A microbe prevents mosquitoes from harboring the malaria parasite

According to the World Health Organization (WHO) The number of people suffering from malaria is increasing. Specifically, it is estimated that there will be 249 million malaria cases worldwide in 2022: 5 million more than in 2021 and 16 million above the pre-pandemic level of 233 million in 2019.

In addition to the disruption caused by Covid-19, the global response to this disease faces a growing number of threats, such as: Resistance to drugs and insecticideshumanitarian crises, scarcity of resources or the effects of climate change.

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

The use of microorganisms to control mosquito-borne diseases has been used previously. However, most methods block the development of parasites of this genus Plasmodium The pathogens that cause malaria, which are transmitted by various species of mosquitoes, are based on genetically modified bacteria.

A new study recently published in the journal Sciencepresents the bacteria Delftia tsuruhatensiswhich occurs naturally in the environment, as an inhibitor against the malaria parasite.

The authors, including a researcher from the Carlos III University of Madrid (UC3M), came across the microbe by chance after noticing that it was a mosquito colony that they were using in GlaxoSmithKline's (GSK) research to develop new drugs were becoming increasingly difficult to infect with Plasmodium.

They then discovered that all of the samples contained a strain of bacteria called Delftia tsuruhatensis TC1who discovered that it slows the growth of Plasmodium in the mosquito's gut, where the parasite develops before migrating to the insect's salivary glands.

Control malaria transmission

Subsequently, experiments with rodents carried out at Johns Hopkins University (USA) showed that this interruption in the growth of Plasmodium led to a reduction in transmission: only a third of mice bitten by mosquitoes carrying these bacteria were infected , compared to 100%. of mice that were bitten by mosquitoes and were not recolonized with the bacteria.

In addition, they found that mosquitoes only need to eat a few bacteria to become colonized, and that once the bacteria are inside the insect, they remain there and continually block the parasite's development.

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

According to the results of the current study, this bacterium can actually reduce the parasite burden in mosquitoes by up to 73%, thanks to the production of a molecule called harmane, which is also found in some plants in traditional medicine cultures.

“The identification of a bacterium that prevents the development of the parasitic phases that occur in mosquitoes without affecting them represents a novel approach in which the likelihood of resistance development is very low since it does not pose any harm to the insects,” explains Alfonso. Mendoza Losana, from UC3M and initiator of the project at GSK. “In addition, it is a non-genetically modified bacterium, which allows for rapid introduction into the field.”