Does malaria make you smell more attractive to mosquitoes?

Malaria parasites could change the way people smell and make them more enticing to mosquitoes, according to the findings of new research published in the journal Proceedings of the National Academy of Sciences.

Scientists based at the Swiss Federal Institute of Technology and Pennsylvania State University in the US analysed the odour of mice with and without malaria for a period of 45 days.

To their amazement, the scientists discovered that the scent of the infected mice was significantly different to the mice without the malaria parasite.

The infected mice did not have a completely different odour, however the level of compounds already in the mouse odour was altered.

This was more obvious in the mice that were still infectious but not displaying any symptoms of malaria – an important stage of the parasite’s life cycle.

Professor Consuelo De Moraes of Pennsylvania State University and one of the lead authors involved in the research said: “There appears to be an overall elevation of several compounds that are attractive to mosquitoes.”

The researchers say it is likely that infected people smell more attractive but do not have any highly specific body odours, especially as the malaria pathogen can actually have bad effects for the mosquitoes themselves.

“Since mosquitoes probably don’t benefit from feeding on infected people, it may make sense for the pathogen to exaggerate existing odour cues that the insects are already using for host location,” said study leader Professor Mark Mescher.

Most interesting of all was perhaps that the researchers found that the mice that had been infected seemed to have an alteration in body odour – permanently.

Despite these mice no longer showing any signs of the disease, tests on body odour proved they were carriers of the pathogen.

Those involved in study think it is high probable that there is a similar effect in humans and are now recruiting volunteers in Africa to determine if this is indeed correct.

Professor Mark Mescher told the BBC: “One of the major potential values of this research is if it can help us identify people who do not show symptoms of the disease. Without symptoms people carry the disease without treatment and still transmit it.

“But there is still a long way to go. In mice we have a very controlled environment. In humans there are so many different factors at play – from diverse environments to diverse genes.”

As well as hoping to advance methods of preventing malaria transmission by mosquitoes, researchers also hope to find ways of creating non-invasive diagnostic procedures that would enable the efficient screening of populations for the malaria infection, which would find those who don’t necessarily display malaria symptoms but are still able to spread the disease.