Mosquitoes and Malaria: The Risk of Multiple Feeders

Mosquitoes that are drenched in germs -- that is, those which have been doubly exposed to malaria strains -- are more likely to cause humans to be infected repeatedly with the Plasmodium parasite and expose them to multiple infections.

That is, researchers at the University of Edinburgh and U.S. colleagues recently published their findings about why infections reach higher densities when another strain is present, in PLOS Pathogens.

In the research, the scientists allowed female Anopheles mosquitoes at defined times to feed on mice infected with two different Plasmodium strains. They examined how a co-infecting strain affects parasites that enter the mosquito, as a release stated. 

The researchers learned that after feeding on multiple hosts, mosquitoes can gather mixed strain malaria infections. The parasites have a real leg up in establishing a secondary infection if another Plasmodium strain is present in a mosquito. So, doubly infected mosquitoes have substantially higher parasite loads, the release said.

In general, multiply feeding mosquitoes pose a higher risk of spreading drug-resistant strains, scientists said in the release: "By increasing the proportion of infectious mosquitoes with mixed strain infections, it is also likely that the facilitation reported here will increase the rates of mixed infections in vertebrate hosts which could have implications for infection virulence and the spread of drug resistant strains."