The clinical relevance of different laboratory tests in CMV diagnosis.

The array of diagnostic tools now available allows not only precise serological determination of past exposure to cytomegalovirus (CMV) infections but also identification of CMV components in blood during viraemia--predictive of CMV disease. Sensitive and rapid identification of CMV components from infected organs from biopsies and body fluids, such as cerebrospinal fluid and bronchoalveolar lavage fluid, is also possible. The polymerase chain reaction (PCR) has become a highly sensitive and specific diagnostic tool that now also can he applied in a quantitative or semiquantitative manner. Non-PCR methods, which amplify the signal rather than DNA itself, are also available as quantitative tests. The antigenaemia assay was the first quantitative measure of CMV load during viraemia. It is useful in the surveillance of CMV in transplant patients as well as for drug efficacy monitoring, and is the method of choice in many laboratories. The use of modern diagnostic tools and subsequent treatment with an appropriate antiviral drug should reduce the number of lethal CMV cases to a minimum.