Strongyloides stercoralis hyperinfection

The duodenal biopsy showed patchy mild chronic inflammation, villous edema, villous blunting, and parasites within crypts, consistent with Strongyloides stercoralis infection. Two stool specimens were negative for ova and parasites by trichrome stain; however, Strongyloides serology (IgG) was positive by enzyme-linked immunosorbent assay (ELISA, Quest Diagnostics, Valencia, California). Human immunodeficiency virus (HIV) antibody screening was negative, as was polymerase chain reaction for human T-cell lymphotropic virus (HTLV) I and II DNA. The patient received seven days of oral ivermectin (200 μg/kg daily).

Chronic strongyloidiasis can be asymptomatic or manifest with minimal gastrointestinal or cutaneous symptoms in people living in endemic areas. The decades-long infection begins with filariform larvae of Strongyloides penetrating intact skin. They are transported hematogenously to the lungs, penetrating alveolar spaces. Ascending to the trachea and pharynx, they are swallowed and transported to the small intestine, where larvae become adult female worms producing eggs, which yield rhabditiform larvae. Rhabditiform larvae may be passed in the stool or cause autoinfection of the host by transforming to infective filariform larvae, which can penetrate intestinal mucosa or the skin of the perianal area, once again [1,2]. Thus, the life cycle of the nematode is complete within the human host and may coexist without detection in endemic regions such as Laos, where reported prevalence ranges from 4%–41% [3–5].

Migrants seen at GeoSentinel clinics in all regions of the world have had strongyloidiasis at a rate of about 5% [6]. Detection of larvae remains the gold standard for confirming the diagnosis but has low sensitivity; obtaining three or more successive stool samples for ova and parasites is recommended, as a single stool examination fails to detect larvae in up to 70% of cases. While serologic testing is useful, antibodies can cross react with other nematode infections and do not distinguish between recent and previously treated infections [7]. Real-time polymerase chain reaction (RT-PCR) is a promising diagnostic method that detects Strongyloides DNA in stool samples as a confirmatory method to follow serologic screening in nonendemic areas [8].

Hyperinfection is accelerated by immunosuppression, be it corticosteroids, HIV, HTLV-1, hematologic malignancy, or organ transplantation. Any subject coming from an endemic area must be screened for Strongyloides, at least with serology, before starting any immune suppressant and particularly corticosteroids [9–11]. Gastrointestinal mucosal ulceration may lead to massive hemorrhage and resultant mortality rates as high as 50%–70% [10,12]. Endoscopic biopsy reveals parasites in the gastric crypts or duodenal glands with eosinophilic infiltration of the lamina propria. Ivermectin is the first-line treatment, with a recommended dose of 200 μg/kg orally for one to two days for acute and chronic strongyloidiasis, but longer courses are needed in hyperinfection in the setting of immunosuppression [12–15].

Our patient recovered from strongyloidiasis, but his health was subsequently affected by reactivation of hepatitis B virus, multidermatomal varicella zoster, and disseminated nocardiosis with cutaneous, pancreatic, pulmonary, cerebral, and cerebellar involvement. Remarkably, he recovered from these infections as well and is now maintained on hemodialysis for end-stage renal disease.