Cytomegalovirus infection after liver transplantation in children

Liver transplantation in an African setting

Liver disease in children in the developing world is a frequent occurrence, which is generally inadequately managed because of lack of resources. However, increasingly, there has been a demand for liver transplantation, where primary medical or surgical therapies have failed. The expertise and infrastructure required for a successful outcome are no different from those in more developed countries; if anything, the challenges are greater. Lack of deceased donors because of cultural and religious factors has driven the use of living donors. Short-term survival has generally been good, but long-term outcomes have rarely been reported. In this article, we review the experience of 2 centers at opposite ends of the continent and share our experience of slightly different settings and show that success can be achieved even in resource-reduced environments.

The efficacy and safety of valganciclovir vs. oral ganciclovir in the prevention of symptomatic CMV infection in children after solid organ transplantation

Routine prophylaxis for CMV with valganciclovir is common in adult recipients but data to support its use in children are scarce. The aim of this study was to compare the efficacy and safety of valganciclovir vs. ganciclovir in a pediatric cohort. We performed a retrospective analysis of 92 children after KTx and/or LTx. All children have received IV ganciclovir for two wk, and then oral ganciclovir (TID; n = 41) before 2004, or valganciclovir (OD; n = 51) thereafter. Treatment was given for three months in R+/D+ or R+/D- recipients and for six months in R-/D+. Patients were followed for one yr post transplant. Both groups were comparable in their demographic and transplant-related history. Symptomatic CMV infection/disease developed in 13.7% vs. 19.5% of valganciclovir and ganciclovir groups, respectively (P-NS). Time-to-onset of CMV infection was comparable in both groups (P-NS); rates of acute allograft rejection were similar in both groups (3.9% vs. 9.8%). Risk factors for CMV infection included young age, serostatus of R-/D+, and allograft from cadaver donor. No significant side effects were noted in both groups. As in adults, valganciclovir appears to be as efficacious and safe as oral ganciclovir. Valganciclovir should be considered as a possible prophylactic treatment for CMV in pediatric recipients of KTx or LTx.

Risk factors for rejection and infection in pediatric liver transplantation

Rejection and infection are important adverse events after pediatric liver transplantation, not previously subject to concurrent risk analysis. Of 2291 children (<18 years), rejection occurred at least once in 46%, serious bacterial/fungal or viral infections in 52%. Infection caused more deaths than rejection (5.5% vs. 0.6% of patients, p < 0.001). Early rejection (<6 month) did not contribute to mortality or graft failure. Recurrent/chronic rejection was a risk in graft failure, but led to retransplant in only 1.6% of first grafts. Multivariate predictors of bacterial/fungal infection included recipient age (highest in infants), race, donor organ variants, bilirubin, anhepatic time, cyclosporin (vs. tacrolimus) and era of transplant (before 2002 vs. after 2002); serious viral infection predictors included donor organ variants, rejection, Epstein-Barr Virus (EBV) naivety and era; for rejection, predictors included age (lowest in infants), primary diagnosis, donor-recipient blood type mismatch, the use of cyclosporin (vs. tacrolimus), no induction and era. In pediatric liver transplantation, infection risk far exceeds that of rejection, which causes limited harm to the patient or graft, particularly in infants. Aggressive infection control, attention to modifiable factors such as pretransplant nutrition and donor organ options and rigorous age-specific review of the risk/benefit of choice and intensity of immunosuppressive regimes is warranted.

Liver transplantation in children

Liver transplantation (LT) is now a standard treatment for children with end-stage liver disease with excellent 1- and 5-year survival. This has been achieved through improvement of surgical techniques and anti-rejection treatment and management. The donor pool for children has been extended by the use of cut-down, split, living-related and, recently, non-heart-beating donor and isolated hepatocyte transplantation. Though the majority of transplanted children enjoy an excellent quality of life, there remain a high number of possible complications, including short-term primary non-function, vascular and biliary problems, bowel perforation, severe rejection, infection, hypertension and long-term renal impairment, chronic rejection, de novo autoimmunity, lymphoproliferative disease and cancer, most of which are related to anti-rejection drug toxicity. Hence, the focus of research for paediatric LT should be induction of tolerance, avoiding long-term immunosuppression and its toxicity.

