Human African Trypanosomiasis Quiz

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Questions and Answers

What is the main reservoir of infection for T.b. gambiense?

Humans (correct)

Birds

Wild animals

Cattle

How does T.b. rhodesiense typically infect humans?

Through sexual contact

Zoonotic transmission from wild animals (correct)

Via contaminated water

By inhalation of spores

What is the first clinical manifestation of a trypanosomal infection after a tsetse fly bite?

Trypanosomal chancre (correct)

Severe muscle pain

Sleep disturbances

Fever and headache

Which immune response is primarily generated against trypanosomal infection?

IgM antibody production (C) Signup and view all the answers

What symptom is characteristic of Stage 2 of the illness caused by T.b. gambiense?

Neurological symptoms (D) Signup and view all the answers

What is an early symptom of Stage 1 of T.b. gambiense infection?

Skin rash (B) Signup and view all the answers

What can cause the fluctuations in parasitaemia during trypanosomal infections?

Antigenic variation in parasite surface antigens (A) Signup and view all the answers

Which of the following is NOT a symptom of Stage 2 of the illness?

Increased appetite (C) Signup and view all the answers

What species of Trypanosoma causes Human African Trypanosomiasis?

Trypanosoma brucei gambiense (C) Signup and view all the answers

Which of the following is a major reservoir for T.brucei rhodesiense?

Wild animals (B) Signup and view all the answers

What insect is responsible for the transmission of Human African Trypanosomiasis?

Tsetse fly (C) Signup and view all the answers

Which stage of infection occurs 5-12 days after the tsetse fly bite?

Haemolymphatic Stage (C) Signup and view all the answers

What is the initial local effect at the site of the tsetse fly bite?

Trypanosomal chancre (B) Signup and view all the answers

What is the primary route of administration for Suramin?

Intravenously (B) Signup and view all the answers

Which of these changes occurs in the tsetse fly's salivary glands during the life cycle of Trypanosoma brucei?

Transformation into metacyclic trypanosomes (D) Signup and view all the answers

Which side effect is associated with Pentamidine?

Hypoglycaemia (D) Signup and view all the answers

What happens to the size of the trypanosomal chancre after it forms?

It typically increases for 2-3 weeks (A) Signup and view all the answers

Which geographical area is primarily affected by T.brucei gambiense?

West and Central Africa (C) Signup and view all the answers

Why are corticosteroids given during melarsoprol treatment?

To reduce the risk of encephalopathy (D) Signup and view all the answers

What is the dose regimen for Eflornithine?

400 mg/kg/day for 14 days (D) Signup and view all the answers

What major risk is associated with the use of Melarsoprol?

Reactive arsenical encephalopathy (A) Signup and view all the answers

Which statement about monitoring treatment success is correct?

CSF cell counts should fall below 5/mL. (D) Signup and view all the answers

What is a notable effect of delaying treatment in patients with CNS involvement?

Permanent neurological defect (B) Signup and view all the answers

What is a potential consequence of abnormal parameters post-treatment?

Indication of treatment failure (D) Signup and view all the answers

Which sign may occur in convulsions related to T.b.rhodesiense infection?

Kérandel’s sign (A) Signup and view all the answers

What is a common clinical feature of T.b.rhodesiense infection?

Intermittent fever (B) Signup and view all the answers

In advanced cases of T.b.rhodesiense, how are the tendon reflexes typically affected?

Exaggerated (B) Signup and view all the answers

Which diagnostic method is NOT useful in identifying T.b.rhodesiense?

Card agglutination test (CATT) (A) Signup and view all the answers

What type of complications can occur due to cardiac manifestations in T.b.rhodesiense infection?

Arrhythmias and congestive heart failure (A) Signup and view all the answers

What kind of findings are expected in CSF examination of late-stage T.b.rhodesiense?

Increased cell count and protein concentration (A) Signup and view all the answers

What characterizes the prognosis of untreated T.b.rhodesiense infection?

The condition is often fatal in weeks to months. (C) Signup and view all the answers

Which feature distinguishes T.b.rhodesiense from T.b.gambiense?

More acute symptom onset (A) Signup and view all the answers

Study Notes

Human African Trypanosomiasis (Sleeping Sickness)

Human African Trypanosomiasis (HAT), also known as sleeping sickness, is a parasitic disease caused by Trypanosoma brucei.
There are two main types of HAT:
- Trypanosoma brucei gambiense: Found in West and Central Africa. Humans are the primary reservoir.
- Trypanosoma brucei rhodesiense: Found in East and Southern Africa. Infected wild animals (reservoir).
Transmission occurs through the bite of tsetse flies (genus Glossina), found only in Africa.
Infected areas generally lie south of the Sahara and north of the Zambezi River.

