Malaria Infection Makes Mosquitoes Crave Humans

Mosquitoes carrying the malaria parasite are more attracted to human body odor than uninfected insects are, suggests a new study out of London, England.

Researchers from the London School of Hygiene and Tropical Medicine have found the parasites inside the infected mosquitoes apparently boosted their hosts' sense of smell --- which resulted in the insects becoming three times more likely to be lured toward a human scent

The research is published in the journal Plos One.

"One thing that always surprises me about parasites is how clever they are," Dr. James Logan, one of the study's primary researchers, was quoted saying by BBC News. "They are these ever-evolving organisms that seem to be one step ahead of us the whole time."

For the study, the researchers infected mosquitoes (Anopheles gambiae) with the most deadly form of malaria parasite, Plasmodium falciparum.

They then placed about 100 of the infected blood-suckers into a container, with some nylon stockings that had been previously worn by volunteers for 20 hours.

Explained Logan about the stockings: "It is a very effective way of collecting body odor... the odor can remain attractive for months."

The scientists repeated the experiment with uninfected insects and determined the mosquitoes carrying the parasite were three times more attracted to the smelly leg apparel.

The research team deduced the parasites change how their mosquito hosts perceive things and leave them with an overriding desire for human contact.

"We are hypothesizing there is an alteration somewhere in their olfactory system that allows them to find us [human targets] quicker," Logan said.

By heightening the chances of human infection, the malaria parasites go a long way in guaranteeing their own survival, as well as the continued the spread of the deadly disease, which, in 2010, infected about 219 million people worldwide and caused 660,000 deaths, according to the World Health Organization.

The researchers will now begin a three-year project, funded by the Biotechnology and Biological Sciences Research Council, to learn more about how the parasites change the preferences of mosquitoes.