Could a chance discovery mean the end of malaria?

The chance discovery occurred when the team noticed that a colony of mosquitoes being used for drug development had stopped carrying malaria and did not develop the parasite that causes it.

The researchers say the bacteria could be a new tool for fighting one of the world's oldest diseases, which kills 600,000 people every year.

The team froze the samples from their 2014 experiment and went back to them two years later to explore what had happened.

Here they discovered that a specific strain of bacteria - TC1 - which is naturally present in the environment had stopped the development of the malaria parasites in the mosquitoes’ guts.

The data, published in Science magazine, suggests the bacteria can reduce a mosquito's parasite load by up to 73 per cent.

The bacteria works by secreting a small molecule, known as harmane, which inhibits the early stages of the malaria parasite growing in the mosquito's gut.

In conjunction with Johns Hopkins University, the GSK scientists discovered that harmane can either be ingested orally by the mosquito, if mixed with sugar, or absorbed through its cuticle on contact.

The findings open the possibility of treating surfaces in areas where the insects rest with the active compound.

Trials are now taking place at a contained field research facility called MosquitoSphere in Burkina Faso to assess how effective and safe it would be to use harmane at scale in the real world.

The hope is that, by developing this bacteria-based intervention into a product, scientists may soon have another tool in the box against one of the world's oldest diseases.

Malaria kills about 620,000 people a year - often children under the age of five. Vaccines have now been developed, but they are still in the early stages of being rolled out in Africa.

Related: US health alert over malaria cases