Sleeping Sickness: Causes, Symptoms, Diagnosis, Treatment and Prevention

Sleeping Sickness (African Trypanosomiasis) – Causes, Symptoms, Diagnosis, Treatment, and Prevention

~Introduction

Sleeping sickness, medically known as Human African Trypanosomiasis (HAT), is a parasitic disease caused by protozoa of the genus Trypanosoma. It is transmitted to humans through the bite of the tsetse fly (Glossina species), which is found only in sub-Saharan Africa. The name “sleeping sickness” comes from the characteristic disruption of the sleep-wake cycle that occurs in the late stage of the illness, when the parasite invades the central nervous system (CNS).

This disease has been known for centuries and has had devastating impacts on populations in Africa, both medically and socioeconomically. Despite major control programs, sleeping sickness still poses a threat to millions of people in rural regions where health systems are weak.

This article explores the causes, transmission, symptoms, stages, diagnosis, treatment, and prevention of sleeping sickness in detail.

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~What is Sleeping Sickness?

Sleeping sickness is a vector-borne parasitic disease that progresses slowly but can be fatal if untreated. It is caused by two subspecies of Trypanosoma brucei:

1. Trypanosoma brucei gambiense (T.b. gambiense):

   
   
   

   • Responsible for chronic infection.

   • Accounts for over 95% of reported cases.

   • Found in West and Central Africa.

   • Progresses over months to years.

2. Trypanosoma brucei rhodesiense (T.b. rhodesiense):

   • Causes an acute infection.

   • Found in East and Southern Africa.

   • Progresses rapidly, often within weeks to months.

   • Accounts for a small proportion of cases but is more severe.

Both forms of the disease can be fatal without treatment, but they differ in their clinical presentation and epidemiology.

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~Transmission

The parasite is transmitted primarily by the tsetse fly, which becomes infected when it feeds on the blood of an infected human or animal. The cycle of transmission occurs as follows:

1. A tsetse fly bites an infected host (human or animal) and ingests the parasite.

2. The parasite develops inside the fly for about 2–3 weeks.

3. When the infected tsetse fly bites another person, it injects the parasite into the bloodstream.

4. The parasites multiply and spread throughout the body, eventually crossing the blood-brain barrier into the central nervous system in later stages.

It is important to note:

• Animals, particularly cattle and wild game, act as reservoir hosts, especially for T.b. rhodesiense.

• Rare cases of mother-to-child transmission, sexual transmission, and accidental infections in laboratories have been reported.

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~Stages of the Disease

Sleeping sickness progresses in two distinct stages:

1. Hemolymphatic Stage (Early Stage)

• Parasites are found in the blood, lymph, and tissue fluids.

• Symptoms include:

  • Intermittent fever

  • Headaches

  • Joint and muscle pain

  • Swollen lymph nodes (especially at the back of the neck – called Winterbottom’s sign)

  • Skin rashes

  • Fatigue and weakness

  • Enlarged spleen and liver

At this stage, the disease is easier to treat because the parasite has not yet invaded the CNS.

2. Neurological Stage (Late Stage)

• Parasites cross the blood-brain barrier and invade the central nervous system.

• Symptoms include:

  • Confusion and personality changes

  • Disturbances in coordination

  • Anxiety and irritability

  • Disruption of the sleep cycle (patients feel sleepy during the day and awake at night)

  • Tremors and seizures

  • Progressive neurological decline leading to coma

This stage is more difficult to treat and often fatal if untreated.

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~Clinical Features

The clinical features vary depending on the subspecies:

• T.b. gambiense (chronic form):

  • Symptoms may take months or years to develop.

  • Patients may initially show mild symptoms, which can be mistaken for malaria or other febrile illnesses.

  • Neurological symptoms develop slowly.

• T.b. rhodesiense (acute form):

  • Rapid onset of symptoms within weeks.

  • More severe fever, weight loss, and heart involvement.

  • Neurological symptoms appear earlier compared to the gambiense form.

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~Diagnosis

Accurate diagnosis is crucial for effective treatment, as drugs differ depending on the disease stage. Diagnosis involves:

1. Clinical Examination

   • History of exposure in endemic areas.

