Transmission and immunity: the importance of heterogeneity in the fight against malaria

The complex relationship between transmission and parasite prevalence in humans is an important issue. Using a large dataset matching estimates of malaria transmission and Plasmodium falciparum prevalence in African children, a stimulating study published in Nature provides evidence that heterogeneity in susceptibility crucially determines the prevalence of infection. Moreover, it suggests that children who clear infections are not immune to new infections, irrespective of the amount of transmission. It is important to question the relevance of such results based on mathematical models when discussing host–parasite interactions, especially their implications for public health interventions.