Sleeping sickness, medically known as African trypanosomiasis, is caused by tiny parasitic organisms called protozoa from the genus *Trypanosoma*. These parasites are transmitted to humans primarily through the bite of an infected tsetse fly, a bloodsucking insect native to sub-Saharan Africa. The disease is not contagious through casual contact between people but depends on this specific vector for transmission.
There are two main types of sleeping sickness based on the subspecies of the parasite involved: *Trypanosoma brucei gambiense* and *Trypanosoma brucei rhodesiense*. The first causes a chronic form mostly found in West and Central Africa, responsible for about 92% of cases. It progresses slowly over months or years. The second type causes a more acute illness in East Africa and develops rapidly after infection.
The tsetse flies that carry these parasites thrive in certain environments such as riverine forests, lakesides, and dense vegetation where they can easily find hosts to feed on. When an infected tsetse fly bites a human to take blood, it injects the parasites into the bloodstream. Once inside the body, these protozoa multiply and spread through various tissues including lymph nodes and eventually reach the central nervous system.
As they invade deeper into neurological tissues like the brain and spinal cord, they cause severe symptoms affecting sleep patterns—hence “sleeping sickness”—along with behavioral changes such as confusion or irritability. Early signs often include fever, headaches, joint pain, fatigue, and swollen lymph nodes near where the bite occurred.
If untreated at this stage or beyond it advances further into neurological involvement causing disrupted sleep cycles (patients may experience daytime drowsiness with nighttime insomnia), personality changes, difficulty concentrating or walking difficulties due to nerve damage. Eventually coma ensues followed by death if no medical intervention occurs.
Transmission does not occur directly from person-to-person contact but can rarely happen via blood transfusions from infected donors or congenitally from mother to fetus during pregnancy when parasites cross placental barriers.
The life cycle of these parasites involves both humans (or other mammals) as hosts where multiplication occurs inside body fluids like blood and lymphatic fluid—and tsetse flies which act as vectors carrying them between hosts after ingesting them during feeding sessions on infected individuals or animals.
In summary:
– Sleeping sickness is caused by protozoan parasites (*Trypanosoma brucei* species).
– Transmitted exclusively by bites from infected tsetse flies living mainly in sub-Saharan African regions.
– Two forms exist: chronic West/Central African type (*T.b.gambiense*) & acute East African type (*T.b.rhodesiense*).
– Parasites multiply initially in blood/lymph before invading central nervous system.
– Symptoms progress from fever/joint pain/headache toward severe neurological impairment including disturbed sleep patterns.
– Rare transmission routes include congenital transfer or contaminated blood transfusion.
Understanding what causes sleeping sickness helps explain why controlling tsetse fly populations has been critical historically for reducing outbreaks across affected rural communities dependent on agriculture near riversides where these insects breed abundantly.
