Chronic diarrhea caused by Hymenolepis nana in a renal transplant recipient

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To the Editor: The occurrence of parasitic infections of the gastrointestinal tract is well known in renal transplant recipients. Some of the infections manifest as chronic diarrhea and pain in the abdomen; the seemingly easy diagnosis often proves difficult. We describe here a 50-year-old live related renal transplant recipient on prednisolone 10 mg/day, mycophenolate mofetil 1,500 mg/day and tacrolimus 2 mg/day with a baseline serum creatinine of 1.3 mg/dl 3 months posttransplant. He was admitted with a painful abdomen and increased frequency of stools for the past 4 weeks. Stools were watery, occurring four to five times per day, and were without mucus. On examination, the patient was dehydrated with a blood pressure of 106/60 mmHg. Systemic examination was noncontributory except for diffuse abdominal tenderness. Investigations showed hemoglobin 13.5gm/dl, leukocyte count 13,200/mm, blood urea 94 mg/dl, serum creatinine 2.2 mg/dl and tacrolimus trough level 8.5 ng/ml. Blood culture was sterile. Ultrasound of the abdomen was normal. Initial stool microscopy was normal. He was given intravenous fluids, levofloxacin 250 mg/day and metronidazole 500 mg thrice daily. Antibiotics were stopped after 5 days as there was no response. Mycophenolate mofetil was changed to mycophenolate sodium preparation, and his frequency of stool decreased to two to three times/day for the next 3 days, but again his diarrhea worsened. A viral screen, including cytomegalovirus PCR, hepatitis B surface antigen, anti-hepatitis C antibody, IgM anti-hepatitis A and E antibodies, and ELISA for HIV were negative. Stool examination for clostridium difficile toxin was negative. Sigmoidoscopic biopsy showed mucosa with focal extension of chronic inflammation in the lamina propia and mild edema without any evidence of infection or viral inclusion bodies. A repeat stool microscopy showed eggs of Hymenolepis nana (H. nana) in simple wet mount preparation. No other parasite or pathogenic bacteria were found by either stool examination or culture. Nitazoxanide 500 mg twice daily for 3 days was given along with praziquantel 25 mg/kg body weight once. The patient’s condition improved over the next couple of days, and repeat stool samples were negative for H. nana. Renal functions returned to baseline within a week. H. nana can cause troublesome diarrhea in renal transplant recipients. A simple detailed stool analysis can diagnose it. In one of the studies, 4.5% renal transplant recipients were positive for parasitic infections, of which 0.3% had ova related to H. nana [1]. Immunosuppression breaks the balance between the agent and the host. In laboratory models, cyclosporine reduces survival, growth and fecundity in a wide range of protozoans and helminths [2], but this has not been reported with tacrolimus and needs evaluation. However, the role of H. nana as an opportunistic infection is unclear and requires more We certify that a written consent for publication of the case has been obtained from the patient.