Colonic stricture mimicking Hirschsprung's disease: a localized cytomegalovirus infection

The diagnosis of congenital cytomegalovirus (CMV) infection is best established by isolating the virus from urine or saliva within the first 2 weeks of life. Detection beyond this point may reflect perinatal acquisition of CMV. Cytomegalovirus is usually transmitted by direct human-to-human contact through vertical or horizontal routes. Infected persons can excrete CMV in urine, saliva, semen, cervical secretions, or breast milk. Because the virus establishes latent infections, blood products and solid organs can also transmit CMV. In the surgical literature, intestinal CMV-infected cells in infants have prevalently been associated with neonatal necrotizing enterocolitis, and only very few cases of primary CMV infection of the gastrointestinal tract of surgical interest in immunocompetent neonates have been reported. We describe a neonate with congenital or perinatal CMV infection with gastrointestinal involvement who developed a colonic stricture and manifested a clinical picture simulating Hirschsprung's disease. The intestinal lesion was a localized segmental CMV infection of the colon in which inflammation dominated the histopathologic finding. Chorioretinitis was also present.

Current status of liver transplantation in children

There are two critical issues on opposite ends of the timeline for patients who are eligible for liver transplantation. On the one hand, the crisis in the cadaveric organ supply makes surviving to transplant ever more risky. On the other hand, patients who receive successful transplants face the consequences of long-term immunosuppression and its potentially life-threatening complications. The donor shortage is forcing difficult decisions that affect all patients who await liver transplantation. It is important to scrutinize carefully the results of all policies that govern allocation and the ethics of the solutions we advocate to ensure that no patient subgroup is being at a disadvantage. Current immunosuppression practices are being challenged by an increasing understanding of the immunologic events triggered by the allograft and the goal to free patients from consequences of a lifetime of immunosuppression. Clinicians can expect, and perhaps require, that new immunosuppressive protocols will address how the planned intervention might be expected to advance the understanding of tolerance mechanisms. As knowledge increases, clinicians can anticipate innovative new immunosuppressive proposals. Calcineurin and steroid-free induction, the use of donor-derived bone marrow infusion, recipient pretreatment, costimulatory blockade, and new antibody induction approaches are all being proposed--often in combination--for clinical trials. Researchers face additional challenges in defining endpoints if the goal is not just the short-term reduction in rejection but the minimization, and eventual discontinuation, of immunosuppressive drugs while maintaining excellent long-term graft function. How much "failure" will be accepted and how will it be defined? How will clinicians interpret liver biopsies if they begin to accept that some lymphocytic infiltrates may be beneficial mediators of the ongoing immune activation necessary for the maintenance of tolerance? How will they adjust immunosuppression practices to the dynamic processes in the immune response that maintain tolerance? Remarkable short-term successes in providing transplants for thousands of children with liver failure have brought these challenges into sharp focus. Clinicians must seek to move the life-giving science of transplantation toward a new goal: providing long lifetimes of excellent graft function with minimal toxicity from immunosuppressive drugs and the hope of freedom from immunosuppression altogether. Pediatric liver recipients, whose grafts have inherent tolerogenic potential and for whom we can anticipate decades of life after transplant, may prove to be an ideal study population to further these goals.

Liver transplantation in children

The results of liver transplantation has improved significantly in the last decade with one year survival figures close to 90% for children with chronic liver disease. This can be attributed to improvement in surgical techniques, better postoperative care and newer immunosuppresive drugs. As a result of this, increasing number of children are referred for transplantation with no significant increase in the number of solid organ donors. The earliest transplants in children were performed using organs from size matched pediatric donors. However, as the pediatric donor numbers were limited, liver reduction techniques were developed to transplant small children before deterioration. Increasing experience with reduced livers led to the development of split liver, living donor and auxiliary liver transplantation. Better management of immunosuppressive drugs and newer agents such as Mycophenolate Mofetil have reduced the incidence of graft loss due to chronic rejection and long-term renal toxicity. The goal for the future will remain to be transplantation without the use of long-term immunosuppression.

