Malaria is spread by mosquitoes, which bite an infected person or animal, then spread the parasite to another human or animal. A new study finds that the parasite that causes the disease produces an odor which attracts mosquitoes, inviting more bites and infections.
The finding that chemical compounds called terpenes give off odors that mosquitoes find inviting could help break the cycle of malaria transmission by leading to a quick, non-invasive test for the disease, which now involves taking a blood sample and looking for evidence of the parasite.
The scent of terpenes is emitted in the breath and sweat of infected individuals.
Audrey Odom is a pediatrician and microbiologist at Washington University School of Medicine in St. Louis, Missouri.
She says her team's work documented that the type of mosquitoes that transmit malaria are able to detect the specific compounds produced by the parasites, an ability that guides the insects to infected people, increasing the chances the disease will spread.
"Do they really do what we think they are doing in terms of promoting malaria transmission? And so we are doing studies to find out what proteins in the malaria parasites produce these compounds," said Odom.
Odom and her colleagues are planning to conduct a clinical trial in Malawi involving children with uncomplicated malaria, to see whether researchers can detect the presence of terpenes in the youngsters' breath and sweat. The measurements will be compared to hospitalized children who do not have malaria.
If the theory holds up - that parasites that infect human blood cells give off a scent that's attractive to mosquitoes - investigators could develop methods for breaking the infection cycle with mosquito traps.
"Other people have already started to try what's called attractive sugar-baiting. So, essentially making traps for mosquitoes that use the kind of compounds that they are attracted to. So, the mosquitoes fly to the traps excited by the smells that they smell and then they get poisoned there," she said.
The study on terpenes is published online in the journal mBio.
The World Health Organization reports malaria infects an estimated 2 million people every year, resulting in almost 600,000 deaths, most of them children under the age of 5.