Protection against infection with Giardia lamblia by breast-feeding in a cohort of Mexican infants

Abstract

To determine whether breast-feeding protects infants against symptomatic and asymptomatic infection by Giardia lamblia, we followed 197 infants in a poor area of Mexico City from birth to 18 months of age; symptoms and feeding status were recorded weekly. Stool specimens were collected every 1 to 2 weeks and tested for Giardia by enzyme-linked immunosorbent assay. A mean of 1.0 Giardia infection per child-year was detected; 94 infants had a total of 139 infections; 17% of infections were symptomatic. Ninety-one percent of infants were breast fed from birth and 38% were breast fed at 1 year of age. Lack of breast-feeding was a significant risk factor for first Giardia infection at all ages. The adjusted incidence rate ratio for first Giardia infection for none versus complete breast-feeding was 5.0 (confidence interval (CI) 1.5 to 16.9; p = 0.009), and for none versus any breast-feeding, 1.8 (CI 1.1 to 2.8; p = 0.013). Symptomatic Giardia infection was also associated with lack of breast-feeding (none vs any: incidence rate ratio = 2.5; CI 0.9 to 6.8; p = 0.077), but breast-feeding did not protect against chronic carriage of Giardia. Other significant risk factors for Giardia infection were presence of animals in the household (p = 0.005) and the use of water or nonmilk liquid for infant feedings (p = 0.035). We conclude that breast-feeding protects infants against Giardia by mechanisms that include preventing the establishment of infection.

PIP: To determine whether breast feeding protects infants against symptomatic and asymptomatic infection by Giardia lamblia, the authors followed 197 infants in a poor area of Mexico City from birth to 18 months of age. Symptoms and feeding status were recorded weekly. Stool specimens were collected every 1-2 weeks and tested for Giardia by an enzyme-linked immunosorbent assay. A mean of 1.0 Giardia infection/child-year was detected; 94 infants had a total of 139 infections and 17% were symptomatic. 91% of the infants were breast fed from birth and 38% were breast fed at 1 year of age. Lack of breast feeding was a significant risk factor for 1st Giardia infection across all ages. The adjusted incidence rate ratio for 1st Giardia infection for none vs. complete breast feeding was 5.0 (confidence interval [CI] 1.5-16.9; p=0.009), and for none vs. any breast feeding, 1.8 (CI 1.1-2.8; p=0.013). Symptomatic Giardia infection was also associated with a lack of breast feeding (none vs. any; incidence rate ratio=2.5; CI 0.9-6.8; p=0.077), but breast feeding did not protect against chronic carrying of the infection. Other significant risk factors for Giardia infection were: presence of animals in household (p=0.005) and the use of water or nonmilk liquid for infant feedings (p-0.035). The authors conclude that breast feeding feeding helps protect infants against Giarda by mechanisms which include the prevention of infection invasion at the outset.