An unusual cause of pneumonia: Strongyloides stercoralis infection

Article information

Korean J Intern Med. 2023;38(5):781-782

Publication date (electronic) : 2023 June 20

doi : https://doi.org/10.3904/kjim.2023.064

Chun-Jing Lu¹, Jin-Yan Zhang^2,3, Wei-Feng Huang^2,3

¹Department of Blood Transfusion, Women and Children’s Hospital, School of Medicine, Xiamen University, Xiamen, Korea

²Department of Gastroenterology and Hepatology, The First Affiliated Hospital of Xiamen University, School of Medicine, Xiamen University, Xiamen, Korea

³The School of Clinical Medicine, Fujian Medical University, Fuzhou, China

Correspondence to: Wei-Feng Huang, Ph.D., Department of Gastroenterology and Hepatology, The First Affiliated Hospital of Xiamen University, School of Medicine, Xiamen University, Zhenhai RD 55#, Xiamen 361003, China, Tel:+86-18150906129, Fax:+86-05922137708, E-mail: hwf0625@xmu.edu.cn

Received 2023 February 7; Revised 2023 February 14; Accepted 2023 March 3.

A 62-year-old woman presented with a 3-year history of recurrent wheezing, coughing, sputum production, and 10-kg weight loss. Before this hospitalization, she has had repeated hospital admissions due to the above-mentioned complaint. Skin examination revealed no abnormalities. Pulmonary auscultation revealed bilateral wet rales in the lower lung fields. Laboratory values disclosed neutrophilia (10,610/μL), normocytic anemia (7.9 g/dL), hypoalbuminemia (27.4 g/L) and elevated inflammatory markers (C-reactive protein of 41.98 mg/L), without eosinophilia (390/μL). Chest computed tomography (CT) indicated diffuse lung inflammation (Fig. 1A). She was started on antibiotic therapy, but the condition didn’t improve. Due to the history of recurrent unexplained pneumonia and poor response to antibiotic therapy, parasitic infections were suspected. Hence, multiple stool parasite examinations were performed and revealed nematode larvae (Fig. 2A). We also detected nematode larvae in sputum (Fig. 2B, Gram staining) and vomitus specimens (video). Subsequently, strongyloides ELISA blood test was executed and the result was positive. Based on the above findings, the patient was diagnosed with Strongyloides stercoralis hyperinfection syndrome. She was initiated on oral ivermectin at 200 μg/kg once daily for 6 weeks. Fortunately, her condition gradually improved over the following month. A follow-up chest CT scan showed significant improvement of the lesions (Fig. 1B). No recurrences have been observed during 2 years of follow-up.

Figure 1

Chest computed tomography (CT) scan of the patient. (A) Chest CT indicated diffuse lung inflammation. (B) Follow-up chest CT scan showed significant improvement of the lesions.

Figure 2

(A, B) Stool and sputum parasite examinations revealing nematode larvae (400×, gram staining).

Strongyloides stercoralis has the unique ability to replicate within the human host, resulting in a subclinical autoinfection cycle that can persist for decades after exposure [1]. Under some immunocompromised conditions including human immunodeficiency virus infection, immunosuppressive drug, renal transplantations and malnutrition, this can lead to hyperinfection that is characterized by marked increment in the number of worms as well as detection of worms in extraintestinal sites, especially the lungs—hyperinfection syndrome [2], as seen in our case.