"Under normal circumstances, the body is very hostile to anything foreign," co-author Alex Wamachi, a researcher at the Kenya Medical Research Institute in Nairobi, told SciDev.Net.
Babies are generally protected by antibodies provided by their mothers for the first six months of life, the authors say.
But once this immunity is gone children up to the age of three have an increased susceptibility to malaria.
This susceptibility, coupled with immune tolerance, says Wamachi
, is "a recipe for disaster".
When undetected, the malaria parasite finds its way into red blood cells where it matures.
Eventually it leaves to multiply, destroying many red blood cells in the process - reducing the body's capacity to carry oxygen and resulting in anaemia.
says the factors determining newborn tolerance are unclear but could be related to a mother's own immune response during a malaria infection.
The researchers hope their findings will have implications for the design of future malaria vaccines for this age group.
"For now we are happy that at least we have identified a new piece of information," says Wamachi