Malaria-infected mosquitoes more enticed by human odour

Malaria-carrying mosquitoes are more drawn to human scent compared with mosquitoes that do not carry the parasite, suggests the findings of a new study.

For the study, led by Dr James Logan of the London School of Hygiene and Tropical Medicine, mosquitoes carrying the malaria parasite Plasmodium falciparum were exposed to nylon socks that had been worn by one of the study authors (Renate Smallegange from Wageningen University in the Netherlands) for about 20 hours previously.

Ms Smallegange state the socks were used as ‘bait’ for the 176 mosquitoes that were analysed in the laboratory. She says: “Volatiles emitted by human feet are known to be highly attractive to Anopheles gambiae females.”

It was estimated that the infected mosquitoes were approximately three times more likely to land and try and bite on the worn socks compared to the mosquitoes without any parasite. For study purposes, the species of mosquito analysed was the Anopheles gambiae – the cause of high transmission rates of malaria in Africa. Both infected and healthier mosquitoes were not particularly keen on unworn socks that were also tested.

Experts are already aware that Anopheles gambiae mosquitoes have certain odour receptors which are effective at picking out specific human scents. The scientists involved in the study are convinced that it is the parasites which are creating a heightened craving for human smells, ergo increasing a risk of UK holiday makers being bitten in the dangerous areas for malaria.

Dr Logan was interviewed by BBC News and explained the findings in the study, commenting: “We think the parasite is giving them a heightened sense of smell. We are hypothesizing there is an alteration somewhere in their olfactory system that allows them to find us quicker,” which would make it more likely that the parasite enters the blood stream, ensuring its survival and the spread of the disease.”

The researchers conclude they are unsure how precisely the parasite alters mosquitoes’ sense of smell, in addition to which component(s) of human odour is the most is deemed most appealing to the mosquitoes as human skin emits over 350 different odour molecules. If this information could be attained from future studies, effective traps could be devised to catch the infected mosquitoes and hopefully lessen the risk of a disease that infects around 200,000 million people around the world each year, killing over 600,000.

If you are about to travel abroad and are unsure of what potential health risks there are or which medications are suitable for your area of travel, Medical Specialists Pharmacy recommend visiting the NHS Fit For Travel website.

Here you can click onto the continent and country you are about to travel to, see a highly detailed list of preventative measures to take before and during travel, what diseases are prominent in that particular country as well as a list of the symptoms of each, and also what medications/immunisations are advisable – i.e. Malarone, Paludrine and Doxycycline are all prescription medications to prevent malaria, with Malarone also able to treat the disease if you contract it. All three are available now from the Medical Specialists Holiday and Travel area of the website, where you can also find treatments for the prevention and control of travel sickness; Kwells, Kwells Kids and Avomine.