Mosquitoes infected with the malaria parasite are significantly more attracted to human odors than uninfected mosquitoes.
Researchers already knew that the microscopic parasite - Plasmodium falciparum - can alter the behavior of the mosquitoes it infects, causing them to consume larger and more frequent blood meals. That increases the rate of malaria transmission.
But now James Logan and colleagues at the London School of Hygiene and Tropical Medicine have identified another behavioral change. Using fabric permeated with human odor, they found that "malaria-infectious females are more attracted to human odors than uninfected mosquitoes." They landed on and probed the fabric about three times more frequently than the females that did not carry the parasite. Only female mosquitoes bite.
That finding, reported in the journal PLOS-One, casts doubt on the reliability of earlier malaria transmission studies which typically have used uninfected mosquitoes.
The new study suggests those earlier results may not always be representative of the behavior of infected insects. Logan and his colleagues conclude that understanding the olfactory changes behind the enhanced attraction to humans may help identify new weapons in the fight against this dangerous disease.
Each year, malaria infects more than 200 million people worldwide, and claims an estimated 660,000 lives.