Malaria – Researchers in Lausanne have found that mosquitoes that last sucked the blood of a malaria-infected animal catch the most pathogenic microorganisms. They report that in the magazine “Proceedings B” of the Royal Society.
Malaria is caused by the so-called Plasmodium. This single-celled parasite lodges in red blood cells and destroys them. More than 400,000 people die each year from infectious diseases.
A team led by Philip Christ of the University of Lausanne has now shown that the sequence in which mosquitoes attach to a sick animal affects the spread of the disease.
Super spread among mosquitoes
Field surveys have found that several mosquitoes carry large numbers of malaria parasites. These are, so to speak, super sprayers among insects. However, most of them are almost completely free of pathogenic microorganisms.
The researchers looked at this phenomenon in more detail in the laboratory. To do this, they had healthy mosquitoes that bite canaries that carry the pathogen. Result: Insects swallowed the same number of parasites. But seven days after the blood meal, the mosquitoes that were last bitten were about five to ten times more contaminated with pathogenic microorganisms.
According to researchers, parasites can detect if their host is bitten and then increase their infectivity.
Refine epidemiological models
The researchers hope their study will help develop better strategies to fight the disease. “Malaria transmission is increasing overnight,” said Romain Pigo of the University of Lausanne, according to a statement from the university. “Mosquitoes that end up biting will be much more contagious than those that attack in the dark.” That is why mosquito nets are becoming more and more important as the night progresses.
The authors also propose to consider the observed effects in epidemiological models of malaria spread.