Strongyloides-induced Respiratory Failure

摘要

Strongyloides stercoralis is a parasitic nematode particularly prevalent in certain areas such as Southeast Asia. Due to its unique capacity for autoinfection, humans can harbor the parasite for the majority of their lives. The pulmonary migration phase of the parasite's life cycle can imitate asthma and can easily be misdiagnosed. In the immunocompromised patient, a Strongyloides infection can progress to systemic infection and respiratory failure. Systemic steroids, while useful for many clinical conditions, can serve as the immunosuppressive spark for overwhelming Strongyloides dissemination in the undiagnosed patient. Two case histories illustrate this point to two different degrees. The first case involves a seemingly chronic asthmatic whose respiratory ailments resolve when underlying Strongyloidiasis is revealed. The second case involves a steroid dependent woman with SLE whose undiagnosed Strongyloides infection progresses to respiratory failure and death. While difficult to diagnose, subclinical infection should always be suspected in immigrants and visitors from endemic foci. Since early intervention can be life saving, evidence of Strongyloides infection should always be watched for in such high-risk patients undergoing immunosuppressive therapy, particularly those with respiratory complications. Introduction Although the intestinal nematode Strongyloides stercoralis is essentially ubiquitous, it is known to be particularly prevalent in certain parts of the world, such as Southeast Asia, the southeast region of the United States, and the Caribbean. As reported in previous literature, the pulmonary migration phase of Strongyloides infection can present to the physician as an acute asthma attack. Previously asymptomatic strongyloidiasis can also be exacerbated in patients with comorbid pulmonary or autoimmune diseases who are treated with systemic steroids, leading to hyperinfection and respiratory compromise. When missed, treatment aimed at reducing an acute inflammatory condition can be either counterproductive or can allow the infection to build to critical levels. With this in mind, patients exposed to endemic areas with a history of immunosuppression and respiratory complications should be considered for Strongyloidiasis, and here we present two such cases. Report of a Case The first case was a 75 year old Vietnamese male with a five year history of asthma with chronic steroid management for which he has been hospitalized multiple times. In June of 1998, the patient presented to the Pomona Valley Hospital Emergency Department for respiratory distress two days after a ten-day hospital stay for asthmatic bronchitis. He had experienced a sudden onset of dyspnea not relieved by beta-agonist. He denied fever, but did complain of a pruritic rash on his abdomen. Medications at time of admission included prednisone (40 mg daily), theophylline, zafirlukast, albuterol, and ipratropium/triamcinolone acetonide metered dose inhalers. The patient had a fifty-pack*year smoking history, but had not smoked for several years.On physical exam, the patient was in acute respiratory distress, with a blood pressure of 190/94, bilateral expiratory wheezes, and serpiginous erythematous rash over the lower abdomen and proximal thighs. After intubation in the ICU, arterial blood gases revealed a pH of 7.17, pCO2 of 102, and pO2 of 131 on 100% O2 non-rebreather mask. Chest x-ray showed hyperinflation with interstitial infiltration bilaterally (figures 1,2). Laboratory values showed a WBC count of 24,000 with 5% eosinophils, blood glucose of 216, and a theophylline level of 0.5 ug/ml. Sputum Gram’s stain was positive for WBCs and nematode larvae consistent with Strongyloides stercoralis (figure 3). Stool examinations were negative for Strongyloides larvae, but did detect hookworm, either Necator americanus or Ancyclostoma duodenale.