Using Bacteria to Prevent the Spread of Malaria

Scientists at Michigan State University have devised a novel strategy that could curtail the spread of one of the world’s most deadly infectious diseases – malaria.

Malaria is a vector-borne parasitic disease caused by protozoa of the Plasmodium family. Transmitted to humans by female Anopheles mosquitoes, malaria is widespread in tropical and subtropical areas, particularly in sub-Saharan Africa. The World Health Organization estimates that 216 million people worldwide contracted malaria in 2010, and that the disease claimed more than 650,000 lives.

Although a range of archaic drugs can be used to prevent and treat this condition, their use in regions where malaria is endemic is limited by their prohibitive cost. Furthermore, attempts to produce an effective human vaccine have proved frustrating, although Professor Adrian Hill’s ongoing work in Oxford holds a great deal of promise.

The researchers, led by Dr Zhiyong Xi, demonstrated that a strain of the bacterium Wolbachia (carried and transmitted by female mosquitoes) can prevent transmission of the malaria parasite from insects to humans. The possibility of “vaccinating” mosquitoes against the malaria parasite has been extensively discussed in the past 20 years, but this study is the first to provide conclusive evidence that it is possible to stably induce infection in large groups.

The wAlbB Wolbachia strain was injected into thousands of Anopheles mosquito embryos; a single infected female was isolated and subsequently bred. The rate of infection in organisms belonging to this mosquito line was 100% after 34 generations. Subsequently, the group demonstrated that the introduction of Wolbachia-infected females into naive, uninfected populations resulted in complete carriage of the infection by all members of a mosquito group within eight generations.

Whilst this technique would represent a cost-effective and efficient method of reducing malaria transmission, it remains to be seen if it can be applied in a broader sense.