Association between breastfeeding, host genetic factors, and calicivirus gastroenteritis in a Nicaraguan birth cohort

ABSTRACT Background Norovirus and sapovirus are important causes of childhood acute gastroenteritis (AGE). Breastfeeding prevents AGE generally; however, it is unknown if breastfeeding prevents AGE caused specifically by norovirus and sapovirus. Methods We investigated the association between breastfeeding and norovirus or sapovirus AGE episodes in a birth cohort. Weekly data on breastfeeding and AGE episodes were captured during the first year of life. Stools were collected from children with AGE and tested by RT-qPCR for norovirus and sapovirus. Time-dependent Cox models estimated associations between weekly breastfeeding and time to first norovirus or sapovirus AGE. Findings From June 2017 to July 2018, 444 newborns were enrolled in the study. In the first year of life, 69 and 34 children experienced a norovirus and a sapovirus episode, respectively. Exclusive breastfeeding lasted a median of 2 weeks, and any breastfeeding lasted a median of 42 weeks. Breastfeeding in the last week did not prevent norovirus (HR: 1.09, 95% CI: 0.62, 1.92) or sapovirus (HR: 1.00, 95% CI: 0.82, 1.21) AGE in a given week, adjusting for household sanitation, consumption of high-risk foods, and mother’s and child’s histo-blood group phenotypes. Maternal secretor-positive phenotype was protective against norovirus AGE, whereas child’s secretor-positive phenotype was a risk factor for norovirus AGE. Interpretation Exclusive breastfeeding in this population was short-lived, and no conclusions could be drawn about its potential to prevent norovirus or sapovirus AGE. Non-exclusive breastfeeding did not prevent norovirus or sapovirus AGE in the first year of life. However, maternal secretor-positive phenotype was associated with a reduced hazard of norovirus AGE. WHAT IS KNOWN – Breastfeeding prevents acute gastroenteritis (AGE) in nursing infants. – It is unknown if breastfeeding prevents AGE caused by norovirus or sapovirus, which are leading causes of childhood AGE worldwide. – Host genetic factors can influence AGE risk, and the mediating effects of breastfeeding are unclear. WHAT IS NEW – Exclusive breastfeeding was rare, and breastfeeding did not prevent norovirus (hazard ratio 1.09, 95% CI: 0.62, 1.92) or sapovirus (hazard ratio 1.00, 95% CI: 0.82, 1.21) AGE. – Secretor-positive phenotype of the child and the mother may be more important than breastfeeding in determining norovirus and sapovirus AGE risk in this setting.