Malaria parasites can manipulate the body odour of mice, research in the journal Proceedings of the National Academy of Sciences suggests. Researchers believe parasites may change odours in order to help them with a key stage in their reproduction. And scientists found the altered scent persists at a critical time when mice have no symptoms but remain infectious. They are working on further trials to determine whether parasites can affect human smell too. Scientists from the Swiss Federal Institute of Technology and Pennsylvania State University in the US studied the odour of mice with and without malaria for 45 days. They found the scent of infected mice was markedly different to non-infected ones. The parasite did not completely alter the smell of the individual - instead it changed the level of compounds already present in mouse odour. And this was particularly noticeable in mice which were still infectious but no longer showed any symptoms of the disease - corresponding to a crucial time in the life cycle of the parasite. Prof. Consuelo De Moraes of Pennsylvania State University and one of the lead authors of the research said: “There appears to be an overall elevation of several compounds that are attractive to mosquitoes.” The study showed mosquitoes were most attracted to mice when the parasites in their bodies were at a key point in their development - a stage when they needed to be passed back to a mosquito in order to reproduce. Malaria parasites have a complex life-cycle with several stages. They need to develop and mature in both humans and mosquitoes. Scientists believe parasites may manipulate the host’s smell in order to ensure continued survival. Researchers are now working on trials to see if this pattern of odour change can be traced in humans too. Prof. Mark Mescher of Pennsylvania State University said one of the major potential values of this research is if it can help us identify people who don’t show symptoms of malaria. “Without symptoms people carry the disease without treatment and still transmit it. But there is still a long way to go.
