Cytomegalovirus retinitis: the neglected disease of the AIDS pandemic.

ytomegalovirus (CMV), a member of the herpesvirus family, was a familiar cause of blindness and death in patients with advanced AIDS in Western countries prior to the introduction of highly active antiretroviral therapy (HAART). CMV retinitis then occurred in roughly one-third of patients with AIDS, and accounted for over 90% of cases of HIV-related blindness (1). Extraocular CMV disease was a major cause of AIDS-related morbidity and mortality (2). CMV retinitis is now clinically infrequent in patients with AIDS in developed countries, thanks to the widespread availability of HAART, although the problem has not disappeared (3,4). Successful fundamentals of management are screening eye examinations in patients with low CD4 counts, and effective anti-CMV treatment with ganciclovir and related compounds, combined with HAART. In developing regions of the world where the HIV/AIDS pandemic is rapidly unfolding, CMV retinitis is a neglected disease, largely undiagnosed and untreated. Workable diagnostic and therapeutic strategies have not yet been defined, and CMV is absent from current and pending World Health Organization (WHO) guidelines for the management of HIV in resource-limited settings. Similarly, the WHO's ambitious "Vision 2020" program, which seeks to provide guidance on the use of ophthalmologic resources until the year 2020, fails to mention CMV retinitis. The scale of the CMV problem in developing regions is still not known, as most cases of CMV retinitis are never diagnosed. Routine retinal examination is rarely performed and the diagnosis may not be considered unless a patient has damaged vision, or even becomes irreversibly blind. Mortality due to extraocular CMV disease is almost impossible to attribute without autopsy, and so is wrongly ascribed, usually to "advanced HIV infection" or tuberculosis. Yet it has been estimated that "between 5% and 25% of all HIV- infected patients in the developing world can be expected to develop this blinding disorder at some point during the course of their illness" (5), leading some to warn of a possible "epidemic of blindness" (6). Recent direct evidence for the substantial scope of this neglected problem comes from a tertiary care ophthalmology center in Chang Mai, Thailand, where in a large consecutive series of referrals, 19% of the cases of bilateral blindness were caused by CMV retinitis, following only cataract as a cause of blindness, and exceeding glaucoma, age-related macular degeneration, and diabetic retinopathy (7). In this article we provide preliminary data describing the problem and suggest possibilities for management of CMV retinitis in resource-poor settings. Our observations are based on the clinical experience from Médecins Sans Frontières (MSF) HIV/AIDS projects in Cambodia, South Africa, Lesotho, Myanmar, Thailand, and China, and on field assessments of four of these programs, and other programs at other locations, by the corresponding author (DH), an ophthalmologist with clinical training and experience with uveitis and CMV retinitis. Epidemiology In developing countries CMV infection is usually acquired in childhood, and nearly 100% of adults are seropositive (8,9,10). Like other herpesvirus infections, CMV may remain latent for life. Overt clinical disease occurs with waning immunity.