Study shows parasite infection affects circadian clocks

What is the most common night time behavior for humans? Sleep. Imagine one day that the period of time that you sleep at night shortens by five minutes. At first, you wouldn’t notice, but quickly you would find that you always fall asleep during the day. Eventually while this pattern continues, your sleep pattern will have switched, in other words your “day” would be at night, and your “night” will be during the day. That is one of the hallmark symptoms of African Sleeping Sickness caused by the parasite, Trypanosoma brucei.

Sleep is an essential behavior for all mammals, and is controlled by a bundle of cells in the hypothalamus called the suprachiasmatic nucleus (SCN). The SCN receives information about light from your eyes, which is used to synchronize the master cellular clock that governs sleeping patterns, temperature regulation, and the endocrine system. A recent paper (Sleeping sickness is a circadian disorder) published in Nature Communications show that infections of T. brucei in mice cause similar consequences that have only been reported when there are mutations to the clock genes that control the master cellular clock, hence the name. This is important research because it can be critical for patients who have trouble managing the side effects of the arsenic-based treatments, reduce the duration and dosage of current treatments, and maximizing their administration.

This study adds to the rather odd list of questions that researchers who study T. brucei are still struggling to answer after the discovery of the parasite in human blood over 100 years ago (1901 to be exact by Robert Michael Forde). This informal list includes a lack of understanding on how the parasite is able to pass the blood-brain barrier, why secrete extracellular vesicles, the reason for the apparent quorum sensing system in the parasite etc. These questions are not easy nor can they be answered by one driven scientists. The old saying is that it takes a village, however as T. brucei infections are list as a Neglected tropical disease, it looks like that village is missing like the lost colony of Roanoke.

1. Steverding, D. (2008) The history of African trypanosomiasis. Parasites & Vectors 1, 3
2. Rijo-Ferreira, F., Carvalho, T., Afonso, C., Sanches-Vaz, M., Costa, R., Figueiredo, L., and Takahashi, J. (2018) Sleeping sickness is a circadian disorder. Nature Communications 9

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