An imitation foot odour is the latest eradication measure to be used in the fight against malaria, the deadliest of all tropical diseases. The more weapons employed against the malaria mosquito at the same time, the greater the chance of success.

The good news is that these artificial odour substances really work. But it was also discovered that malaria mosquitoes still find real sweaty feet more attractive than the artificial stuff. It was already known that the mosquitoes are attracted by feet and the smell from feet. So, a group of scientists from the central Netherlands University of Wageningen – which specialises in life sciences – decided to investigate further.

Penetrating odour
The scientists from Wageningen set about trying to identify the chemical components that give sweaty feet their distinctive smell. The idea behind the experiment was to create an imitation aroma mixture to divert the malaria mosquito away from the bedroom at night when most of the bites take place.

The researchers decided not to include real smelly socks - fresh from human stinky feet – in their field experiments, as Africans don’t normally wear socks because of the warm weather. And besides all the practical reasons for not using real socks, certain people seem to attract mosquitoes much more than others. Likewise for their socks. What the scientists are aiming to do is to create a standard aroma sock trap, produce it in large quantities and distribute it at an affordable price.

Foot odour is made up of a mixture of fatty acids, ammonia and lactic acids. Postdoctoral researcher Doctor Renate Smallegange came up with the idea of mixing these substances:

“I decided to combine these substances in one mixture. The results of the experiment showed that this mixture was very attractive to the mosquito, much more so than the components individually. The next question to investigate was how effective it is when compared to odour from human sweat.”

Warning system
Dr Smallegange concluded that, when given a choice, mosquitoes go for real smelly feet. But her research can still be put to good use. Field experiments in Africa showed that by hanging the imitation odour traps outdoors, many mosquitoes were diverted. The traps can also serve as a kind of warning system – if they’re regularly full,  the local population then knows that they have to use other eradication measures.

Wageningen University’s young scientist believes adamantly in implementing parallel measures simultaneously.

“We know that the use of mosquito nets offers very good protection, but we also know that it isn’t enough. We have to apply several modes. We have to continue using chemical and biological methods, we have to try to kill more mosquito larvae, but we also have to make the use of traps to lure mosquitoes widespread.”

The ideal smelly sock perfume
Placing the imitation foot odour substance in a trap outdoors and hanging it in a tree, for instance, can make a considerable difference. Dr Smallegange is now going to focus the research on finding the ideal “smelly sock perfume”. The researcher is still short of some essential stuff which is found in the human aroma profile. She doesn’t know yet what these aroma substances are, but will make some selections to find out which of them can be perceived by the mosquito in the hope of finding that one substance that will combat the malaria mosquito.

Listen to mosquito chorus