the role of transfusions in postoperative cytomegalovirus infections in nonimmunosuppressed subjects cytomegalovirus cmv infection is most frequently observed after open heart surgery with extracorporeal circulation ecc and common after thoracic surgery without ecc and after splenectomies though very rare after other types of surgery studies on open heart patients with ecc carried out in the period 19681979 show an average seroconversion rate of 28 while the febrile mononucleosis syndrome rate would amount to 42 seroconversion is defined as a confirmed increase in the titer of complement fixing cf antibody by a factor of 4 or more the risk of cmv infection is proportional to the quantity of blood transfused fresh blood was initially suspected of being the cause but later investigator have found no difference between fresh and preserved blood seroconversion andor infection risks can be sharply cut by using deleukocyted blood or frozen deglycerolized erythrocytes free of viable leukocytes seroconversion risk increases significantly when cmv cf antibodies are present in transfused blood however the presence of these antibodies in the recipients blood appears to afford protection against seroconversion andor infection except in the case of immunodepressed patients in conclusion cmv febrile mononucleosis syndrome might be due to latent cmv in the transfused blood this transfusion of allogenic blood might induce an immunological reaction that reactivates the latent cmv transmitted to recipient