The malaria parasite can "lurk" in the bloodstream for months

Source: Science and Technology Daily

Altered gene expression avoids the immune system Plasmodium can "lurk" in the bloodstream for months

Plasmodium falciparum is the most important parasite that causes malaria. A medical study published in the British journal Nature Medicine on the 27th found that this malaria parasite can remain in human blood during the dry season by changing its gene expression, while not causing disease. The findings explain how Plasmodium falciparum remains in the human body without causing visible symptoms, and when mosquito populations make a comeback during the rainy season, they become "internal lurkers" for malaria to spread again.

Globally, malaria kills an average of 1,200 people a day – a major lethal disease in Africa, claiming 400,000 lives in 2018, the vast majority of them children under the age of 5.

Malaria morbidity and mortality have declined significantly through the use of insecticide interventions, but rising resistance to insecticides in mosquito populations, combined with other adaptive changes, could allow these gains to be reversed. The majority of malaria cases are concentrated during the rainy season, when mosquitoes that transmit Plasmodium falciparum multiply in large numbers. However, asymptomatic infected people can occur all year round, and the ability of the malaria parasite to reside in the human host allows them to survive the months-long dry period between the rainy seasons. However, scientists have been unable to understand for years why the parasite can inhabit a human host without causing visible symptoms.

Between 2017 and 2018, Selvia Potogle, a scientist at the Max Planck Institute for Infection Biology in Germany, and colleagues tracked 600 Malian residents ranging in age from 3 months to 45 years. They found that the genetic transcription patterns of Plasmodium falciparum in these populations near the end of the dry season were unique. This pattern is associated with decreased vascular adhesion of infected red blood cells, which facilitates the spleen to clear infected blood cells to lower levels.

In their findings, the researchers said these traits help maintain low levels of Plasmodium falciparum "reservoirs" in the human body that can be undetected and cleared by the immune system, continuing to initiate the cycle of malaria transmission during the subsequent rainy season.

Further research is needed to elucidate how environmental changes affect the transcriptional patterns of Falciparum malaria, but it is now known that this pattern allows Plasmodium falciparum to survive in specific environments, laying the groundwork for humans to eventually conquer the disease.

Editor-in-chief dots

During the long years of coexistence with humans, the malaria parasite also developed its own way of lurking. In the trough days, you can raise soldiers and accumulate sharpness, minimize your sense of existence, and exchange for peaceful coexistence with the human immune system. Wait until the right season comes, then get back active, storm the camp, and create a pop. But what exactly is the signal that makes them dormant and active, and how do they perceive it? When they choose to stay still, is there a way to get rid of their nest? Malaria parasites are smart, but so are humans. Magic is a foot tall, and figuring out their behavior patterns can also help conquer malaria. (Reporter Zhang Mengran)