A bite from a tsetse fly is an extremely unpleasant experience. It is not like a mosquito, which can furrow its thin mouthpart directly into your blood, often without you noticing. In contrast, the tsetse fly’s mouth has tiny serrations on it that saw into your skin on its way to suck out your blood.

To make matters worse, several species of tsetse fly can transmit diseases. One of the most dangerous is a parasite that causes “sleeping sickness”, or “human African trypanosomiasis”to give it its official name. Without treatment, an infection is usually fatal.

Like so many tropical diseases, sleeping sickness has often been neglected by pharmaceutical researchers. However, researchers have long endeavoured to understand how it evades our bodies’ defence mechanisms. Some of their insights could now help us eliminate sleeping sickness altogether.

There are two closely-related single-celled parasites that cause this deathly sleep: Trypanosoma brucei rhodesiense and T. b. gambiense. The latter is far more prevalent: it is responsible for up to 95% of cases, mostly in western Africa. It takes several years to kill a person, while T. b. rhodesiense can cause death within months. There are still other forms that infect livestock.

Read more