LESSONS FROM THE NATURAL-HISTORY OF CYTOMEGALOVIRUS

Background: More than 90% of patients with HIV have been infected at s ome time with cytomegalovirus (CMV) and up to 40% of those with advanc ed HIV will develop CMV disease. The incidence of CMV disease is incre asing but the prognosis for the patient remains poor. Monitoring for C MV: It is therefore important to monitor patients with low CD4(+) coun ts in order to identify those most at risk of developing CMV disease a nd to treat them before the disease becomes established. Polymerase ch ain reaction (PCR) is probably the most effective and sensitive method of detecting CMV and a positive result is predictive for development of CMV disease; more than 80% of patients with CMV retinitis are CMV P CR-positive at the time of diagnosis. PCR can also detect the presence of CMV up to 14 months before the development of retinitis. Treatment of CMV retinitis: In patients with detectable CMV, but no evidence of active infection, pre-emptive treatment with ganciclovir or valaciclo vir has been shown to reduce the risk of developing retinitis in these high-risk patients. Such oral therapy, which is generally better tole rated than intravenous therapy and results in a better quality of life for the patient, is likely to be more effective at this stage whilst viral loads are low. Conclusions: CMV PCR can be used to prospectively monitor patients in order to identify those most at risk of developin g CMV retinitis. If CMV infection is diagnosed early, while viral load s are still low, pre-emptive oral therapy can be instituted which will reduce the chances of developing retinitis in those patients most at risk.