Mosquitoes like blood from people infected with malaria

Malaria mosquitoes (Anopheles gambiae) prefer to feed - and feed (and feast) more - on blood from people infected with malaria. Researchers have now discovered why[1].

The malaria parasite Plasmodium falciparum produces a molecule, HMBPP, which stimulates the human red blood cells to release more carbon dioxide and volatile compounds, such as monoterpenes[2]. Together they produce an irresistible smell to malaria mosquitoes. The mosquitoes also eat more blood. Ingrid Faye and her colleagues discovered that most malaria mosquitoes were attracted by HMBPP-blood, even at very low concentrations. The mosquitoes are also attracted more quickly and drink more blood.

Moreover, these mosquitoes acquire a more severe malaria infection, which means that higher numbers of parasites are produced. This indicates that the extra nutrients from the larger meal of blood are used to produce more parasites, researchers believe. Neither humans nor mosquitoes use HMBPP themselves, but the parasite needs the substance to be able to grow."HMBPP is a way for the malaria parasite to hail a cab, a mosquito, and successfully transfer to the next host", Noushin Emami explains. She has worked over three years in the project.

"This seems to be a well-functioning system, that evolved over millions of years, which means that the malaria parasite can survive and spread to more people without killing the hosts", says Faye.

These results may be useful in combatting malaria. Today the most efficient way is to use mosquito nets and insecticides to prevent people from being bitten. Increasing resistance against the insecticides require new control methods to be developed to tackle the mosquitoes. In addition, medicines become progressively inefficient when the parasite becomes resistant to them and new drugs must be developed constantly.

A vaccine seems far away. Faye thinks that a major step forward in the fight against malaria would be to create a trap that uses the parasite's own system for attracting malaria mosquitoes.

[1] Noushin Emami et al: A key malaria metabolite modulates vector blood seeking, feeding, and susceptibility to infection in Science – 2017
[2] Lindberg et al: Immunogenic and Antioxidant Effects of a Pathogen-Associated Prenyl Pyrophosphate in Anopheles gambiae in PloS One – 2013