African sleeping sickness is a parasitic disease that affects humans and domestic animals. It was first discovered in 18th century in humans and cattle which caused a fatal sleeping disturbance. It is a parasitic disease caused by genus Trypanosoma found in tsetse fly. This infection is transmitted to humans and animals by the bite of tsetse fly of the genus Glossina. African sleeping sickness is seen in sub-Saharan Africa. It affects the population with poor living conditions and people with limited access to health services.(1,2)
What is African Sleeping Sickness?
African sleeping sickness is also known as Human African trypanosomiasis (HAT). It is a disease caused by the bite of tsetse fly transmitting the parasite trypanosoma causing acute and severe illness.(2,3) Tympanosomes is found in the blood and cerebrospinal fluid of the affected people. There are two different types of African sleeping sickness:
- Trypanosoma brucei gambiense is responsible for 97% of cases
- Trypanosoma brucei rhodesiense is responsible for 3% of cases.(2)
Symptoms of African Sleeping Sickness
There are two stages of the disease and the symptoms vary based on the stage:
- Early or Hemolymphatic Stage: In early stage, the symptoms of African sleeping sickness occur within one to three weeks after the bite of tsetse fly involving the lymphatic system and circulatory system of the body. The affected person may experience fever, headache, painful joints, tiredness and weight loss. As the African sleeping sickness disease progresses the patient may develop multiple organ infection such as – the patient may also develop nodules at the back of the neck ( lymphadenopathy) , enlargement of spleen and liver, eye infection, fertility issues, cardiac issues such as congestive heart failure, pericarditis (inflammation of the layer surrounding the heart).
- Late or Encephalitic Stage: The symptoms occur insidiously in which it involves the brain and spinal cord. The trypanosomes cross the blood-brain barrier and affect the central nervous system. In chronic phase, the patient presents with:
- Motor system disturbances such as tremors, increased muscle tone, difficulty in walking, abnormal movements.
- Sensory system disturbances such as double vision, increased sensitivity, papilloedema.
- Mental disturbances such as behavioural disturbances, anxiety, irritability, hallucinations.
- Sleep disturbances such as daytime sleepiness, reversal of the sleep cycle, uncontrollable sleep episodes.(1)
Causes of African Sleeping Sickness
African sleeping sickness is caused by the parasite called as Trypanosoma. The parasite is transmitted to humans by the bite of tsetse fly. The trypanosome spreads in the blood, lymph nodes and organs such as heart, spleen, eye at the early stage of the disease. As the African sleeping sickness disease progresses the parasite crosses the blood-brain barrier and enters in to the brain and spinal cord causing infection and inflammation of the brain (Meningoencephalitis).
Epidemiology of African Sleeping Sickness
African sleeping sickness exists in two forms with different clinical presentation and epidemiology. While Trypanosoma brucei gambiense is responsible for the West African sleeping sickness; Trypanosoma brucei rhodesiense is responsible to cause the East African sleeping sickness. Humans are the main carrier of Trypanosoma brucei gambiense and animals remain the main reservoir for the parasite Trypanosoma brucei rhodesiense. This disease is more prevalent in the rural areas where the humans tsetse fly are in contact. People are infected during the engaging activities that expose them to tsetse fly such as farming, fishing etc. All age groups, both male and female have higher prevalence of acquiring the disease. Trypanosoma brucei rhodesiense is seen in tourists who have visited national parks, game reserves in Tanzania, Kenya, Zimbabwe, Uganda.(3)
Diagnosis of African Sleeping Sickness
The clinical presentation of the African sleeping sickness is similar to malaria, typhoid, tuberculosis, viral encephalitis, HIV infection, leishmaniasis. It requires a detailed investigation before the final diagnosis. The tests that are conducted to diagnose African sleeping sickness are:
Blood test, lymph node aspiration, bone marrow aspiration tests are used to detect the presence of the parasite Trypanosoma brucei rhodesiense.
Antibody – detecting card agglutination trypanosomiasis test (CATT) is used to detect the parasite Trypanosoma brucei gambiense.