Trypanosome Morphology

Trypanosomes are flattened, fusiform parasites with a kinetoplast and flagellum.
They have undulating membranes.
They exhibit active motility.
Two key forms exist— Trypanosoma brucei rhodesiense and Trypanosoma brucei gambiense.
They feature variable surface glycoprotein coats, enabling antigenic variation to evade the immune response.

Life Cycle

Tsetse flies ingest trypomastigotes (parasites) during a blood meal from an infected host.
Inside the fly's midgut, trypomastigotes multiply by simple fission.
They migrate to the salivary glands, undergoing morphological changes.
The kinetoplast moves anterior (in front of) the nucleus, and they transition to epimastigotes (crithidia).
Epimastigotes transform into metacyclic trypomastigotes in the salivary glands.
Metacyclic trypomastigotes are present in the fly's saliva up to 20 days after an initial blood meal.
The fly remains infectious throughout its life (several months).

Pathogenesis (Local Effects)

At the site of the tsetse fly bite, metacyclic trypanosomes cause an acute inflammatory lesion.
Lesion is known as a trypanosomal chancre.
This lesion then multiplies parasites, causing inflammation, edema, and local tissue destruction.
Parasites spread to local lymph nodes and then bloodstream.

Pathogenesis (Systemic Effects-"Stage 1")

Trypanosome multiplication in the lymphatic system leads to parasitaemia (presence of parasites in the blood) roughly 5-12 days post-bite.
Characterized by widespread lymphadenopathy and histiocytic infiltration, later progressing to fibrosis.

Pathogenesis (Systemic Effects– Meningo-encephalitic Stage-"Stage 2")

Parasites enter the central nervous system (CNS) through choroid plexus or transcytosis across endothelial cells.

Clinical Features: T. brucei gambiense

Stage 1: Chancre develops (1-2 weeks post-bite).
Early symptoms: fever, headache, joint pain, sometimes cutaneous oedema and lymphadenopathy.
Stage 1 Chancre (often resolves within weeks).

T. brucei gambiense (Stage 2)

Insidious onset of neurologic symptoms: headache, somnolence, listless gaze, extrapyramidal signs (tremors, spasticity).
Behavioral changes, psychiatric manifestations, CSF abnormalities.
Sleep patterns change with gradually longer sleep periods.
Speech and motor functions are severely affected; convulsions are rare.
Keárandel's sign (delayed hyperaesthesia).
Reflexes often over-exaggerated; plantar responses are extensor.
Death usually within months; CNS involvement may delay until up to a year post-infection.

Clinical Features: T. brucei rhodesiense

Illness more acute, onset of symptoms a few days after insect bite.
Common features: intermittent fever, rash.
Pleural and pericardial, and myocarditis (heart muscle inflammation) are common.
Lymphadenopathy is less prominent in the East African disease type compared to the West African type.
Hepatocellular jaundice and anemia are common.

Diagnosis

Direct parasite demonstration: Blood film (wet prep and Giemsa stain) is most likely positive in the haemolymphatic stage. It's even more positive in East African trypanosomiasis. Concentration techniques (e.g., buffy coat) improve sensitivity.
Aspirate from chancre or lymph node in acute infections (wet smear and Giemsa stain).
Bone marrow biopsy is also useful if other methods are negative.
CSF examination: increased cell count (> 5/mm³), increased CSF pressure, and increased IgM and total protein.

Treatment

Treatment depends on species, drug resistance pattern, and disease stage.

Treatment: T. b. gambiense

Stage 1: Pentamidine or Suramin.
Stage 2: Eflornithine or Melarsoprol and prednisolone (steroid used to reduce encephalopathy risk).

Treatment: T. b. rhodesiense

Suramin.
Melarsoprol in cases of relapse and second courses.

Prevention

Vector control (tsetse flies).
Early treatment of identified cases (humans are only reservoir in T.b. gambiense).
No vaccine.

Monitoring Treatment

Patient symptoms should resolve.
CSF cell counts fall below 5/mL and normal protein concentrations (potentially taking 6 months or more).

Relapse

In T. b. gambiense cases, relapse following treatment with different drugs can be treated with different drugs like Melarsoprol; Eflornithine can be used.
In T. b. rhodensiense, relapse is usually treated with a second course of Melarsoprol.

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Description

Test your knowledge on Human African Trypanosomiasis, specifically focusing on the infections caused by Trypanosoma brucei gambiense and rhodesiense. This quiz covers modes of transmission, clinical manifestations, and immune responses associated with the disease. Challenge yourself with questions on the symptoms and stages of infection.