Sleeping sickness is caused by a parasitic protozoon called Trypanosome. These single-celled organisms are found primarily in Sub-Saharan Africa and are spread through the bite of flies. The disease is called sleeping sickness due to the constant sleepy feeling that's the result of damage to the central nervous system. Sleeping sickness is very serious because it can be fatal if left untreated. Visitors to Africa should take great precaution, because symptoms are not immediately evident and may take weeks or months to show up.
Organism and Vector
According to the World Health Organization, there are two types of Trypanosome parasites. Trypanosoma brucei gambiense is responsible for more than 90 percent of sleeping sickness and chronic illness. Symptoms may take months or years before the infected person becomes aware of the disease, and by this time the disease has advanced to the central nervous system. The second organism is Trypanosoma brucei rhodesience, which represents fewer than 10 percent of infected cases with an acute infection. In this case, symptoms are observed within a few weeks or months and the disease spreads rapidly to the central nervous system.
The vector responsible for spreading the disease is the Tsetse fly. These flies feed by biting infected animals or humans to obtain a blood meal and in turn spread the trypanosome parasite to others.
Symptoms
There are two stages of the disease that present different symptoms. The haemolymphatic phase includes fever, malaise, weight loss, itching, headaches and joint pain. The central nervous system phase presents neurological problems such as severe headaches, behavior change, mood disorders, drowsiness and an uncontrollable urge to sleep.
Diagnosis
The primary method of diagnosis is to identify the organisms under the microscope. Specimens diagnosed are blood, cerebrospinal fluid, lymph fluid from the nodes and chancre fluid from the bite site of the tsetse fly. Another diagnostic method is called the ELISA test, which uses antibodies to detect the presence of the parasite.
Treatment
Treatments also vary by stage. First-stage treatments are more effective, less toxic to the individual, and have a higher rate of cure. Pentamidine is used in the treatment of T. gambiense and has few side effects. Suramin is used primarily for T. rhodesiense but produces many side effects, such as urinary tract and allergic reactions.
Second-stage treatments are more toxic and harder to administer because of the difficulty of reaching the brain to kill the parasite. Melarsoprol is used to treat both types of parasites but has a serious side effect, which is brain toxicity. Eflornithine is used to treat T. gambiense and is less toxic than Melarsoprol.
Prevention
Prevention is primarily aimed at vector control of the tsetse fly. It's recommended that areas where the fly is found should be avoided. Insect repellents such as DEET and Permethrin help reduce fly bites. It's also recommended that travelers wear medium weight clothes in neutral colors; bright colors tend to attract flies.
References
- World Health Organization: African trypanosomiasis (sleeping sickness)
- U.S. National Library of Medicine and the National Institutes of Health: Sleeping sickness
- Centers for Disease Control and Prevention: TRYPANOSOMIASIS, HUMAN AFRICAN (HAT, AFRICAN SLEEPING SICKNESS)
- Stanford University: African Trypanosomiasis African Sleeping Sickness
