Monsters Inside Mice: Malaria Parasites Rely on Host's Circadian Rhythms

Humans rely on their circadian rhythms for numerous processes and functions, but so do the organisms living within humans. Parasites depend on daily (circadian) rhythms to maximize fitness within their hosts. A host’s circadian rhythms are responsible for the timing of rhythms in parasite development and are a crucial component in parasite replication. A better understanding of the regulation of parasites’ rhythms and their effect on fitness could dramatically influence the severity and circulation of numerous parasitic diseases. 

In this study, the researchers analyzed how hosts’ circadian rhythms affected the replication of malaria parasites in mice. They disturbed the normal feeding patterns of mice by 12 hours to “desynchronize the host’s peripheral oscillators from the central, light-entrained oscillator in the brain and their rhythmic outputs” (Prior et. al, 2018). This caused the malaria parasites to have an inverted circadian rhythm within mice fed during the day compared to mice fed at night. 

Their results found that the mice’s feeding times and metabolisms determined the parasites’ rhythms more significantly than the time of day. The parasite rhythms were also found to depend on the hosts’ blood glucose levels. Their research asserts that the malaria parasites actively control their own developmental rhythms based on the hosts’ feeding time and dynamic circadian rhythm. 

This research in host-parasite-vector coevolution has various implications in areas of bioscience, pathology, microbiology, and more. This research is particularly revealing of many parasites’ abilities to employ effective strategies within hosts, even adapting to their host’s circadian rhythm, to enhance their survival and reproductive efficacy. Perhaps, future studies and medical treatments could find a way to exploit this unique relationship between hosts and parasites to effectively reduce the severity and transmission of parasitic diseases, including malaria, which is a leading cause of death and disease in many countries.

Prior, K. F., Veen, D. R., O’Donnell, A. J., Cumnock, K., Schneider, D., Pain, A., . . . Reece, S. E. (2018, February). Retrieved from 

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5843352/