An international team of researchers found that mothers' breast milk can provide protection against infection lasting for life and that the protection is brought by immune cells transfer.
The study published in the journal Science Advances showed that infant mice breastfed by a mother who had a worm infection before becoming pregnant acquired life-long protection against this infection.
It was previously believed that immunity against illness is passed from mother to baby for only the period they are breastfed and it was transferred through a mother's proteins such as antibodies.
"This is the first demonstration that infection prior to pregnancy can transfer life-long cellular immunity to infants," said the paper's corresponding author William Horsnell, who works across the University of Birmingham, the University of Orleans in France and the University of Cape Town in South Africa.
The effect was passed onto the infants by cells in the mother's milk and not proteins such as antibodies, according to the study.
This could lead to the design of new vaccines that will be able to be given to a mother to transfer long-term immunity to her children, according to the study.
Researchers from the University of Liege, University of Cardiff, University of Washington and University of Mainz also participated in the study.