Multiple mosquito blood meals accelerate malaria transmission

Multiple bouts of blood feeding by mosquitoes shorten the incubation period for malaria parasites and increase malaria transmission potential, according to a study published recently in the open-access journal PLOS Pathogens. Given that mosquitoes feed on blood multiple times in natural settings, the results suggest that malaria elimination may be substantially more challenging than suggested by previous experiments, which typically involve a single blood meal.

Malaria remains a devastating disease for tropical and subtropical regions, accounting for an estimated 405,000 deaths and 228 million cases in 2018.

In natural settings, the female Anopheles gambiae mosquito – the major malaria vector – feeds on blood multiple times in her lifespan. Such complex behaviour is regularly overlooked when mosquitoes are experimentally infected with malaria parasites, limiting our ability to accurately describe potential effects on transmission.

 The results show that an additional blood feed three days after infection with P. falciparum accelerates the growth of the malaria parasite, thereby shortening the incubation period required before transmission to humans can occur. Incorporating these data into a mathematical model across sub-Saharan Africa reveals that malaria transmission potential is likely higher than previously thought, making disease elimination more difficult.

In addition, parasite growth is accelerated in genetically modified mosquitoes with reduced reproductive capacity, suggesting that control strategies using this approach, to suppress Anopheles populations, may inadvertently favour malaria transmission.

 The findings have important implications for accurately understanding malaria transmission potential and estimating the true impact of current and future mosquito control measures.