Strongyloidiasis stercoralis can cause disease when larvae invade the human body through the skin or mucosa and can also infect a host when the host ingests its eggs.^[1] Strongyloidiasis lacks characteristic manifestations, and its clinical symptoms are related to the immune response of the host and the degree of infection. Immunodeficient patients with underlying disease or who are receiving long-term corticosteroid treatment are more prone to developing severe disease.^[2] The present study reports a case of Strongyloides stercoralis-induced sepsis and acute respiratory distress syndrome (ARDS) in a patient with Guillain-Barré syndrome.

This case involved a 51-year-old male who was admitted to the isolation ward for COVID-19 at Guangdong Provincial People’s Hospital on March 14, 2020. The patient had a history of Guillain-Barré syndrome and long-term use of corticosteroids. Ten days before admission, the patient experienced abdominal pain, vomiting, and diarrhea. Fever and shortness of breath developed eight days later. The patient was subsequently admitted with a diagnosis of sepsis, sepsis-associated lung injury, acute gastroenteritis, and Guillain-Barré syndrome.

The patient was conscious, with temperature 39.4 °C, heart rate 129 beats/min, respiratory rate 30 breaths/min, and blood pressure 142/76 mmHg (1 mmHg=0.133 kPa) at admission. The results of laboratory examinations were as follows: white blood cell (WBC) count 8.58×10⁹/L, neutrophil (NEUT) count 7.70×10⁹/L, eosinophil count 0.01×10⁹/L, platelet (PLT) count 144×10⁹/L, procalcitonin (PCT) level 3.08 ng/mL, interleukin-6 (IL-6) level 265.0 pg/mL, and C-reactive protein (CRP) level >200 mg/L. Tests for influenza A/B virus antigens and SARS-CoV-2 nucleic acid were negative. Blood gas analysis revealed the following parameters: pH 7.3, oxygen partial pressure (PaO₂) 61.4 mmHg, carbon dioxide partial pressure (PaCO₂) 43.1 mmHg, oxygen saturation (SaO₂) 91%, actual bicarbonate (HCO₃^-) level 22.4 mmol/L, lactic acid level 2.5 mmol/L and oxygenation index 123 mmHg. Chest computed tomography (CT) revealed multiple patchy shadows in both lungs with a gravitational distribution (Figure 1 A-C). His organ function parameters were as follows: N-terminal proBNP (NT-proBNP) level 4903.0 pg/mL, hs-cTnT level 21.0 pg/mL, total bilirubin level 25.3 µmol/L, conjugated bilirubin level 7.8 µmol/L, albumin level 26.30 g/L, and creatinine level 44.26 µmol/L. His intracranial pressure was 149 mmHg. Cerebrospinal fluid (CSF) examination revealed white blood cells 22×10⁶/L, red blood cells 0, glucose 6.92 mmol/L, chloride 122.1 mmol/L, and microprotein 808 mg/L. High-throughput sequencing of the CSF revealed that there were no pathogenic bacteria. Cranial magnetic resonance imaging (MRI) and diffusion-weighted imaging (DWI) were normal.

The diagnosis was initially unclear. The results of the serum galactomannan (GM) assay were 0.36 µg/L (day 2), <0.25 µg/L (day 7) and <0.25 µg/L (day 11). Cultures of bronchoalveolar lavage fluid were obtained during hospitalization. Stenotrophomonas maltophilia was detected only on day 21, and the rest of the samples were negative. Due to the COVID-19 epidemic and the rapid progression of pulmonary imaging, empirical anti-infective and antiviral therapies were administered. Deworming was not initiated until high-throughput sequencing was completed. High-throughput sequencing of bronchoalveolar lavage fluid revealed the presence of cytomegalovirus (sequence number 5) and Strongyloides stercoralis (sequence number 210865). High-throughput sequencing of the blood did not reveal Strongyloides stercoralis but did reveal cytomegalovirus (sequence number 6), Staphylococcus (sequence number 6), Staphylococcus aureus (sequence number 2), and Escherichia coli (sequence number 4). However, blood bacterial cultures were negative, and Strongyloides stercoralis was subsequently found microscopically in sputum, bronchoalveolar lavage fluid, gastric juice (Figure 2, video of the supplementary file), stool, and urine. Therefore, the diagnoses were amended to strongyloidiasis, sepsis, ARDS, and Guillain-Barré syndrome. Then, 0.4 g of albendazole twice a day was administered as a deworming treatment. Comprehensive treatment, including maintaining electrolyte balance and hemodynamic stability, mechanical ventilation, nutritional support therapy, etc., was administered in the intensive care unit (ICU). After a full course of deworming treatment, no worms were found. The laboratory test results and pulmonary imaging findings improved after deworming treatment (Table 1, Figure 1 D-F). The patient was cured and recovered well after 6 months of follow-up.

The onset of the disease was characterized by abdominal pain, diarrhea, fever, and shortness of breath. The diagnosis of strongyloidiasis was based on the observation of larvae. The patient was immunocompromised, which was a risk factor for severe infection. The patient had sepsis and ARDS at admission and was critically ill. Fortunately, he was cured after regular deworming treatment and recovered well.

With an effective immune response of the host, Strongyloides stercoralis can be eliminated without clinical symptoms. However, if the parasites are not cleared from the body, patients present with persistent chronic infection. Larvae can reach the brain, liver and lungs, and patients often die of organ failure. It is especially common in patients with long-term use of corticosteroids and immunosuppressants.^[1] The patient in this case had a long-term history of corticosteroid use and presented with respiratory failure.

The means of diagnosing Strongyloidiasis stercoralis is to identify the pathogen in the patient’s feces, saliva, gastric juice, urine, and CSF. In this case, larvae were found in bronchoalveolar lavage fluid, gastric juice, urine, and stool. An examination of the patient’s blood revealed that the eosinophil count was increased. The treatment of strongyloidiasis should include early, sufficient and full-duration deworming treatment. The first-line drug for the treatment of infection caused by Strongyloides stercoralis is ivermectin, and the cure rate is close to 80%.^[3] However, it is difficult to find ivermectin in China, and most patients are treated with albendazole. Albendazole at a dose of 0.4 g twice a day for 3 to 7 d has been shown to be effective as a deworming treatment.^[4] In this case report, albendazole did not work because of gastric paralysis in the early stage of the disease. Therefore, a nasointestinal tube was placed, and the dose of albendazole was increased to 0.6 g twice a day. After a full course of deworming treatment, no live worms were found. The patient was cured and recovered well.

This study has several limitations. If the following tests, such as contrast-enhanced CT and biopsy of the lungs, the actual number of natural killer cells, the number of CD4⁺ T cells, the number of CD8⁺ T cells, and the CD4⁺/8⁺ ratio, were completed in time, the accuracy of diagnosis would increase.

In summary, strongyloidiasis is a rare disease, and the clinical symptoms are diverse, often leading to misdiagnosis. Repeated examinations should be performed for patients suspected of having strongyloidiasis. Adequate deworming treatment should be given to improve outcome. This case increases the understanding and awareness of strongyloidiasis, contributing to timely diagnosis and proper treatment.

Funding: This study was supported by the Medical Scientific Research Foundation of Guangdong Province (A2022506), Natural Science Foundation of Guangdong Province (2023A1515010267) and Cerebrovascular Disease Youth Innovation (Z-2016-20-2201).

Ethical approval: The patient gave the informed consent.

Conflicts of interest: None.

Contributors: All authors contributed significantly to the writing and revision of this manuscript and approved the final version.