News: Using Nature to Combat Malaria

Kenyan researchers combating malaria using nature


In over one hundred countries around the world 400 million people are diagnosed with malaria each year [1]. One million, particularly children under the age of five, are killed by this preventable and treatable blood disease [2]. Researcher Anandasankar Ray in Nairobi, Kenya at the International Centre for Insect Ecology and Physiology (ICIPE) has found natural molecules that could prevent malaria-infected Anopheles mosquitoes from locating humans and injecting parasites into human bloodstreams [3].


Mosquitoes locate and target human beings by detecting carbon dioxide released through the pores of the skin and the exhalation of CO2 .  In partnership with the University of California, Kenyan researchers have identified three molecules that can disrupt the mosquitoes’ odour receptors critical in identifying human flesh. The discovery was made after they observed similar behaviour in fruit flies with comparable attraction to ripe fruit that emit CO, however they also saw that certain molecules emitted by ripened fruits blocked fruit flies entirely [3].


The effectiveness of using these molecules was proven when researchers released mosquitoes that had prior exposure to these molecules in a wind tunnel, after which they noted that the insects got lost along the way. The second test they conducted consisted of releasing mosquitoes in a large enclosure at the Nairobi-based ICIPE. The huts within the enclosure contained either attractive carbon dioxide or carbon dioxide infused with the new molecules. The next day, they found that huts infused with the newly discovered molecules only had half the number of mosquitoes [3]. Since the 50s and 60s when sprays were used profusely mosquitoes have developed survival instincts that make them less likely to fly indoors and more likely to wait for their pray outdoors [4]. However, these molecule disruptors can mask an entire outdoor area, such as the backyard, from mosquitoes.

Ray insists that “[The chemicals] are simple molecules that are inexpensive to purchase.” Instead of conventional, more expensive repellents, they come from sources such as fruits and leaves. If synthesised in a laboratory they could be developed for commercial uses affordable to poor populations around the country. He has already begun working with a US-based company to put his findings into possible household uses [3].


Earlier in the year, Dr. Richard Mukabana at the same research facility endeavored to develop an affordable solution of producing carbon dioxide to ward off mosquitoes. He found that by mixing yeast, sugar and water, the end product released an abundant amount of carbon dioxide. In addition to this mixture he added an unusual ingredient that caught the headlines in the local paper: worn nylon socks. He noted that, [a]fter a mosquito gets in your vicinity, the insect almost always goes for your feet,” because human feet produce “volatile compounds which contain some complicated carboxylic acids” that attract malaria-prone species. He tested his findings in semi-field trials—“enclosed simulations of natural mosquito ecosystems”—and found that the mixture of carbon dioxide from fermentation with worn socks caught 80% of the mosquitoes released [4].