Smelly feet linked to malaria risk

29 Dec 2011, 5:56 pm   -   Source: AAP
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Mosquitoes that spread the disease are attracted to people whose feet are heavily covered with certain kinds of bacteria. (AAP)

Mosquitoes that spread the disease are attracted to people whose feet are heavily covered with certain kinds of bacteria. (AAP)

Smelly feet may be one of the answers as to why malaria carrying mosquitoes find humans irresistible to bite, says a new study from a Dutch university.

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Smelly feet may be a serious health hazard in parts of the world affected by malaria, new research suggests.

Mosquitoes that spread the disease are attracted to people whose feet are heavily covered with certain kinds of bacteria, scientists have discovered.

The bugs give off an odour that draw the insects in, thereby increasing the chances of being bitten.

However individuals with many different kinds of bacteria on their feet seem to have some protection.

This may be because they carry specific microbe smells that deter the mosquitoes, scientists believe.

The findings, published in the online journal Public Library of Science ONE, could lead to new ways of preventing malaria and other insect-spread diseases by altering body odour.

Authors Dr Niels Verhulst, from Wageningen University in the Netherlands, and colleagues wrote: "Compounds that inhibit microbial production of human odour, or manipulation of the composition of the skin microbiota may reduce a person's attractiveness to mosquitoes."

The researchers sampled sweat from the soles of the feet of 48 mostly Caucasian male volunteers aged 20 to 64.

Feet odour in particular is known to be attractive to the malaria-carrying mosquito Anopheles gambiae.

Before the start of the study participants were told to refrain from drinking alcohol, eating garlic, onions or spicy food, taking a shower or using perfumed cosmetics.

They were also told to wear special nylon socks provided by the research team for 24 hours before sampling.

"Volunteers were instructed not to use soap since the last time they showered before the experiment," the scientists wrote.

In a series of experiments, the researchers tested the attractiveness of different samples to A. gambiae mosquitoes from Liberia, Africa, where malaria is endemic.

Samples from nine volunteers were found to be "highly attractive" to the insects while seven others were "poorly attractive".

The degree to which mosquitoes homed in on the samples depended on the abundance and type of bacteria present. Levels of Staphylococcus were 2.62 times higher in samples from "highly attractive" than from "poorly attractive" individuals.

Three other bacterial types also appeared to attract the insects, while two others, Variovorax and Pseudomonas, had the opposite effect and repelled them.

Samples from people carrying a more diverse range of bacteria were less attractive to the mosquitoes than others with large numbers of specific types.

"The discovery of the connection between skin microbial populations and attractiveness to mosquitoes may lead to the development of new mosquito attractants and personalised methods for protection against vectors of malaria and other infectious diseases," the scientists wrote.

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