Chagas' disease

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Chagas' disease (American trypanosomiasis) is caused by Trypanosoma cruzi a protozoan transmitted by blood sucking insects of the genus Triatoma such as the kissing bug Triatoma infestans. Contamination of acai fruit with the protozoa has also resulted in rare infective outbreaks[1]. More importantly the disease can be transmitted by blood transfusions, organ transplantation and mother-to-child transmission which is of public health concern with immigrants. It is most prevalent in Bolivia where 20% or more of the adult population are likely to be assymptomatic carriers.

Contents

Presentation

  • Insidious usually
    • Symptoms can appear 1—2 weeks after triatomine bug bites, usually a few months after infected blood transfusion
    • Over 90% then settle, most having positive serum antibodies against Trypanosoma cruzi, normal ECG, and normal findings in chest, oesophagus, and colon
    • 30 to 40% develop after 15 to 30 years the determinate chronic disease
      • Reactivation of Chagas' disease can occur in the immunologically compromised
      • Chagas' cardiomyopathy
        • Right bundle branch block or left anterior hemiblock usually first
        • Biventricular failure
        • LV apical aneurysm
        • Arrhythmias
      • Dysphagia (Chagas' megaoesophagus)
      • Constipation ((Chagas' megacolon)
  • Occasionally acute with severe life threatening illness (perhaps 5-10%)

Diagnosis

  • Acute
    • Blood film for trypomastigotes
  • Congenital
    • Microhaematocrit
  • Chronic
    • Serology and clinical

Treatment

  • Prevention (ie vector control by insecticides and environment)
  • Antitrypanosomal therapy for chronic Chagas disease remains controversial. However mother-to-child transmission can be avoided by treating infected women before pregnancy
  • So mainly symptomatic but:
  • Benznidazole for 60 days eliminates infection in 60% infected children [2]
  • Nifurtimox also has an evolving place in therapy.

References