Posttransplantation cytomegalovirus (CMV) disease typically occurs 1-4 months after solid-organ transplantation. The case definition invariably includes unexplained fever for > or =3 days, often with leukopenia. Late and atypical presentation of CMV disease has been rarely reported. Five cases of late and atypical CMV disease in heart (n = 1), liver (n = 1), and kidney (n = 3) transplant recipients occurred within a 4-month period in early 1999. These patients presented at a median of 25 months after organ transplantation (range, 6 months to 22 years). Atypical findings included absence of fever in 3 patients, elevated white blood cell counts in 4 patients, and normal platelet counts in 4 patients. Four patients were at risk for primary CMV infection, and 3 received ganciclovir prophylaxis for 3 months. One patients was treated for rejection, and 2 patients had induction muromonab-CD3 (Orthclone; Orthobiotech). Two of the patients had pulmonary CMV disease, but neither of these patients had hypoxia. Two patients had enterocolitis, one of whom had chronic colitis for a year. These cases may represent a changing epidemiology and clinical presentation of CMV disease in solid-organ transplant recipients in an era of changing immunosuppression and improved CMV disease prevention in the early posttransplantation period.

Among factors associated with bacteremia, use of prophylactic ganciclovir is independently associated with a significant reduction of bacteremia in OLT recipients.

Viral pathogens have emerged as the most important microbial agents having deleterious effects on solid organ transplant (SOT) recipients. Antiviral chemoprophylaxis involves the administration of medications to abort transmission of, avoid reactivation of, or prevent progression to disease from, active viral infection. Cytomegalovirus (CMV) is the major microbial pathogen having a negative effect on SOT recipients. CMV causes infectious disease syndromes, augments iatrogenic immunosuppression and is commonly associated with opportunistic superinfection. CMV has also been implicated in the pathogenesis of rejection. Chemoprophylactic regimens for CMV have included oral aciclovir (acyclovir) at medium and high doses, intravenous and oral ganciclovir, and the prodrugs valaciclovir (valacyclovir) and valganciclovir. CMV prophylactic strategies should be stratified, with the highest-risk patients receiving the most 'potent' prophylactic regimens. Herpes simplex virus (HSV) reactivation in SOT recipients is more frequent, may become more invasive, takes longer to heal, and has greater potential for dissemination to visceral organs than it does in the immunocompetent host. Prophylactic regimens for CMV are also effective chemoprophylaxis against HSV; in the absence of CMV prophylaxis, aciclovir, valaciclovir or famciclovir should be used as HSV prophylaxis in seropositive recipients. Primary varicella-zoster virus (VZV) after SOT is rare and most commonly seen in the paediatric transplant population because of VZV epidemiology. Zoster occurs in 5-15% of patients, usually after the sixth post-transplant month. Prophylactic regimens for zoster are neither practical nor cost effective after SOT because of the late onset of disease and low proportion of affected individuals. All SOT recipients should receive VZV immune globulin after contact with either varicella or zoster. Epstein-Barr virus has its most significant effect in SOT as the precipitating factor in the development of post-transplant lymphoproliferative disorders. Antiviral agents that could be effective are the same as those used for CMV, but indications for and effectiveness of prophylaxis are poorly established. Hepatitis B virus (HBV) and hepatitis C virus (HCV) are important pathogens in the SOT population as indications for transplantation. So-called 'prophylaxis' for recurrent HBV and HCV after liver transplantation is controversial, suppressive rather than preventive, and potentially lifelong. Influenza infection after SOT is acquired by person-to-person contact. During epidemic periods of influenza, transplant populations experience a relatively high frequency of infection, and influenza may affect immunosuppressed SOT recipients more adversely than immunocompetent individuals. Antiviral medications for prevention of influenza are administered as post-exposure prophylaxis to SOT recipients, in addition to yearly vaccine, in circumstances such as influenza epidemics and nosocomial outbreaks, and after exposure to a symptomatic individual during 'flu sea...