Chagas Disease: Creeping into Family Practice in the United States
Although accreditation for this CE/CME activity has expired, and the posttest is no longer available, you can still read the full article.
Expires October 31, 2017
Chagas disease, a parasitic infection, is increasingly being detected in the United States, most likely due to immigration from endemic countries in South and Central America. Approximately 300,000 persons in the US have chronic Chagas disease, and up to 30% of them will develop clinically evident cardiovascular and/or gastrointestinal disease. Here’s practical guidance to help you recognize the features of symptomatic Chagas disease and follow up with appropriate evaluation and management.
NATURAL HISTORY OF INFECTION AND PATIENT PRESENTATION
Acute phase
Infection with the T cruzi parasite is followed by an asymptomatic incubation period of one to two weeks, which is then followed by an acute phase that can last eight to 12 weeks.5 The acute phase is characterized by a large amount of parasites in the bloodstream (see Table 1). The patient is often asymptomatic but can have nonspecific symptoms such as fever, headache, lymphadenopathy, shortness of breath, myalgia, swelling, and abdominal or chest pain.4 Because symptoms during the acute phase are typically mild, many patients do not seek medical attention until they transition into the chronic phase.4 Infants are more likely to experience severe symptoms, including myocarditis or meningoencephalitis, and thus are more likely to present during the acute phase.9
If the patient acquired the infection through an organ transplant, the acute phase symptoms can be delayed, on average, up to 112 days.5 These patients will have more noticeable symptoms, including hepatosplenomegaly, myocarditis, and congestive heart failure. Due to the known risk for transmission through organ transplants, donors are often screened for Chagas disease. Unfortunately, this screening is selective and often inconsistent.5 Therefore, the presence of the previously mentioned symptoms in a person who recently received an organ transplant should raise suspicion of Chagas disease.5
,Chronic phase
Patients not treated during the acute phase will pass into the chronic phase of Chagas disease.5 This may occur due to reactivation of T cruzi infection via immunosuppression.9 At this time, the previously asymptomatic patient will have typical signs and symptoms of chronic disease, along with nodules, panniculitis, and myocarditis.4,9,10 During the chronic phase, parasites are undetectable by microscopy, but the patient can still spread the disease to the vector as well as to others congenitally and through organ donation and blood transfusions.5,9
Patients with chronic T cruzi infection who remain without signs or symptoms of infection are considered to have the indeterminate form of chronic disease. Many patients will remain in the indeterminate form throughout their lives, but between 20% and 30% will progress to the determinate form of chronic disease over years to decades.3 The determinate form is characterized by clinically evident disease and is classically divided into cardiac Chagas disease and digestive Chagas disease.5 Symptoms of the chronic phase depend on the genotype of T cruzi that caused the infection. The AG genotype has a higher incidence of digestive disease.11
Cardiac Chagas disease is believed to occur due to parasite invasion and persistence in cardiac tissue, leading to immune-mediated myocardial injury.5 Chagas cardiomyopathy is characterized by chronic myocarditis affecting all cardiac chambers and disturbances in the electrical conduction system; patients also often develop apical aneurysms. Longstanding cardiac Chagas disease can lead to more serious complications, such as episodes of ventricular tachycardia, heart block, thromboembolic phenomena, severe bradycardia, dilated cardiomyopathy, and congestive heart failure. Patients may complain of presyncope, syncope, and episodes of palpitations. They are also at high risk for sudden cardiac death.5 Patients with cardiomyopathy or cardiac insufficiency secondary to Chagas disease have a worse prognosis than those with idiopathic cardiomyopathy or decompensated heart failure due to other etiologies.12
Less common than cardiac Chagas disease, digestive Chagas disease occurs mostly in Argentina, Bolivia, Chile, Paraguay, Uruguay, and parts of Peru and Brazil; it is rarely seen in northern South America, Central America, or Mexico.5 The parasite causes gastrointestinal symptoms by damaging intramural neurons, resulting in denervation of hollow viscera. Since it affects the esophagus and colon, patients may present with dysphagia, odynophagia, cough, reflux, weight loss, constipation, and abdominal pain.5
