Contents
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
- Convulsions
- Agitation
- Confusion
Then
- Apathy
- Depression
- Ataxia
- Dyskinesias
- Dementia
- Hypersomnolence
- Coma
If untreated, patients progress to coma, severe organ failure.
Death usually occurs within few months of onset of stage 2
Diagnosis
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