Cerebrospinal fluid (CSF) investigation helps to detect the chronicity of the African sleeping sickness. White blood cells more than 5µl or increased protein content >370mg/litre indicates the chronic stage of the African sleeping sickness disease. Cerebrospinal fluid Polymerase chain reaction (PCR) test has 96% sensitivity rate and it is used to detect the trypanosome DNA. High immunoglobulin M level indicates the infection in CSF. Electroencephalogram (EEG) is a test to check the electrical activity of the brain. Abnormality in the EEG test indicates the chronic stage or encephalitic stage of the African sleeping sickness.
CT scan & MRI is a test which shows image of the various structures of the brain. In African sleeping sickness, CT scan and MRI scan are used to monitor the response to the treatment and to detect the areas of the raised intracranial pressure.(1,4)
Treatment for African Sleeping Sickness
The primary step is to prevent the disease of African sleeping sickness. An awareness and avoidance of the tsetse fly bite is the important step to prevent the African sleeping sickness. There is no vaccine or chemoprophylaxis to prevent the disease. Travellers visiting the savannah areas, central and east Africa are at risk and necessary precautions have to be carried out to prevent the disease.(4)
Secondary care is to get the treatment after acquiring the African sleeping sickness disease. Early detection of the African sleeping sickness disease helps in the better recovery and tolerance to the treatment. The treatment for African sleeping sickness disease depends upon the type of the parasite and the disease stage.
Drug therapy for both the disease types include:
Trypanosoma Brucei Gambiense
At the first stage of the gambiense, pentamidine is given intramuscularly at 4mg/kg per day for 7 days. At the later stage of the gambiense, nifurtimox and eflornithine combination therapy is administered. Nifurtimox is given at 15mg/kg per day orally three times a day and Eflornithine is given at 400mg/kg intravenously in two 2-hours infusions for 7 days.
Trypanosoma Brucei Rhodesiense
At the first stage of the rhodesiense, Suramin is given 20mg/kg per day intravenously once a week for 5 weeks. At the later stage of the rhodesiense, melarsoprol is given 2.2mg/kg per day intravenously for 10 days.(1)
Prognosis of African Sleeping Sickness
Early detection and management of the African sleeping sickness is important to reduce the mortality and morbidity rate. The differential diagnosis with malaria, typhoid, and viral encephalitis plays an important role in identifying the clinical features and the parasite in the serological investigations. Some patients have shown drug resistance to Pentamidine and Melarsoprol. Clinicians are suggesting a combination of the pentamidine and melarsoprol for drug resistance patients.(3) If the African sleeping sickness patient is not treated they may progress to final stage of the disease which is characterised by epilepsy, severe somnolence, multiple organ failure, coma and eventually death.(1)
Recovery of African Sleeping Sickness
Understanding the nature of the African sleeping sickness disease and using reliable diagnostic procedures are important for early detection of the parasitic disease. African sleeping sickness is fatal if it is left untreated or inadequately treated. Higher mortality is seen in patients in second stage of the disease.
African sleeping sickness is a parasitic disease occurring in the rural areas of east and west Africa. It affects the population with poor living conditions and people with limited access to health services. The symptoms vary from fever, malaise, joint pain, multiple system infection at the early stage to central nervous system infection in the late stage. Treatment with drugs such as pentamidine, suramin, melarsoprol, eflornithine, nifurtimox have shown to aid the recovery. If the African sleeping sickness condition is left untreated or inadequately treated, it may cause serious neurological damage which will lead to death of the patient. Early detection and treatment can help the patient to recover.
- Peter G.E. Kennedy. (2004, Feb) Human African trypanosomiasis of the CNS: current issues and challenges, The Journal of Clinical Investigation. 113(4): 496 – 504.
- Peter G E Kennedy. (2013) Clinical features, diagnosis, and treatment of human African trypanosomiasis (sleeping sickness). Lancet Neurology. 12: 186–94.
- August Stich. (2002) Human African trypanosomiasis. BMJ. 325: 203–6.
- Hedley, L. et. al. (2016, Oct) African sleeping sickness. British Journal of Hospital Medicine. Vol 77, No 10.