Hyperinfection strongyloidiasis in renal transplant recipients

Abstract

Strongyloidiasis is infection caused by the nematode Strongyloides stercoralis. Chronic uncomplicated strongyloidiasis is known to occur in immunocompetent individuals while hyperinfection and dissemination occurs in selective immunosuppressed hosts particularly those on corticosteroid therapy. We report two cases of hyperinfection strongyloidiasis in renal transplant recipients and document endoscopic and pathological changes in the involved small bowel. One patient presented with features of dehydration and malnutrition while another developed ileal obstruction and strangulation, requiring bowel resection. Oesophagogastroduodenoscopy showed erythematous and thickened duodenal mucosal folds. Histopathological examination of duodenal biopsies revealed S. stercoralis worms, larvae and eggs embedded in mucosa and submucosa. Wet mount stool preparation showed filariform larvae of S. stercoralis in both cases. Patients were managed with anthelmintic therapy (ivermectin/albendazole) and concurrent reduction of immunosuppression. Both patients had uneventful recovery. Complicated strongyloidiasis should be suspected in immunocompromised hosts who present with abdominal pain, vomiting and diarrhoea, particularly in endemic areas.

Figure 1

(A and B) Case 1. Oesophagogastroduodenoscopy. Both images show erythematous and thickened mucosal folds in second part of duodenum.

Figure 2

(A) Case 1. Wet mount stool showing filariform larvae of Strongyloides stercoralis. Detection of S. stercoralis larvae in stool specimens is usually easier in cases of hyperinfection, due to large worm burdens as compared to specimens from immunocompetent hosts. (B) Longitudinal sections of larvae of S. Stercoralis embedded in duodenal mucosa surrounded by mixed inflammatory infiltrate of neutrophils and eosinophils (×200). (C) Duodenal biopsy section showing cross-section of embryonated eggs of S. stercoralis in lamina propria surrounded by inflammation (×400).

Figure 3

(A) Case 2. Plain X-ray film of the abdomen showing a single dilated small bowel loop. (B and C) Oesophagogastroduodenoscopy. The images show erythematous thickened mucosal folds with erosions and granularity in the second part of the duodenum.

Figure 4

Case 2. Resected ileal specimen (A) Gross appearance. Markedly congested, granular mucosa with multiple areas of ulceration and haemorrhage. (B) Light microscopy. Section of Strongyloides stercoralis worm in lamina propria. There is moderate inflammation in vicinity of the parasite (H&E ×400). (C) Light microscopy. S. stercoralis worms are seen embedded in the luminal mucus overlying the mucosa of the small bowel. Abundant mucoid secretions are noted (‘Catarrhal enteritis’; H&E ×200). (D) Light microscopy lymph node. A wandering worm of S. stercoralis is seen in the subcapsular sinus of the lymph node (H&E ×200).