Human African Trypanosomiasis

Introduction

Human African Trypanosomiasis (HAT), commonly known as sleeping sickness, is a parasitic disease caused by Trypanosoma species. It is transmitted by the bite of an infected tsetse fly (Glossina spp.). The disease is endemic to sub-Saharan Africa, primarily affecting rural populations with limited access to healthcare.

This eBook aims to provide UPSC aspirants with an in-depth understanding of HAT, covering its epidemiology, transmission, symptoms, diagnosis, treatment, and global efforts to control and eliminate it.

Understanding the Disease

Causative Agents

HAT is caused by two subspecies of Trypanosoma brucei:

• Trypanosoma brucei gambiense – Causes over 95% of cases and is prevalent in West and Central Africa.

• Trypanosoma brucei rhodesiense – Responsible for a smaller number of cases, mostly in East and Southern Africa.

 Transmission

The disease spreads through the bite of an infected tsetse fly. The parasites enter the human bloodstream, multiply, and invade the central nervous system, leading to severe neurological symptoms.

 Lifecycle of Trypanosomes

1. A tsetse fly bites an infected human or animal, ingesting trypanosomes.

2. The parasites develop in the fly’s midgut and migrate to its salivary glands.

3. When the fly bites another person, the trypanosomes enter the new host’s bloodstream and multiply.

4. They evade the immune system through antigenic variation, leading to chronic infection.

Clinical Features and Symptoms

Stages of the Disease

HAT progresses in two stages:

Stage 1 (Haemolymphatic Phase)

• Fever, headaches, joint pain, and itching.

• Enlargement of lymph nodes (Winterbottom’s sign in T.b. gambiense infections).

• Mild symptoms may persist for months or years in T.b. gambiense infections.

Stage 2 (Neurological Phase)

• Parasites invade the central nervous system (CNS).

• Sleep disturbances (reversal of sleep cycle), confusion, personality changes.

• Progressive mental deterioration, coma, and eventual death if untreated.

T.b. gambiense infections progress slowly, while T.b. rhodesiense infections advance rapidly, often leading to death within months.

Diagnosis and Detection

Early diagnosis is crucial for effective treatment. Common diagnostic methods include:

• Microscopy: Detection of parasites in blood, cerebrospinal fluid (CSF), or lymph node aspirates.
• Serological Tests: Card Agglutination Test for Trypanosomiasis (CATT) for T.b. gambiense.
• Molecular Techniques: Polymerase Chain Reaction (PCR) and Loop-mediated Isothermal Amplification (LAMP).

Staging is done by examining CSF for white blood cell count and presence of trypanosomes.

Treatment and Management

Treatment depends on the stage and type of infection:

Drugs for Early-stage HAT

• Pentamidine: Used for T.b. gambiense, effective in the first stage.

• Suramin: Used for T.b. rhodesiense, causes side effects like allergic reactions.

Drugs for Late-stage HAT

• Melarsoprol: Arsenic-based drug with severe side effects, including fatal encephalopathy.

• Eflornithine: Highly effective against T.b. gambiense, less toxic.

• NECT (Nifurtimox-Eflornithine Combination Therapy): A safer alternative for T.b. gambiense.

There is no vaccine for HAT due to antigenic variation of trypanosomes.

Epidemiology and Global Burden

• Geographic Distribution: Endemic in 36 African countries, particularly in regions with tsetse fly habitats.
• At-risk Population: Over 65 million people in rural Africa are at risk.
• Case Numbers: WHO reported fewer than 1,000 cases in 2020 due to control efforts.

Control and Prevention Measures

Efforts to control HAT focus on reducing transmission and providing early treatment.

 Vector Control

• Insecticide-treated traps to attract and kill tsetse flies.

• Sterile Insect Technique (SIT): Releasing sterile male flies to reduce fly populations.

Active Surveillance

• Mass screening in endemic areas using CATT and microscopy.

• Early treatment to prevent progression and transmission.

Community Awareness

• Educating communities on tsetse fly habitats and preventive measures.

• Encouraging the use of protective clothing and insect repellents.

Global Initiatives and WHO Roadmap

The World Health Organization (WHO) and partners aim to eliminate HAT through:

• The 2021-2030 NTD Roadmap: Targets elimination of T.b. gambiense HAT by 2030.
• Partnerships: Collaboration with NGOs, governments, and pharmaceutical companies.
• New Drugs and Diagnostics: Development of safer, more effective treatments.

The number of cases has significantly declined due to these efforts.

Conclusion

Human African Trypanosomiasis is a serious public health concern in Africa, but significant progress has been made toward its elimination. For UPSC aspirants, understanding HAT offers insights into global health governance, disease control strategies, and the impact of international cooperation on public health.

By studying such neglected diseases, future policymakers can contribute to strengthening global health systems and addressing similar challenges in India and beyond.

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