17 May 2013

Malarial mosquitoes like targetting humans

7:29 am on 17 May 2013

Mosquitoes carrying the malaria parasite are far more attracted to humans than those without it.

All mosquitoes are attracted by the smell of human sweat, but researchers in the Netherlands found malarial mosquitoes are three times as likely to be lured towards a human scent.

They believe that the deadly parasites are seizing control of their biting hosts and boosting their sense of smell.

The research is published in the journal Plos One.

"One thing that always surprises me about parasites is how clever they are. They are these ever-evolving organisms that seem to be one step ahead of us the whole time."

To carry out the study, malaria mosquitoes (Anopheles gambiae) were infected with the most deadly form of parasite, Plasmodium falciparum.

The BBC reports about 100 of the infected insects were placed in a container, along with some nylon stockings that had been previously worn by volunteers for 20 hours.

"It is a very effective way of collecting body odour... the odour can remain attractive for months," said Dr James Logan of the London School of Hygiene and Tropical Medicine.

The scientists repeated the experiment with uninfected insects.

They found that mosquitoes carrying the deadly parasite were three times more likely to be attracted to the smelly stockings.

"We think it is giving them a heightened sense of smell,'' said Dr Logan. ''We are hypothesising there is an alteration somewhere in their olfactory system that allows them to find us quicker."

By making humans an easier target, the parasite is more likely to be passed into the blood stream - ensuring its survival and continuing the spread of the disease.