Diagnosis of cytomegalovirus infection: a review.

Introduction Cytomegalovirus (CMV) infects between 40100% of adults throughout the world, depending primarily on socio-economic status. However, other relevent factors include the degree and form of sexual activity such that, in the UK, homosexual men have a seroprevalence of 80% compared with 42% of sexually active male heterosexuals.' These individuals may present to genitourinary medicine clinics with CMV-related symptoms, most of whom will be infected with HIV. As a member of the herpes group of viruses, infection with CMV leads to a state of latency with the capacity to reactivate at any time. Primary infection in the immunocompetent is usually asymptomatic but may be associated with a mononucleosis-type illness. Reactivation is of major consequence in those who are immunocompromised in whom it may be associated with retinitis, colitis, pneumonitis or encephalitis, all of which carry significant morbidity.2 The availability of effective anti-CMV therapy has heightened the requirement for rapid, sensitive methods of CMV detection, and these will be discussed in detail. By contrast, serological diagnosis of CMV infection (ie antibody determination) depends on a functional immune system and, we believe, plays little role in CMV diagnosis in the immunocompromised individual. Despite the severe symptomatology associated with CMV, it is important to realise that infection does not equate with disease. Thus, virological evidence of CMV infection must always be interpreted within the clinical context before treatment is considered.