Liver transplantation. The pediatric challenge

Successful liver transplantation in a child is often a hard-won victory, requiring all the combined expertise of a dedicated pediatric transplant team. This article outlines the considerable challenges still facing pediatric liver transplant physicians and surgeons. In looking to the future, where should priorities lie to enhance the success already achieved? First, solutions to the donor shortage must be sought aggressively by increasing the use of from split-liver transplants, judicious application of living-donor programs, and increasing the donation rate, perhaps by innovative means. The major immunologic barriers, to successful xenotransplantation make it unlikely that this option will be tenable in the near future. Second, current immunosuppression is nonspecific, toxic, and unable to be individually adjusted to the patient's immune response. The goal of achieving donor-specific tolerance will require new consideration of induction protocols. Developing a clinically applicable method to measure the recipient's immunoreactivity is of paramount importance, for future studies of new immunosuppressive strategies and to address the immediate concern of long-term over-immunosuppression. The inclusion of pediatric patients in new protocols will require the ongoing insistence of pediatric transplant investigators. Third, the current immunosuppressive drugs have a long-term morbidity and mortality of their own. These long-term effects are particularly important in children who may well have decades of exposure to these therapies. There is now some understanding of their long-term renal toxicity and the risk of malignancy. New drugs may obviate renal toxicity, whereas the risk of malignancy is inherent in any nonspecific immunosuppressive regimen. Although progress is being made in preventing and recognizing PTLD, this entity remains an important ongoing concern. The global effect of long-term immunosuppression on the child's growth, development, and intellectual potential is unknown. Of particular concern is the potential for neurotoxicity from the calcineurin inhibitors. Fourth, recurrent disease and new diseases, perhaps potentiated by immunosuppressive drugs, must be considered. Already the recurrence of autoimmune disease and cryptogenic cirrhosis have been documented in pediatric patients. Now, a new lesion, a nonspecific hepatitis, sometimes with positive autoimmune markers, that may progress to cirrhosis has been recognized. It is not known whether this entity is an unusual form of rejection, an unrecognized viral infection, or a response to immunosuppressive drugs themselves. Finally, pediatric transplant recipients, like any other children, must be protected and nourished physically and mentally if they are to fulfill their potential. After liver transplantation the child's growth, intellectual functioning, and psychologic adaptation may all require special attention from parents, teachers, and physicians alike. There is limited understanding of how the enormous physical intervention of a liver transplantation affects a child's cognitive and psychologic function as the child progresses through life. The persons caring for these children have the difficult responsibility of providing services to evaluate these essential measures of children's health over the long term and to intervene if necessary. Part of the transplant physician's our duty to protect and advocate for children is to fight for equal access to health care. In most of the developing world, economic pressures make it impossible to consider liver transplantation a health care priority. In the United States and in other countries with the medical infrastructure to support liver transplantation, however, health care professionals must strive to be sure that the policies governing candidacy for transplantation and allocation of organs are applied justly and uniformly to all children whose lives are threatened by liver disease. In the current regulatory climate that increasingly takes medical decisions out of the hands of physicians, pediatricians must be even more prepared to protect the unique and often complicated needs of children both before and after transplantation. Only in this way can the challenges of the present and the future be met.

Quantitation of peripheral blood cytomegalovirus DNA for monitoring recurrent cytomegalovirus retinitis in pediatric solid organ transplant recipients

Cytomegalovirus (CMV) infection is a major concern following solid organ transplantation, especially in the pediatric population who remain at high risk of primary infection. CMV disease leads not only to increased patient and graft morbidity, but also to increased health care costs. This study describes the usefulness of a quantitative CMV polymerase chain reaction (PCR) technique for monitoring peripheral blood CMV DNA in pediatric recipients of kidney and liver allografts who had recurrent CMV retinitis. The incidence of CMV disease in 28 pediatric transplant recipients was 28.6%, one-half of whom developed retinitis. Two of these patients had recurrent retinitis on cessation of anti-viral treatment. A peripheral blood CMV DNA copy number of > or =500/microg of DNA was associated with recrudescence of the retinitis in these patients. We conclude that the measurement of peripheral blood CMV DNA by PCR is a useful tool for the surveillance of disease resolution and recurrence. This is particularly important in patients with CMV retinitis, who may remain asymptomatic for a period of time, despite recurrences.

Cytomegalovirus enteritis in a premature infant

BACKGROUND/PURPOSE

Up to 2.5% of newborn infants are cytomegalovirus (CMV) positive at birth. Five percent will be symptomatic at birth, including cytomegalic inclusion disease. Symptoms such as hearing loss and mental retardation will ultimately develop in 15%.

METHODS

The authors describe a case of CMV enteritis in a 2.2-kg newborn that presented as necrotizing enterocolitis (NEC) and subsequently developed a colonic stricture.

RESULTS

There are four reports of neonatal CMV enteritis in the nonEnglish-language literature. Cytomegalovirus enteritis has become prevalent among the immunosuppressed pediatric and adult patient population.

CONCLUSIONS

We propose the addition of CMV to the list of pathogens responsible for NEC. A review of neonatal CMV infection is provided.