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Malaria antigens found in breast milk of asymptomatic mothers

More than 15% of breast milk samples from mothers with asymptomatic malaria contain malaria antigens, according to a study published in JAMA Pediatrics, which showed that blood levels of malaria antigens may determine their levels in breast milk.

“We think the presence of malaria antigens in breast milk may lead to two possible consequences — either stimulating specific immune responses or reducing specific immune responses due to induction of immune tolerance,” Thomas Egwang, BVM, PhD, founding director and CEO of Med Biotech Laboratories, told Healio. “If the antigen in question is a target of protective immunity, then this could translate into a reduced or increased risk of malaria. We need to do a prospective follow-up of children breastfed on milk containing antigen in order to test this hypothesis.”

Egwang and colleagues collected breast milk samples from lactating mothers who visited a single malaria clinic in northeastern Uganda during the high or low malaria transmission seasons. They collected samples from 123 and 201 mothers during the low and high transmission seasons, respectively, and tested the samples for the presence of malaria antigens pHRP-2 and pLDH.

None of the mothers had clinical malaria, whereas 14 of the low-transmission season mothers and 74 of the high-transmission season mothers had asymptomatic malaria (P < .001). Among the breast milk samples from mothers with asymptomatic malaria, seven had detectable levels of pHRP-2 and 10 had detectable pLDH. In total, 14 (15.9%) of the samples were positive for either pHRP-2 and pLDH and three were positive for both antigens.

Egwang noted that the analysis is the first study to detect malaria antigens in human breast milk, and that future research could benefit from follow-ups among children of mothers with malaria.

“We took breast milk at only one time point and from moms at different stages of lactation,” Egwang said. “We also did not follow up the children to see if breastfeeding on milk containing antigen affected malaria outcomes. In future studies, we will recruit moms at the same stage of lactation and follow them up over time to see how long they shed antigens.”

Egwang also emphasized that until further testing is performed, breastfeeding should still be encouraged. “We still have a lot of follow-up work to do,” Egwang said. “Breast milk is safe and offers the best nutrition for infants, and breastfeeding within an hour of birth and for at least 6 months should be promoted.”

(Source: Van den Elsen LWJ, et al. JAMA Pediatr. 2020;doi:10.1001/jamapediatrics.2019.5209.)