Is placental malaria a long term risk factor for mild malaria attack in infancy? Revisiting a paradigm

Abstract

Background

Children born to mothers with placental malaria (PM) have been described as more susceptible to the occurrence of a first malaria infection. However, whether or not these children remain more at risk during infancy has never been explored. We aimed to determine if children born to mothers with PM are more susceptible to malaria and remain at higher risk between birth and 18 months.

Methods

550 children were weekly followed-up with control of temperature and, if >37.5°, both a Rapid Diagnosis Test for malaria and a thick blood smear were performed. Taking into account environmental risk of infection, the relationship between occurrences of malaria attacks from birth to 18 months was modeled using Cox models for recurrent events.

Results

PM is not associated with an overall susceptibility to malaria but only with the delay of occurrence of the first malaria attack. Children born from mothers with PM tend to have an increased risk for the first malaria attack (HR=1.33; p=0.048) but not for subsequent ones (HR=0.9; p=0.46). Children that experienced one malaria attack were strongly at risk to develop subsequent infections independently of placental infection and of environmental exposure.

Conclusion

These results are consistent with the existence of an individual susceptibility to malaria that is not related to placental malaria. From a public health point of view, protecting children born to infected placenta remains a priority, but it seems insufficient to account for other frail children for whom a biomarker of frailty needs to be found.