positive child-weeks. The bars represent the incidence of Giardia, and the filled circles connected by lines represent the prevalence of Giardia. “*” indicates that there were insufficient data points in the category of height-for-age z score greater than 2 to accurately estimate the incidence or prevalence of Giardia. Although single-variable analysis suggests that the risk of giardiasis varies with height for age, in the adjusted model we did not find an association between infection with Giardia and height for age (relative risk = 0.92, 95% confidence interval: 0.82, 1.04).