A 25-year-old woman comes to the office due to a week of cough and dyspnea. She also reports intermittent, crampy abdominal pain and diarrhea. The patient has no history of respiratory illness or other chronic medical conditions but was recently diagnosed with immune thrombocytopenia that resolved with high-dose glucocorticoid therapy. She does not use tobacco, alcohol, or illicit drugs. She immigrated to the eastern United States from Myanmar 8 years ago, but has not travelled recently. Temperature is 37.2 C (99 F), blood pressure is 120/78 mm Hg, pulse is 88/min, and respirations are 18/min. Physical examination shows scattered wheezes and a nontender abdomen. Laboratory studies reveal eosinophilia, and sputum microscopy is shown in the image below: This patient most likely acquired the pathogen via which of the following modes of transmission?

Question

A 25-year-old woman comes to the office due to a week of cough and dyspnea.  She also reports intermittent, crampy abdominal pain and diarrhea.  The patient has no history of respiratory illness or other chronic medical conditions but was recently diagnosed with immune thrombocytopenia that resolved with high-dose glucocorticoid therapy.  She does not use tobacco, alcohol, or illicit drugs.  She immigrated to the eastern United States from Myanmar 8 years ago, but has not travelled recently.  Temperature is 37.2 C (99 F), blood pressure is 120/78 mm Hg, pulse is 88/min, and respirations are 18/min.  Physical examination shows scattered wheezes and a nontender abdomen.  Laboratory studies reveal eosinophilia, and sputum microscopy is shown in the image below:  This patient most likely acquired the pathogen via which of the following modes of transmission?

Quizplus · Accepted Answer

11ec160b_385d_90ee_9249_8b6b4c862234_MD0001_00 This patient's pulmonary/gastrointestinal symptoms, eosinophilia, and larvae on pulmonary sample indicate strongyloidiasis, a helminth infection endemic to Southeast Asia (eg, Myanmar), Africa, and the Western Pacific. Transmission typically occurs when humans walk barefoot on ground contaminated with human feces. Filariform larvae in the soil penetrate the skin, travel through the bloodstream/lymphatics, and enter the alveoli. They ascend the tracheobronchial tree and are swallowed. The larvae mature into adult worms in the gastrointestinal tract, enter the mucosa of the duodenum and jejunum, and secrete noninfectious rhabditiform larvae into stool for excretion. A few rhabditiform larvae mature into filiform larvae in the gastrointestinal tract and reinfect the host through the intestinal mucosa or perianal skin (autoinoculation). Many patients are asymptomatic because the host immune system keeps the organism in check; however, symptoms may emerge in the setting of immunocompromise due to medications (eg, glucocorticoid therapy) or comorbid illness (eg, cancer, HIV). Common manifestations include the following: Most patients also have peripheral eosinophilia. The diagnosis is typically made when rhabditiform larvae are identified in the stool or, less commonly, sputum. (Choice A) Mosquitos can transmit viral (eg, dengue) and parasitic (eg, malaria) infections. However, these illnesses cause high fever and other systemic symptoms shortly after transmission. Eosinophilia and a nematode (ie, roundworm) in the sputum are more suggestive of helminth infection. (Choice B) Borrelia burgdorferi, a spirochete, is transmitted by Ixodes scapularis tick bite. It causes Lyme disease, which typically presents with a migrating, target-shaped rash that may progress to involve the nervous system or joints. Gastrointestinal/pulmonary symptoms and eosinophilia indicate an alternate diagnosis. (Choice D) Ingestion of oocysts is a common mode of transmission for protozoan parasites (eg, Giardia, Cryptosporidium), which often cause diarrhea and crampy abdominal pain. However, a nematode on sputum microscopy indicates a helminth (ie, parasitic worm) infection; helminths (eg, strongyloidiasis, ascariasis, schistosomiasis) produce eggs (containing multicellular embryos), not oocysts (thick-walled spores). (Choice E) Inhalation of spores can cause a variety of pulmonary fungal infections (eg, histoplasmosis, aspergillosis). Although these pathogens can cause peripheral eosinophilia and pulmonary symptoms, helminths would not be seen in sputum samples. Educational objective: Strongyloides stercoralis is transmitted in tropical/subtropical climates when human skin comes into direct contact with filariform larvae. The larvae penetrate the skin, enter the bloodstream, pass through the lungs, and are swallowed into the digestive system. Common manifestations include linear skin rash and irritative digestive/respiratory symptoms.

A 25-Year-Old Woman Comes to the Office Due to a Week