title: 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.
authors.affiliation: Department of Pediatrics, University of Texas Medical School, Houston.
authors.forename: A L
authors.initials: AL
authors.lastname: Morrow
authors.forename: R R
authors.initials: RR
authors.lastname: Reves
authors.forename: M S
authors.initials: MS
authors.lastname: West
authors.forename: M L
authors.initials: ML
authors.lastname: Guerrero
authors.forename: G M
authors.initials: GM
authors.lastname: Ruiz-Palacios
authors.forename: L K
authors.initials: LK
authors.lastname: Pickering
mesh_terms: D000818:Animals; D001942:Breast Feeding; D015331:Cohort Studies; D005243:Feces / Q000469:parasitology; D005260:Female; D005500:Follow-Up Studies; D016829:Giardia lamblia / Q000302:isolation & purification; D005873:Giardiasis / Q000453:epidemiology / Q000469:parasitology / Q000517:prevention & control*; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008800:Mexico; D011446:Prospective Studies; D012307:Risk Factors