Is it better to encounter a microbe in the morning, the afternoon or the evening? The day or the night? A new study conducted at McGill university in Montreal shows that the time at which one is infected is not indifferent to the severity of evil (work published in Scientific Reports)
The team led by professor Nicolas Cermakian is interested in leishmaniasis. This disease affects humans and many other mammals, including the dog, who is very sensitive.
It is expressed either on the skin or in the viscera. It is due to protozoa mobile, single cells more complex than bacteria, of the genus Leishmania of the family Trypanosomatidae. It is transmitted by the bite of females of some species of mosquitoes, especially in the evening. Each year it infects over a million people per year worldwide, mainly in tropical areas.
It causes each year many thousands of deaths and leaves many of the sequelae to the people who have been cured. this is the first time that such a phenomenon is evidence for a parasite transmitted by a mosquito vector. Canadian researchers have injected to mice-models to the parasite. And then have measured both the immune response of infected individuals and the speed of invasion of the parasites. They were able to see that these two parameters varied a lot in function of the time at which the infection was triggered.
“Our previous studies had shown that our immune system has a own biological clock,” explains Nicolas Cermakian. Our mechanisms of defense against microbes are more or less active at different times of the day. “Oddly, the infection to the parasites is the most effective in the end of the day, early evening, whereas this is precisely the time when the immune system is more active and strong.
The researchers believe that the parasite will thrive due to the inflammatory process triggered by his arrival with the mobilization of cells such as macrophages and neutrophils, that are supposed to fight, but that the parasite will “return” and use it to his advantage. Researchers at Cambridge university had, last year, demonstrated that the infection due to the herpes virus was also found to be dependent on the biological clock immune. But this is the first time that such a phenomenon is evidence for a parasite transmitted by a mosquito vector. A better understanding of the mechanisms at play may enable the implementation of new modalities of treatment, say the researchers. .