The Mysterious Sleeping Sickness: Your Brain on Protozoans

tsetse fly

When I was a kid, I read a book about African explorers. I was living in Africa at the time, so the story was especially alluring. Africa: home to heartbreakingly beautiful sunsets, the most delicious orange Fanta I’ve ever had, one of the best zip lines in the world, and the greatest number of diseases of any country on earth. The book was about these two men journeying alone into the jungles of what was, at the time, the nation of Zaire (today it is the Democratic People’s Republic of Congo). They had a compass, sleeping bags, enough fresh water for a week, and their wits. Of course, like many adventure stories, the two men didn’t have a peaceful time frolicking amongst the epiphytes. No, they met angry local people, had a run in with a cheetah, ran out of water, and had to build a shelter out of monkey bones. Then, one of them got bitten by a tsetse fly and fell into a strange dreamlike trance. The story was fiction but, as I would soon learn from my dad (a medical student at the time), sleeping sickness is very real, and very frightening. I spent the rest of our year in Kenya scouring my surroundings for tsetse flies so that I might escape the fantasy explorer’s dreaded fate.

African Sleeping Sickness

Sleeping sickness, or African trypanosomiasis, Congo trypanosomiasis, or African lethargy, is a parasitic disease that affects both animals and people (who, of course, are animals, but you understand the distinction). It’s caused by a protozoan, Trypanosoma brucei, and is transmitted by a bite from the tsetse fly. Over the past century there have been a few large epidemics of the illness but today about 50,000 to 70,000 people are thought to be infected worldwide. Infection is treatable but, if left untreated, it causes a round of severe flu like symptoms, giant swollen glands and joint pain. Then, in its secondary stages, the disease crosses the blood-brain barrier, damaging the central nervous system. These are the symptoms the explorer suffered in my book.

protozoa

Stage Two Infection

The neurologically affected patient suffers disruption of his sleep cycle, experiencing severe fatigue followed by manic insomnia. He suffers confusion and reduced coordination. Once the disease has reached this stage it is irreversible and, if left untreated, is always fatal.

Emerging Sleep Science

I’ve been rather obsessed with sleeping sickness ever since I first learned about it and have closely followed new research into the disease. I’ve often wondered if studying how the trypanosomes affect the sleep cycle could help scientists to understand the parts of the brain responsible for maintaining it. Today, scientists believe infection causes swelling, and it’s an inflammatory response in the hypothalamus that may cause the sleep disruptions. The hypothalamus, it turns out, is critical for regulating rest and arousal. It’s also thought to be the emotional center of the brain, which may hint at why sleeplessness is so detrimental to mood. So, avoid the tsetse fly, and enjoy your healthy, cozy night’s sleep. Sorry if I caused you a few nightmares.

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