More than 400,000 people are killed by malaria each year, most of them children under the age of five. Malaria is spread by the bite of infected mosquitoes.

The newly discovered microbe, Microsporidia MB, protects mosquitos from being infected, which could in turn protect people.

The discovery was made at Lake Victoria in Kenya. The researchers could not find mosquitos who carried the Microsporidia and also had the malaria parasite. Lab experiments confirmed the microbe protected the mosquitos from the parasite.

Dr Jeremy Herren at the International Centre of Insect Physiology and Ecology said: "The data we have so far suggest it is 100-per-cent blockage, it's a very severe blockage of malaria. I think people will find that a real big breakthrough."

It is still not entirely clear how the microbe stops malaria, but researchers think it primes the mosquito’s immune system so it can fight off infections easier. Another theory is that the microbe makes the mosquito’s metabolism inhospitable for the malaria parasite.

Now, researchers plan to infect mosquitos with Microsporidia in order to fight the malaria parasite. About 40 per cent of mosquitos in a region need to be infected with the microbe to significantly reduce malaria.

The researchers are investigating two main strategies: they could release Microsporidia to infect mosquitos or infect male mosquitos in the lab and let them infect females when they have sex.

"Further studies will be needed to determine precisely how Microsporidia MB could be used to control malaria”, said Herren. “The next phase of the research will investigate Microsporidia MB dynamics in large mosquito populations in screen house 'semi-field' facilities.”