A 24-year-old woman with no significant medical history presents to the emergency department for progressive shortness of breath. She endorses decreased exercise tolerance as well as intermittent palpitations. She returned from a recent missionary trip to South America 12 months prior where she endorsed eating a local delicacy as well as a period of fevers and eyelid swelling during her stay. Her temperature is 99.1°F (37.3°C), pulse is 95/min, blood pressure is 130/85 mmHg, respirations are 15/min, and oxygen saturation is 97% on room air. Physical exam is notable for a laterally displaced point of maximal impulse as well as a 2/6 diastolic murmur radiating to the axilla. A blood smear is shown in Figure A. Her laboratory results are:

Leukocyte count and differential:
Leukocyte count: 10,000/mm^3
Neutrophils: 57%
Lymphocytes: 30%
Monocytes: 3%
Eosinophils: 9%
Basophils: 1%
Hemoglobin: 13.1 g/dL
Platelet count: 420,000/mm^3

Which of the following is the most appropriate treatment?
Benznidazole
Ganciclovir
Praziquantel
Amphotericin B
Benznidazole
This patient presents with symptoms of heart failure, eosinophilia, trypanosomes on peripheral smear, and a history of recent travel to South America consistent with the diagnosis of Chagas disease. Treatment options for Chagas disease include benznidazole and nifurtimox.

Chagas disease is caused by the parasite Trypanosoma cruzi and is most commonly transmitted by the reduvvid (kissing) bug. The disease is endemic to South America and presents in an acute and chronic phase. The acute phase is characterized by fever, headaches, myalgias, and unilateral eyelid swelling (Romaña’ sign) where the infectious agent has been rubbed into the eye. The chronic phase of the disease is characterized by dilated apical cardiomyopathy leading to conduction abnormalities and valvular dysfunction, megacolon, and megaesophagus. Laboratory testing reveals a peripheral eosinophilia and a peripheral blood smear may reveal the infectious trypanosomes. Treatment is with benznidazole and/or nifurtimox.

Perez-Molina and Molina present the data surrounding the diagnosis and treatment of Chagas disease. They discuss how many cases progress to a chronic state characterized by cardiomyopathy, arrhythmias, and organomegaly. They recommend prompt treatment of the disease to avoid end organ damage.

Figure/Illustration A shows a peripheral blood smear with the trypomastigote form of Trypanosoma cruzi (red circle). Note the anterior location of the dense basophilic nucleus.

Incorrect Answers:
Answer A: Amphotericin B is a potent antifungal that has application in the treatment of multiple fungal infections. It is used as a first-line agent for mucormycosis and cryptococcal meningitis (in addition to flucytosine). Amphotericin B with sodium stibogluconate is used to treat visceral leishmaniasis, a protozoal infection most commonly caused by Leishmania donovani. Side effects can include nausea, vomiting, rigors, fever, hypertension or hypotension, renal dysfunction, and hypoxia.

Answer C: Erythromycin is a macrolide antibiotic that is used in the treatment of bacterial infections. It has a pro-motility effect and can also be used as a gastric pro-motility agent. Potential side effects include gastrointestinal upset, prolonged QT interval, inhibition of the P450 system, and pyloric stenosis in infants.

Answer D: Ganciclovir is a synthetic nucleoside analogue that is mainly used in the treatment of cytomegalovirus (CMV) infections. The most common side effects are bone marrow suppression (granulocytopenia, thrombocytopenia, and anemia) and gastrointestinal upset.

Answer E: Praziquantel is an anti-helminthic used in the treatment of tapeworms and flukes including Echinococcus, Taenia solium (cysticerosis), Schistosoma sp., Clonorchis sinensis (liver fluke), and Paragonimus westermani (lung fluke). Side effects of praziquantel develop due to release of contents from dead parasites and can include gastrointestinal upset, elevated liver enzymes, and dizziness.

Bullet Summary:
Treatment of Chagas disease is with benznidazole or nifurtimox.