   • Symptoms such as swollen lymph nodes (Winterbottom’s sign).

2. Parasitological Tests

   • Microscopic detection of parasites in blood, lymph node aspirates, or cerebrospinal fluid (CSF).

   • Thick and thin blood smears.

3. Serological Tests

   • Card Agglutination Test for Trypanosomiasis (CATT) – useful for mass screening of T.b. gambiense.

4. Lumbar Puncture (Spinal Tap)

   • To check for parasites in CSF and assess white blood cell count.

   • Helps determine whether the disease has progressed to the neurological stage.

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~Treatment

Treatment depends on the stage and subspecies of the parasite. Drugs used include:

For Early Stage (before CNS involvement):

• Pentamidine – effective for T.b. gambiense.

• Suramin – used for T.b. rhodesiense.

For Late Stage (after CNS involvement):

• Melarsoprol – effective against both forms but has serious side effects (arsenic-based drug).

• Eflornithine – effective against T.b. gambiense, safer but requires complex administration.

• NECT (Nifurtimox-Eflornithine Combination Therapy):

  • A more recent, effective, and safer treatment for T.b. gambiense.

New Developments

• Fexinidazole, an oral drug approved in 2019, is a promising alternative for T.b. gambiense treatment, making therapy easier and more accessible.

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~Complications

If untreated, sleeping sickness leads to severe complications:

• Progressive neurological damage

• Endocrine dysfunctions

• Organ damage (heart, liver, spleen)

• Irreversible mental decline

• Death

Even after treatment, some patients may experience relapses or permanent neurological damage.

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~Prevention and Control

Since there is no vaccine available, prevention focuses on controlling the tsetse fly and minimizing exposure. Strategies include:

1. Vector Control

   • Insecticide-treated targets and traps.

   • Clearing vegetation where tsetse flies breed.

   • Spraying insecticides in affected areas.

2. Personal Protection

   • Wearing protective clothing (long sleeves, neutral colors).

   • Using insect repellents.

3. Screening and Case Detection

   • Mass screening programs to identify and treat cases early.

   • Reduces transmission within communities.

4. Animal Reservoir Control

   • Treating livestock that act as reservoirs.

   • Vector control in grazing areas.

5. Health Education

   • Raising awareness about transmission, symptoms, and treatment availability.

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~Global Burden and Epidemiology

• Sleeping sickness is confined to 36 sub-Saharan African countries where tsetse flies are found.

• At the beginning of the 21st century, there were nearly 300,000 new cases annually.

• Thanks to large-scale control efforts, reported cases dropped to under 1,000 by 2019, marking significant progress.

• Most cases today are due to T.b. gambiense in Central and West Africa.

• T.b. rhodesiense cases remain sporadic but more severe.

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~Socioeconomic Impact

Sleeping sickness has wide-reaching consequences:

• Health Impact: High mortality and chronic disability.

• Economic Impact: Reduces workforce productivity, especially in agriculture.

• Healthcare Burden: Limited resources in rural Africa make diagnosis and treatment challenging.

• Education Impact: Children in endemic regions miss school due to illness.

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~Research and Future Directions

Recent advances give hope for eventual elimination of sleeping sickness:

• Oral therapies like fexinidazole simplify treatment.

• Improved diagnostics allow faster detection.

• WHO targets aim to eliminate sleeping sickness as a public health problem by 2030.

• Research is ongoing into vaccines, though challenges remain due to parasite antigenic variation.

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~Conclusion

Sleeping sickness remains one of the most significant neglected tropical diseases, affecting some of the poorest regions of Africa. Caused by Trypanosoma parasites and transmitted by the tsetse fly, it has devastating effects on individuals, families, and communities.

The disease progresses in two stages: the early hemolymphatic stage and the late neurological stage, with the latter leading to disruption of sleep cycles and eventually death if untreated. Diagnosis requires careful laboratory testing, and treatment options differ depending on the disease stage and parasite subspecies.

Encouraging progress has been made through mass screening, vector control, and new drugs like fexinidazole, but continued efforts are essential to achieve elimination goals. Global cooperation, research, and investment in healthcare infrastructure remain key to finally eradicating this deadly disease.