How to stop the malaria parasite from infecting millions per year

By Alice Clifford via SWNS

Disorienting the malaria parasite could be a way to stop the infection that hits 250 million people a year, scientists believe.

Malaria is a parasitic disease transmitted by mosquitoes and caused by a microbe of the genus called Plasmodium.

With 621,000 fatal cases annually, malaria remains a major public health problem, particularly in sub-Saharan Africa.

On its journey from mosquito to human, Plasmodium must adapt to the specifics of the many organs and cells in its host.

Microbes do not have sensory organs, instead, they have sensors made of proteins that detect molecules specific to the environments they colonize.

These sensors enable the parasite to know precisely where it is and what to do.

By scrambling these sensors, scientists believe they can confuse the parasite and stop them in their journey as they can’t figure out where they are and what to do.

When a human is bitten by a Plasmodium-infected mosquito, the parasite enters the bloodstream and travels to the liver, where it thrives for around ten days without causing any symptoms.

After this period, Plasmodium re-enters the bloodstream, where it parasitizes red blood cells.

Once inside the red blood cells, the parasites multiply in a synchronized 48-hour cycle.

At the end of each cycle, the newly-formed parasites leave their host red blood cells, destroying them and infecting new ones.

It is this destruction of red blood cells that causes the waves of fever associated with malaria.

Severe forms of malaria are linked to the obstruction of blood vessels by infected red blood cells.

When a mosquito bites a human already infected, the parasite is able to change its development program to colonize the intestine of the mosquito, enabling it to infect a new human.

There are small molecules absent in the blood but present in the mosquito that the parasite is able to detect and then adapt to.

But scientists believe that scrambling the signals that the sensor picks up that tell the parasite to develop for its new host could disorientate it and stop its painful rampage.

Study author Ronja Kühnel, a Ph.D. student at the University of Geneva (UNIGE), said: "Starting from this single known element, we have identified a sensor that enables the parasite to detect the presence of these molecules when it is ingested by a mosquito.

"This sensor is made up of five proteins. In its absence, the parasite does not realize that it has left the bloodstream for the mosquito, and is therefore unable to continue its development".

This sensor is also present at other stages of the parasite lifecycle, notably when the parasite has to leave the red blood cell.

Study author Emma Ganga, another Ph.D. student at the university, said: "We then observe exactly the same mechanism: without this sensor, Plasmodium is trapped in the red blood cells, unable to continue its infection cycle."

But, scientists have not yet identified the human molecules detected by the parasite.

Identifying them could provide a better understanding of how waves of fever are caused by Plasmodium.

Study author Dr. Mathieu Brochet, an associate professor in the Department of Microbiology and Molecular Medicine at the UNIGE Faculty of Medicine, said: "Understanding this very specific biological mechanism is an important step towards countering the parasite.

"At each stage of its life cycle, the parasite must logically pick up signals that enable it to react correctly, but which ones and how?"

The study was published in the journal Science Advances.