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TM: American Trypanosomiasis (Chagas disease) (ii) Phases (Acute phase…
TM: American Trypanosomiasis (Chagas disease) (ii) Phases
Acute phase
after 1-2 wks (incubation period)
+ve smear, culture, PCR
Romanas sign
unilateral painless periorbital swelling
swollen eyelids, narrows eye
chagoma of eye
microscopically detectable parasitaemia lasting 8-12 wks
local multiplication
symptoms usually mild + non-specific
may be asymptomatic, hence infrequently recognised
rarely a chagoma (skin nodule) may develop @ inoculation site 2-4 days later - erythematous, painful, brawny, firm
neuropathy may be present @ site - resolves
lasts 2 wks then area is depigmented
dissemination
fever
lymphadenopathy
hepatosplenomegaly
myocarditis (CHF, tachycardia, cardiomegaly, arrhythmias, rarely mortality)
meningoencephalitis (rarely mortality)
orchitis
thyroiditis
5-10% fatality rate
resolves after 4-12 wks then patients enter latent phase
Chronic phase
after 4-8 wks
-ve smear
+ve PCR in 20-70%
serological dx (assays)
indeterminate form
no signs/symptoms
70-80% of infected people have this throughout life
Determinate form
20-30% of those infected have clinically evident disease progression over yrs-decades
following latent period from acute disease (10-30 yrs)
Chagas CM or GI Chagas disease or both
reasons
parasite persistence
inflamm host immune response (most important determinant of progression)
parasite factors (e.g. strain)
ongoing superinfection
Chagas heart disease
inflamm infiltrate
dilated CM
thin myocardium
impaired contractility
balloons out - can be > 50% of total chest diameter
apical aneurysm
rupture can be fatal
pericardial effusions when pericardium damaged
necrotic degenerative process
reactive + reparative fibrosis
affects conduction system + myocardium (electrical instability + ventricular dysfunction)
earliest signs in cardiac conduction system
RBBB
left ant hemiblock
IV/AV blocks
Sick sinus syndrome (SSS - malfunctioning sinus node)
complete heart block
no relationship between P waves + QRS complexes on ECG
severe conduction defect
requires pacemaker
ventricular + atrial arrhythmias
sudden death
major predictors
ventricular dysfunction
non-sustained ventricular tachy on Holter monitoring / ETT (exercise tolerance test)
sustained ventrucalr tachy
resuscitation from cardiac arrest
severe bradyarrhythmia
syncope
less important predictors: late potentials, presyncope
variables with no prognostic value
isolated ventricular extrasystole (Holter)
isolated RBBB
induction of polymorphic VT/VF on PVS (pul valve stenosis)
investigate HR variability, GT dispersion
HF
intracavitary thrombosis
thomboembolic episodes when endocardium damaged
systemic/pul embolic
GI Chagas disease
Megaoesophagus
dilatation
cat face (salivary gland hypertrophy)
dysphagia
regurg
aspiration / pneumonitis risk (esp during sleep when lying flat)
irritative oesophagi's
weightloss + cachexia in severe cases
signs of rupture of oesophagus
increased incidence of cancer of oesophagus
<5% of cases
Megacolon
rarer than megaoesophagus
seen on barium enema
destruction of ANS
like hirschprung's disease
asymmetric distended abdomen
dilated bowel often followed by stricture - chronic constipation
sigmoid volvulus (loop of intestine twists around itself + the mesentery that supports it, resulting in bowel obstruction)
other rare manifestations of chronic chagas
megaureters
megabladder
megagallbladder
bronchiectasis