The microbe prevents mosquitoes from carrying the malaria parasite

This discovery could provide an additional weapon against the spread of malaria around the world.

Estimated reading time: 5 minutes

Fountain: UC3M

Rights: Creative Commons.

According to the World Health Organization (WHO), The number of malaria cases is growing. In particular, it is calculated that There were 249 million cases of malaria reported worldwide in 2022: 5 million more than in 2021 and 16 million above the pre-pandemic level of 233 million reported in 2019.

In addition to the disruptions caused by Covid-19, the global response to the disease faces a growing number of threats, such as resistance to drugs and insecticideshumanitarian crises, resource constraints or the effects of climate change.

More than half a million people die every year Because of this disease, the majority are children under 5 years of age. Although some vaccines have been developed, their effectiveness is limited and they are still in the early stages of introduction in Africa.

The use of microorganisms to control mosquito-borne diseases has been used in the past. However, most methods of blocking the development of parasites of the genus Plasmodium which cause malaria, transmitted by various types of mosquitoes, are based on genetically modified bacteria.

A new study recently published in the journal The sciencerepresents bacteria Delftia tsuruhatensisnaturally present in the environment as an inhibitor of the malaria parasite.

The authors, including a researcher from the Carlos III University of Madrid (UC3M), stumbled upon the microbe by accident after noticing that a colony of mosquitoes they were using in GlaxoSmithKline (GSK) research to develop new drugs was becoming increasingly difficult to become infected with Plasmodium.

They subsequently confirmed that all samples contained a bacterial strain called Delftia tsuruhatensis TC1who found that it slowed the growth of Plasmodium in the mosquito’s gut, where the parasite develops before moving into the insect’s salivary glands.

Combating malaria transmission

Subsequently, experiments on rodents carried out at Johns Hopkins University (USA) showed that this cessation of Plasmodium growth led to a decrease in transmission: only a third of mice bitten by mosquitoes carrying these bacteria became infected, compared with 100%. mice bitten by mosquitoes that are not colonized with bacteria.

Moreover, they discovered that mosquitoes only need to eat a few bacteria to colonize, and that once inside the insect, the bacteria remain there, permanently blocking the development of the parasite.

Field studies in Burkina Faso and modeling have shown that Delftia tsuruhatensis TC1 has the potential to complement the control of malaria transmission.

In fact, according to a recent study, these bacteria can reduce the parasite load of mosquitoes by up to 73% by producing a molecule called harmane, which is also found in plants used in traditional medicine in some countries. culture.

“Identifying bacteria that prevent the development of parasitic phases that occur in mosquitoes without affecting them represents a new approach with very little chance of resistance developing since it does not cause any harm to the insects,” he explains to Alfonso. Mendoza Lozana from UC3M and project initiator at GSK. “In addition, these are non-genetically modified bacteria, which allows them to be quickly introduced into field studies.”

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