Parasite offence or host defence? The roles of biological rhythms in malaria infection

For several centuries, the species of malaria parasite that infect a patient was diagnosed by the regularity of fever (every one, two, or three days). Fever results from the synchronous bursting of malaria parasites in the host’s blood when they release their progeny to infect new red blood cells and cause the symptoms of malaria. Despite this knowledge, it is unknown why parasites that exclusively live in the bodies of other organisms have a daily rhythm. I have shown that the survival and transmission of malaria parasites depends on the coordination of their developmental rhythm with the circadian rhythm of their host.

I will integrate evolutionary ecology, chronobiology and parasitology to explain how parasite rhythms are generated and why daily rhythms matter for parasite fitness. This will open up novel avenues for disease control which includes the development of drugs to disrupt parasite rhythms, harnessing circadian systems to enhance immune responses, or precisely timing drug administration to make treatment more effective.

Growing evidence that the daily rhythms of malaria parasites can confer tolerance to antimalarial drugs and that the use of bed nets is changing the biting time of the mosquitoes that transmit malaria, makes understanding how and why parasites exhibit daily rhythms increasingly urgent.