Trypanosoma cruzi - Chagas Disease

Diagnosis

Indications for Testing

• Residency in endemic area
• Recent travel to endemic area
• Cardiomyopathy or prototypical gastrointestinal disease without obvious etiology

Laboratory Testing

• Trypanosomiasis diagnosis (CDC, 2014)
• Acute phase (first 60-90 days)
  • Direct detection of parasites on blood smear (Giemsa stain)
  • IgM may be useful in acute infection
  • Polymerase chain reaction (PCR) is very sensitive when available
• Nonacute (chronic) phase (>90 days)
  • IgG confirms chronic disease – by indirect fluorescent antibody (IFA), enzyme-linked immunosorbent assay (ELISA), or indirect hemagglutination antibody (IHA)
    • World Health Organization (WHO) recommends at least two tests to confirm disease
  • Cross-reactivity with Leishmania spp may occur
  • PCR requires further validation

Differential Diagnosis

• Muscular disease
  • Trichinella spiralis infection
  • Inflammatory myopathies
• Cardiomyopathy
  • High-output failure
    • Anemia
    • Beriberi
    • Paget disease
    • Hyperthyroidism
  • Acute rheumatic fever
  • Valvular disease
  • Congenital heart disease
  • Acute myocarditis
• Megaesophagus
  • Achalasia
  • Strictures
  • Esophageal cancer
• Megacolon
  • Hirschsprung disease
  • Diabetic gastroenteropathy
  • Colonic stricture
  • Systemic sclerosis
  • Amyloidosis
• Neurologic disease
  • Myotomic dystrophy
  • Parkinson disease
  • Chronic opiate ingestion
  • Severe hyperthyroidism

Background

Epidemiology

• Prevalence
  • U.S. – almost exclusively found in immigrants from Central and South America
  • Worldwide – 16-18 million individuals infected
• Transmission
  • Triatominae vector species (kissing bug)
  • Maternal transplacental transfer (congenital)
  • Blood transfusion from infected donor
  • Organ transplantation
  • Ingestion of contaminated food/water (rare)

Organism

• The genus Trypanosoma contains many species of protozoans
  • Only three cause human disease – T. cruzi, T. brucei gambiense, and T. brucei rhodesiense
  • Vectorborne from the reduviid Triatoma gerstaeckeri and others
    • Exposure to feces deposited on skin by infected bugs

Clinical Presentation

• Acute phase
  • Mild symptoms occur for 2 weeks to 3 months
    • Romaña sign – unilateral painless edema of palpebral and periocular tissues
  • Initial signs include malaise, fever, anorexia, rash, and edema
  • Acute myocarditis in small percentage of cases
  • Indurated area of erythema and swelling (chagoma) may indicate parasite entry site
  • Frequently undetected at this stage
• Chronic phase
  • May manifest decades later
  • Cardiomyopathy with arrhythmia
    • ~20-30% of patients (Bern, 2015)
    • Earliest sign is conduction defects – patient usually asymptomatic
    • Symptoms of biventricular failure – peripheral edema, hepatomegaly
    • ~60% experience sudden cardiac death
  • Digestive system complications
    • Megacolon
    • Ranges from mild achalasia to megaesophagus
• Congenital disease
  • Highest risk for infection when maternal parasitemia is high during acute phase
  • Prematurity, hepatosplenomegaly, meningitis/encephalitis
• Immunocompromised hosts
  • Organ transplant recipients – more severe clinical spectrum that can include acute myocarditis and congestive heart failure
  • Immunocompromised patient with reactivation – most common presentations are meningoencephalitis, brain abscess, and acute myocarditis