African Sleeping Sickness
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Organism

African Sleeping Sickness is one of two diseases cause by Trypanosome parasites

Transmission

Tsetse fly (bite during the day)

Epidemiology

African Sleeping Sickness is caused by

  • Trypanosoma brucei gambiense (West coast of Africa)
  • Trypanosome brucei rhodesiense (East coast of Africa)

 

Clinical features and pathogenesis

  • T.gambiense- causes slow wasting illness with long latency
  • T.rhodesiense- causes more rapidly progressive illness
  • Trypanosomes injected in saliva of tsetse fly when bites
  • Localised inflammatory reaction
  • Tender subcutaneous (chancre) develops at site  (2-3 days after bite)

 

Stage 1 (haemolymphatic)

  • Multiplication of trypanosomes in the lymphatics and bloodstream leads to parasitaemia 5-12 days after bite
  • Trypanosomes evade the immune response by antigenic variation (meaning they switch to be no longer recognized by existing antibodies the body has made)
  • Results in peaks of parasitaemia and production of auto-antibodies
  • The disease progresses into immunosuppression with hypergammaglobulinaemia
  • Infiltration of endocrine organs occurs
  • Alteration of hormonal balance and circadian rhythm.

Features of Stage 1

  • Headache
  • Rash
  • Fever
  • Hepatosplenomegaly  and Lymphadenopathy secondary to immune activation
  • Joint pains
  • Post cervical lymphadenopathy (Winterbottom’s sign)

Stage 2 (meningoencephalytic)

Weeks after initial infection, parasites enter the CNS via the choroid plexus and infiltrate the white matter drawing in inflammatory cells and stimulating macrophages.

Initially

Then

If untreated, patients progress to coma, severe organ failure.
Death usually occurs within few months of onset of stage 2

Diagnosis

Trypanosoma on blood film
Trypanosoma on blood film

Trypomastigotes isolated in blood film (thick and thin)/bone marrow/ lymph node aspirate/CSF.
Serology may be helpful.

Treatment

More effective if started before neurological involvement.
Pre-CNS involvement: (don’t penetrate BBB) suramin / pentamidine
Post-CNS involvement: melarsoprol/nitrofurazone

Prevention

Prevention of insect bites
Insect repellant, long sleeves and bed nets

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Dr Tom Leach

Dr Tom Leach MBChB DCH EMCert(ACEM) currently works as a GP Registrar and an Emergency Department CMO in Australia. He is also a Clinical Associate Lecturer at the Australian National University. After graduating from his medical degree at the University of Manchester in 2011, Tom completed his Foundation Training at Bolton Royal Hospital, before moving to Australia in 2013. He started almostadoctor whilst a third year medical student in 2009. Read full bio

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