Immune reconstitution inflammatory syndrome (IRIS) is a frequent complication of HIV-infected patients following initiation of antiretroviral therapy (ART). Although a wide variety of opportunistic pathogens are associated with IRIS, parasites have rarely been reported [1]. We report the first case of IRIS following cryptosporidial cholangitis. A 30-year-old man presented to our emergency room with a long-standing history of severe diarrhea, 25-kg weight loss, as well as epigastric and abdominal pain. He was returning from Turkey where he had drunk contaminated water. Investigation confirmed the presence of Cryptosporidium oocysts in stool; other usual and opportunistic pathogens were absent. HIV-1 serology was positive, CD4 cell count was 120 × 106 cells/l and viral load was 395 160 copies/ml (5.6 log). Renal and hepatic enzymes were normal. An abdominal computed tomography scan showed a 12-mm dilatation of the distal common bile duct. Endoscopic retrograde cholangiopancreatography (ERCP) revealed diffuse mucosal inflammation with fine diffuse nodularities of the duodenum, the common and hepatic bile ducts. Biopsies confirmed the presence of Cryptosporidium oocysts. Sphincterotomy was performed and ART was started with zidovudine, lamivudine and efavirenz. The working diagnosis was HIV-associated cryptosporidial cholangitis. A week later, the patient developed right upper quadrant pain associated with mild cytolysis and cholestasis without associated pancreatitis (Fig. 1). Abdominal studies showed unchanged aspect of the bile ducts and duodenum. This episode was felt to be related to the previous sphincterotomy. Enzymes and symptoms progressively resolved.Fig. 1: Liver enzymes and CD4 cell count over time.Three different entities are presented: cryptosporidial cholangitis on admission (week 0), cholestasis after endoscopic retrogradecholangiopancreatography (weeks 2–4) and immune reconstitution inflammatory syndrome (weeks 8–16). Alk P, alkaline phosphatase; GGT, gamma-glutamyltransferase; SGPT, serum glutamic pyruvic transaminase.Eight weeks after ART initiation, the patient was readmitted with isolated right upper quadrant and epigastric pain with marked elevation of liver enzymes (Fig. 1). Stools samples failed to show Cryptosporidium. The CD4 cell count had markedly increased to 310 × 106 cells/l and viral load decreased to 315 copies/ml (2.5 log). This episode spontaneously resolved during the next 2 months. HIV-associated cholangiopathy is manifested by biliary obstruction due to infection-related strictures [2,3], which historically affected 25% of AIDS patients prior to the advent of ART [4,5]. This entity is usually diagnosed on the basis of clinical features, elevated alkaline phosphatase levels, classic imagery on ERCP [3] and pathogen identification on tissue biopsy (duodenum, ampulla, bile duct or liver). In its acute phase, identification of organisms (Cryptosporidium, Microsporidium, cytomegalovirus or Cyclospora cayetanensis) can be made in approximately 75% of cases [3,6,7] with Cryptosporidium being the most prevalent [6,8]. Disease severity and evolution of biliary cryptosporidiosis in HIV patients largely depends on the immune status of the host. A vulnerable immunity may not efficiently clear a large parasitic burden. For this reason, judicious prescription of ART, instead of antiparasitic therapy, is the preferred initial treatment in cryptosporidiosis. Occasionally, endoscopic sphincterotomy becomes necessary to decompress the biliary system, although the disease can nevertheless progress and become chronic [7,9]. A recent meta-analysis reported a 16.1% incidence of IRIS in HIV-patients starting ART [10]. The following diagnostic criteria for IRIS are generally accepted: HIV patient responding to ART (rapid decrease in plasma viral load by more than 1 log10 or rapid increase in CD4 cell count); atypical inflammatory reaction unexpected in the course of the opportunistic infection; exclusion of others causes that could explain the clinical presentation [11–13]. IRIS can follow any type of opportunistic infection, but has rarely been described with parasites [10,14]. To the author's knowledge, Plasencia et al.[15] reported the only case of an IRIS related to a cryptosporidial infection in an HIV patient with recurring ileitis. Our patient initially presented with a classic case of cryptosporidial cholangitis, confirmed by the presence of Cryptosporidium oocyst on histopathology. The following clinical presentation, 8 weeks after the initial diagnosis, was likely caused by IRIS, as it fits the accepted criteria mentioned earlier: first, the patient had a clear immunologic/virologic response to ART, as confirmed by the quick improvement in CD4 cell count and viral load; second, cryptosporidiosis had resolved completely during that period and was not expected to recur in a HIV patient with markedly improved immunity; third, the timing of the recurrence correlated precisely with the immune reconstitution; and finally, there was no sign of Cryptosporidium or other pathogens on stool sampling. The diagnosis of IRIS is often difficult to pose and was unfortunately delayed in our patient. Had it been suspected earlier, anti-inflammatory drugs or corticosteroids could have been considered. In conclusion, to the authors’ knowledge, this is the first case of IRIS-mediated cholangitis following cryptosporidial infection. Although rare, clinicians should be aware of this possibility following initiation of ART after a documented parasitic infection. Acknowledgements Conflicts of interest There are no conflicts of interest.