A 36-year-old immigrant from Peru comes to the office due to difficulty swallowing liquids. He also has difficulty belching. Eating slowly and extending the neck partially relieves his symptoms. The patient has had no fever, weight loss, chest pain, cough, dyspnea, or neurologic symptoms. He has no chronic medical problems and takes no medications. He has been an active smoker for the last 18 years but does not use alcohol or illicit drugs. The patient is afebrile with normal vital signs. BMI is 24 kg/m². On examination, the abdomen is soft, nondistended, and nontender, with no masses or organomegaly. Bowel sounds are normal. Other examination findings are unremarkable. Barium swallow shows a dilated esophagus, and manometry confirms absent peristalsis in the smooth muscle portion of the esophagus. If this patient's symptoms are caused by an infection, which of the following organisms is the most likely cause?

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11ec160b_37f8_18d8_9249_83fb1de42fdc_MD0001_00 This patient who presents with dysphagia and a dilated esophagus has achalasia, which is characterized by the absence of distal esophageal peristalsis and incomplete relaxation of a hypertensive lower esophageal sphincter. It is most often a primary disorder; however, in a patient from Central or South America, secondary achalasia due to Chagas disease should be suspected. Chagas disease is caused by chronic infection with Trypanosoma cruzi, a slender C- or U-shaped flagellated parasite with darkly staining nucleus and kinetoplast. Parasitosis-related inflammation and immune-mediated cross-reactivity between the parasite and the enteric ganglia lead to destruction of the submucosal (Meissner) and myenteric (Auerbach) plexus. Denervation results in uncoordinated smooth muscle activity, increased esophageal tone, and incomplete lower esophageal relaxation. Mechanical dilation (due to obstructed liquids and solids) proximal to the functional obstruction manifests as megaesophagus. Patients classically experience dysphagia progressing from solids to liquids, odynophagia (due to food impaction), difficulty belching, regurgitation, and malnutrition. Other manifestations of Chagas disease can include nonischemic cardiomyopathy and megacolon. In addition, patients are at higher risk for esophageal cancer. (Choices A and C) Immunocompromised patients (eg, advanced HIV) can develop infectious esophagitis. Candida albicans causes exudative esophagitis, usually with concurrent oral thrush. Cytomegalovirus causes ulcerative esophagitis in the distal esophagus. Dysphagia and odynophagia are common with these disorders, but esophageal dilation and motility abnormalities are unexpected, and occurrence in immunocompetent patients is rare. (Choice B) Clostridium botulinum causes botulism, a paralytic disease resulting from neurotoxins that inhibit the release of acetylcholine from presynaptic nerve terminals. Patients develop cranial nerve dysfunction and descending muscular weakness. (Choice D) Helicobacter pylori causes gastritis and peptic ulcer. Typical manifestations include epigastric pain and nausea; however, H pylori does not usually cause esophageal disorders and is unlikely to cause esophageal dilation or absent peristalsis. (Choice E) Schistosoma mansoni is a parasite found in sub-Saharan Africa, the Middle East, South America, and the Caribbean that causes intestinal or hepatic schistosomiasis; this results in gastrointestinal illness (diarrhea, abdominal pain) or portal hypertension and cirrhosis, respectively. Educational objective: Chagas disease is caused by a chronic infection by Trypanosoma cruzi and causes secondary achalasia due to destruction of the submucosal (Meissner) and myenteric (Auerbach) plexus. Other manifestations can include nonischemic cardiomyopathy and megacolon.

A 36-Year-Old Immigrant from Peru Comes to the Office Due