Hippokratia 2003, 7(2):51-58
Organ Transplant Unit, Hippokratio General Hospital, Thessaloniki, Greece
In transplantation of utmost importance are the interactions among immunologically active cells capable of responding to and destroying foreign tissues, the immunosuppressive therapy aimed at controlling these cells and certain infectious agents that are modulated by both factors.
Cytomegalovirus acquisition by humans (HCMV) is more common in lower socioeconomic groups. Natural routes of transmission include intrauterine, perinatal, and horizontal in childhood and in the sexually active people. Other routs of transmission are solid organ transplantation, blood transfusion and semen used for in vitro fertilization.
The post-transplant immunocompromised state provides an environment in which HCMV can exert its full pathogenic potential. HCMV disease is a major cause of morbidity and mortality in solid organ transplantation. It is also associated to an increased risk of opportunistic infections, allograft injury and higher transplantation costs. HCMV infection also seems to increase the risk of acute and chronic rejection of the allograft via immune – mediated vascular injury. Recent evidence suggests that influence of HCMV disease on graft survival is apparent only in patients with zero HLA-DR matches and it calls for new prophylaxis treatment and allocation strategies.
In solid organ transplantation the term “cytomegalovirus infection” refers to asymptomatic HCMV infection and the term “cytomegalovirus disease” refers to symptomatic HCMV infection. Disease manifestations appear most frequently between the end of the 1st and the end of the 4th month after transplantation and include interstitial pneumonitis, hepatitis, gastrointestinal disease, arthritis, chorioretinitis, leukopenia and pyrexial debilitating illness, whose incidences and relative frequencies vary among transplant groups under consideration. In the absence of antiviral prophylaxis, the risk of symptomatic infection is highest in heart – lung recipients (39 %) and lowest in kidney transplant recipients (8%). As many as 70 – 80 % of kidney transplant recipients may show laboratory evidence of HCMV infection after renal transplantation and a significant number develops tissue invasive disease with considerable morbidity and occasional mortality. Recently it has been suggested that within the first three months after transplantation 20 % to 60 % of the recipients develop HCMV disease, with a mortality rate 1% to 4%. Therefore, prophylaxis with antiviral therapy has been recommended in patients at risk.