The menace of CMV disease after small bowel transplantation: Bearer of bad news!

Cytomegalovirus (CMV) is widely distributed in the general population, with seroprevalence rates ranging from 30% to 97% (1). In the absence of prevention strategies, CMV reactivation or new infection typically occurs during the first three months after transplantation. Data on the precise burden in pediatric organ transplant recipients are limited by wide differences in data collection, definitions and reporting. Among five US centers where patients had received two wk of prophylaxis with intravenous ganciclovir with or without CMV-IVIG, 10–20% of pediatric liver transplant patients experienced CMV disease within two yr after transplantation (2). A review of the course of first-time pediatric lung transplant patients indicated that among at-risk subjects, the incidence of CMV viremia and pneumonitis was 29–32% and 20%, respectively, in the first year after transplantation (3, 4). Currently, most available pediatric data were derived from retrospective studies, with the usual limitations, including biases relating to case ascertainment bias, lack of clarity on the factors that are the true triggers for specific interventions and outcomes. The risk of CMV disease is known to be highest in donor-seropositive, recipient-seronegative (D+/R)) recipients (5). This is related to the lack of cellular and humoral immunity to CMV. This applies to a large proportion of pediatric patients, who are often CMV-seronegative at the time of transplantation. Recipients who are CMV-seropositive have a lower risk of CMV disease by virtue of having pre-existing immunity to CMV. The lowest level or risk would be donor-seronegative, recipient-seronegative scenarios (D)R)). While these patients could be at risk if they receive blood or blood products, the risk of transmission of CMV is minimized by the routine use of CMV negative and CMV safe products. In addition to serostatus, several additional factors can influence the risk of CMV by contributing to the overall net state of immunosuppression (6). These include the types and intensity of the immunosuppressive protocols used, patients age, co-morbidities, and the type of organ transplanted. The risk is greatest for lung and small intestinal, followed by pancreas, heart, liver, and kidney transplants. This is likely related to the degree of immunosuppression and the level of the viral load in the transplanted allograft. In the previous issue of the Journal, Florescu and colleagues report incidence, risk factors and outcomes of CMV infection, and disease among a population of pediatric small bowel transplant recipients (7); a population for which data are limited, and one identified as being at increased risk for CMV disease and the potential for adverse outcomes. The authors conducted a retrospective single institution-based study that focused on pediatric and adolescent patients undergoing small bowel or liver-small bowelpancreas transplantation between January 2003 and December 2007. Patients were followed for a minimum of one yr or until they expired. Their CMV prevention strategy involved universal chemoprophylaxis; D+R) subjects received intravenous ganciclovir for three months followed by nine months of oral ganciclovir. Some of these subjects received an alternative regimen consisting of two wk of intravenous ganciclovir followed by valganciclovir for nine months. R+ patients received two wk of IV ganciclovir followed by oral ganciclovir or valganciclovir to complete one yr of antiviral use. All patients received CMV immune globulin for one yr. The therapy of CMV disease or viremia consisted of two wk of IV ganciclovir ‘‘induction’’ at 5 mg/kg twice daily, followed by 2–4 wk of IV ganciclovir ‘‘consolidation’’ at 2.5 mg/kg twice daily or valganciclovir at 14 mg/kg twice daily followed by one month of valganciclovir at 14 mg/kg daily. Pediatr Transplantation 2012: 16: 545–548 2012 John Wiley & Sons A/S.