Sleeping sickness: Description
Sleeping sickness (trypanosomiasis) is caused by the unicellular parasite Trypanosoma brucei. There are two forms of the disease – the West African and the East African variants:
- The East African form accounts for only about two percent of all cases of sleeping sickness. It progresses very rapidly. This means that there is very little time for diagnosis and treatment. However, this form of sleeping sickness mainly affects animals and rarely humans.
- The West African form of sleeping sickness is more common, progresses more slowly, and is sometimes not diagnosed until years after infection.
The geographic boundaries of the two forms of the disease are increasingly blurred. For example, in Uganda, an East African country, both forms already occur in different areas. Although data are hard to come by, the Democratic Republic of Congo and the Central African Republic are particularly affected by the tropical disease. However, since the data come from different health systems, it can be assumed that sleeping sickness is also present in other countries in this region.
Trypanosomes belong to the protozoan family, as does, for example, the causative agent of malaria. Similar to malaria, sleeping sickness cannot be transmitted from person to person. Rather, the pathogens of the disease are transmitted to humans by the bloodsucking tsetse fly when it bites.
The West and Central African variant of sleeping sickness is caused by the subspecies Trypanosoma brucei gambiense, while the East African variant is caused by Trypanosoma brucei rhodesiense.
Sleeping sickness: symptoms
After being bitten by a tsetse fly and transmitting the trypanosomes, a painful, inflamed redness may develop at the site of the bite within one to three weeks (subspecies rhodensiense) or weeks to months (subspecies gambiense). Physicians refer to this as a so-called trypanosome chancre. The injection site is often in the face or neck area.
Finally, the trypanosomes attack the central nervous system (meningoencephalitic stage). As a result, the eponymous disturbances of the sleep-wake rhythm occur. In addition, paralysis, convulsions or Parkinson-like symptoms (rigor = muscle rigidity, tremor = trembling, ataxia = disturbed coordination of movement) may occur. Behavioral disturbances and irritability also set in. Finally, the patient falls into a coma and dies.
This general course of the disease is seen in both forms of sleeping sickness. However, there are some differences in detail:
West African sleeping sickness
East African sleeping sickness
East African sleeping sickness (causative agent: Trypanosoma brucei rhodesiense) is basically a rapid and more serious variant of the more common West African form. Fever and chills, as well as a painful, inflamed puncture site, may become apparent days to weeks after being bitten by the tsetse fly. The parasites quickly infect the lymphatic and blood systems and spread throughout the body. Swelling of the lymph nodes, liver and spleen can be palpable after only a few weeks. Irritability, sleep disturbances and paralysis can occur after weeks to months. After a few months, the patient falls into a coma and dies of multiple organ failure.
Sleeping sickness: causes and risk factors
Sleeping sickness is caused by the parasite (protozoan) Trypanosoma brucei, and there are two subspecies: T. b. rhodesiense and T. b. gambiense. They are transmitted by the bites of the blood-sucking tsetse fly from either infected animals (subspecies rhodesiense) or infected humans (subspecies gambiense) to healthy people.
Since trypanosomes regularly change their surface, they are not recognized quickly enough by the immune system. This so-called antigenic change explains why the human immune system is so helpless in the face of sleeping sickness.
Sleeping sickness: examinations and diagnosis
Patients in Germany are suspected of having sleeping sickness when they come to the doctor with symptoms such as fever, headache, pain in the limbs, and swelling of the lymph nodes, and tell of a recent long stay in Africa (short vacationers are not the typical patients).
The diagnosis can be confirmed by detecting trypanosomes in the patient’s body. For this purpose, the physician can take sample material from the injection site, a blood sample or a sample of cerebrospinal fluid (CSF) and send it to the laboratory for analysis.
A specialized physician (tropical medicine specialist) should diagnose and treat sleeping sickness.
Sleeping sickness: treatment
Sleeping sickness: therapy before infestation of the brain
If the trypanosomes have not yet attacked the central nervous system, the drugs pentamidine and suramin are used. They combat the protozoa, but have some side effects due to their toxicity. Both drugs were developed before and during the Second World War, respectively.
Sleeping sickness: Therapy for infestation of the nervous system
If the brain is already affected by sleeping sickness, further drugs are necessary. This is because pentamidine and suramin cannot cross the blood-brain barrier and therefore do not act in the brain. Some of these drugs are chemotherapeutic agents that are also used in cancer and HIV therapy. Unfortunately, these drugs can cause severe side effects:
- Melarsoprol: arsenic compound. Kills trypanosomes, but has dangerous side effects such as damage to the brain, which is fatal in about three to ten percent of cases. The drug is currently not approved in the EU and Switzerland.
Sleeping sickness: course of the disease and prognosis
If left untreated, sleeping sickness is usually fatal. However, if the disease is detected early and treated consistently, doctors can often cure patients. However, this is a process that often takes months to years. Regular blood draws, as well as spinal cord punctures, are part of the monitoring to ensure treatment success.
For a long time, many of the drugs for sleeping sickness were not available. Since 2001, there has been a cooperation between the World Health Organization (WHO) and some private pharmaceutical companies so that the most important drugs against sleeping sickness can be supplied free of charge to affected countries. Médecins Sans Frontières (MSF) is responsible for the logistics of this cooperation. In this way, the number of cases of sleeping sickness has been significantly reduced.
Sleeping sickness: prevention
Since there is no vaccination against sleeping sickness, one should effectively protect oneself from insect bites when traveling to risk areas. This includes wearing long pants and long sleeves and using insect repellents.
