David H. Walker, M.D. University of Texas Galveston, Texas
This previously healthy, developmentally normal, 7 month old male child from south Texas had a febrile
illness with coryza three weeks before admission and was treated with antibiotics for otitis media 10 days
before admission. He was admitted to the intensive care unit with cough, pulse 146/min, respirations
50/min, temperature 97.4°F, clear lungs, and hepatosplenomegaly. Admission laboratory data included WBC
22,200/_l, hemoglobin 9.2 g/dl, serum sodium 125 mMol/l, and pO2 76 mmHg. Chest radiographs showed
cardiomegaly and increased pulmonary vascular markings, ECHO showed pericardial effusion and decreased
myocardial contractility, and EKG showed accelerated junctional rhythm.
Treatment included multiple antibiotics, pericardiocentesis, and creation of a pericardial window. The
hospital course was characterized by progressive cardiac failure and death.
Trypanosoma cruzi is endemic in Central and South America with 16-18 million infected persons and 100
million persons living in conditions at risk of infection. Persons become infected by the deposition of
trypanosome-contaminated feces by infested triatomid bugs and its subsequent autoinoculation into the dermis
or onto mucous membranes (e.g., the conjunctiva, where inflammation may be recognized as Romaña sign).
Other modes of infection include infected blood transfusions and mother-to-fetus. Trypanosoma cruzi is
maintained in natural cycles involving more than 100 species of wild and domestic mammals including
opossums, dogs, wood rats, armadillos, raccoons, and cats from the southern US to central Argentina.
Infected animals maintain lifelong parasitemia, an enormous reservoir of the agent. Mainly known as a
chronic infection, Chagas' disease can cause a lethal disease, particularly in infants and young childern,
ususally owing to acute myocarditis and more rarely meningoencephalitis. There have been five patients with
autochthonous Chagas' disease diagnosed in the US, four of whom were children ages 2-3 weeks to 18 months.
The definitive diagnosis of American trypanosomiasis is made by identifying the protozoal parasites. Highly
motile circulating trypomastigotes can frequently be detected in a wet preparation of anticoagulated blood
or buffy coat or in a Giemsa-stained smear. In immunocompromised patients including those with AIDS, the
diagnosis of acute Chagas' disease may be facilitated by microscopic examination of bone marrow, lymph node
aspirate, CSF, or pericardial fluid. Cultivation in special liquid medium or xenodiagnosis, although not
widely available and requiring weeks to complete, are more sensitive than microscopy. Polymerase chain
reaction detection of trypanosomal DNA is highly sensitive and specific if performed properly. The present
case was confirmed by specific PCR of two gene targets of T. cruzi. In the most recently reported case in
an 18 month old child, T. cruzi was identified in two different laboratories by PCR of three gene targets.
This definitive diagnosis led to early, curative treatment with benznidazole. The diagnosis was considered
only because of the mother's pursuit of the identification of an engorged, infected adult female Triatoma
sanguisuga found in the baby's bed. The child never developed antibodies to T. cruzi. Serologic surveys
have demonstrated that low percentages of persons in southern states of the US have antibodies reactive with
T. cruzi. However, lack of availability and standardization of the serologic assays are drawbacks to their
routine use in diagnosing Chagas' disease.
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