Sleeping sickness

From Ganfyd

Jump to: navigation, search

Limited to the distribution in sub-Saharan of the Tsetse fly which is the intermediate host of the protozoa Trypanosoma brucei. Disease control lapsed in the 1990s but is now back to the order of less than 3000 cases a year [1]compared to the millions that died at the beginning of the 20th century. However West Africian sleeping sickness can have incubation periods of over 30 years and so could present anywhere in the world in any one who has visited an endemic area.

  • West African sleeping sickness (Gambiense trypanosomiasis) due to Trypanosoma brucei gambiense
    • Typical cause untreated 3 years
  • East African sleeping sickness (Rhodesiense trypanosomiasis) due to Trypanosoma brucei rhodesiense
    • Typical course untreated months
    • Tyyranosomal chancre in about 20%
  • Nagana in animals caused by Trypanosoma brucei brucei

Contents

Infection

  • Some mammals can harbour asymptomatic infection of the human Trypanosoma subspecies (so can some humans !)
  • Is related to contact time with the Tsetse fly. Thus tourists are far less likely to get the disease (but if they do get it tend to an acute presentation with high fever, chancre, rash)
  • Long incubation so many first manifest many years after exposure
  • Normal protection in man offered by trypansosome lytic factor, which has subunit components of apolipoprotein L1 and haptoglobin-related protein[2].

Clinical

  1. Haemolymphatic stage
    • Chronic intermittent fever
    • Headache
    • Puritis
    • Lymphadenopathy
    • Sometimes hepatosplenomegaly
    • Occasional myopericarditis (esp rhodesiense)
    • Occasional endocrine dysfuction (esp rhodesiense)
  2. Meningoencephalitic
    • Sleep disturbance
    • Other neuropsychiatric manifestations
      • Tremor
      • Palsies
      • Dyskinesias
      • Psychosis
    • Fever rare

Diagnosis

LogoKeyPointsBox.pngCSF examination is essential to differentiate between first and second stage
  • Contact either the Institute of Tropical Medicine, Antwerp, Belgium or Institut de Recherche pour le Developpement, Bobo Dioulasso, Burrkina Faso for access to the tests below.[1]
  • Card agglutination test (CATT) the usual practice in endemic regions[3]
  • Immunofluorescense
  • Blood/lymph node aspirate fresh films
  • PCR being developed[4]

Prevention

  • Surveillance and vector control
    • Almost eradicated disease in colonial era

Treatment

(Note:as of 2017 the drugs below can be obtained free of charge with distribution coordinated via WHO Geneva)

  1. Haemolymphatic stage
    • Pentamidine in West African sleeping sickness parentally once a week
    • Suramin in East African sleeping sickness (Take advice on regime as these vary)
  2. Meningoencephalitic (second stage disease)
    • Melarsoprol is now second line due to risk of fatal encephalopathic syndrome which has occurred in up to 9% in East Africian second stage disease.
    • Eflornithine is now first choice in West African sleeping sickness usually in combination with nifurtimox (NECT regime- note nifurtimox is only licensed to treat American trypanosomiasis).[1]

Possible treatments

Parfuramidine has proved too nephrotoxic to use. Fexinidazole is in phase 3 studies and is likely to be available as an oral ten day course if licensed. A benzoxaborole SCYX-7158 that promises to be curative at single dose has entered phase 2 studies as of 2017.[1]

External link

References