Malaria Parasite Alters Body Odour of Mice to Attract Mosquitoes

A mosquito feeding on human blood; photo by the CDC

Researchers have discovered that the malaria parasite has a very useful technique to help it complete its lifecycle, at least in mice. The parasite alters the body odour of a mouse, making the animal more attractive to the mosquitoes that the parasite needs for the next stage of its life cycle.

Malaria parasites belong to the genus Plasmodium and are microscopic, single-celled protozoans. The genus affects other mammals, birds and reptiles as well as humans. Five species of Plasmodium are known to cause malaria in humans. As in humans, the malaria parasite that infects mice needs two hosts to complete its complex life cycle - a mouse and a mosquito.

The research concerning Plasmodium and body odour was performed by scientists from Pennsylvania State University and ETH Zurich. The researchers used both infected and uninfected mice in their investigation, which lasted for 45 days. They found that the infected mice emitted a unique ratio of odiferous chemicals from their body compared to the uninfected mice. The identity of the chemicals didn't change, but their ratio did. The change was especially noticeable when the infected mice were showing no symptoms of the infection. This was the critical stage when the malaria parasite needed to enter a mosquito in order to continue its life cycle.

Stages of the life cycle of Plasmodium, stained;
photo by the CDC

The assumption is that the presence of the malaria parasite is somehow responsible for the altered body odour produced by a mouse, but how this happens isn't yet known. It would be very interesting to discover the mechanism involved!

The researchers don't yet know if malaria parasites can alter our body odour, too, but they plan to investigate this. They say that if our odour does change, the alteration could be detected and used as a non-invasive test to identify people who have apparently recovered from malaria but are still infectious. These people could then be treated for the disease.

Malaria is a very unpleasant illness and can be deadly. It's a major problem in some countries. Any method to help reduce its spread would be useful.