Internal Medicine

0521779407-20 CUNY1086/Karliner 0 521 77940 7 June 4, 2007 21:22

Trypanosomiasis, American (Chagas’ Disease) 1457

TRYPANOSOMIASIS, AMERICAN (CHAGAS’ DISEASE)

J. GORDON FRIERSON, MD

history & physical

History

■Exposure: Disease most prevalent in South America, especially

Brazil, Bolivia, now less common in Venezuela, Chile, Argentina,

Paraguay, Uruguay, Colombia. Parasite exists in Central America and

Mexico but clinical disease less common. Many mammals, including

dogs serve as reservoir hosts. Transmitted by triatomine bugs, which

live in ceilings and walls of mud and thatched huts. Bite is pain-

less, trypanosomes defecated on skin during feeding, then rubbed

or scratched into wound.

Signs & Symptoms

■Acute phase: usually children, swelling develops at site of bite, some-

times indurated (chagoma). If conjunctiva infected, periorbital tis-

sues swell (Romana’s sign). Then ensues fever, adenopathy, hep-

atosplenomegaly, often meningeal signs. Resolves in 4–8 weeks.

■Indeterminate phase: no symptoms. Parasites settled in myocar-

dium, nerve plexus of esophagus and colon. Lasts 10 or more years.

■Chronic phase: characterized by: a) myocardopathy, with enlarged

heart, congestive heart failure, ventricular aneurysms, and arrhy-

thmias; b) megasyndromes, such as megaesophagus and mega-

colon. Due to destruction of nerve plexus in bowel, these areas lose

motility and dilate producing a baggy, flaccid esophagus or colon or

both, and dysphagia and constipation.

tests

■Basic tests: blood: CBC shows anemia and lymphocytosis in acute

phase, normal later.

■Basic tests: urine: no help

■Specific tests: in acute phase, can see trypanosomes in spun spec-

imen or buffy coat (most sensitive). In indeterminate and chronic

phase, parasites seldom seen, may be detected by xenodiagnosis

(feed triatomine bugs on patient) in about 50%.

■Upper GI or barium enema results are very typical, almost diagnostic

in endemic area.

■Other tests: EKG usually shows RBBB, often other abnormalities,

and rhythm disturbances. PCR useful in detecting parasites in