Current estimates of malaria basic reproduction number underestimate parasite transmission efficiency due to multiple blood feeding

Background: Despite significant control efforts based on the large-scale distribution of insecticide treated nets, malaria cases have not declined in recent years. Mathematical models are used to predict the impact of these and other control interventions, but complex mosquito behaviors—such as repeated blood feedings—are generally not incorporated. Here, we examine how malaria transmission dynamics are impacted when infected mosquitoes feed a second time, as is typical in natural field settings. Methods: We performed sporozoite time course analyses to measure the Plasmodium falciparum extrinsic incubation period (EIP) in Anopheles gambiae females blood fed once or twice. We incorporated these findings into a model of the basic reproduction number R0, a measure of transmission potential, using current population and monthly mean temperature data across sub-Saharan Africa. Findings: A second blood feed drastically shortens the EIP and increases the average R0 by 12.2% (range: 10.2%-56.5%), impacting hundreds of millions of people. Moreover, parasite growth is further accelerated in mosquitoes with reduced reproductive capacity, which mimic genetic modifications currently proposed in population suppression gene drives. Interpretation: Our findings suggest that transmission efficiency is systematically underestimated in malaria models, particularly in elimination settings. Due to a shorter EIP, younger mosquitoes and mosquitoes with reduced reproductive ability may provide a larger contribution to infection, with important consequences for insecticide-based interventions and gene drive strategies. These findings call for …