Type of infection

CMV (cytomegalovirus) is a viral infection.

CMV is widespread (over 50% general population, over 60% in intravenous drug users and over 90% in gay men). It only becomes a problem when the immune system is low – mainly people with HIV or having an organ transplant.

CMV becomes a threat when the CD4 count drop below 50 cells/mm³. CMV usually stops being active if the CD4 count increases above 50-100 cells/mm³ in response to HIV treatment, as the immune system is able to control it again.

Main symptoms

CMV infection can affect many different organs.

• Eyes (CMV retinitis): progressive and permanent loss of sight. Early symptoms include floaters, blind-spots, blurred or dark area of vision, flashing lights and vision loss.
• Eyes: sometimes CMV affects peripheral vision without this being obvious. It is essential that everyone with a CD4 count under 50 has regular eye checks (every 1-3 months).
• Throat: pain while swallowing, chest pain, and hiccups.
• Gut, stomach, bowel, rectum: diarrhoea, bleeding, loss of appetite, weight loss, chest pain.
• Lungs (often with PCP): chest pain.
• Brain and the central nervous system (CMV encephalitis): this is serious. If CMV reaches the brain and the immune system is unable to control it can be fatal.

Diagnosis

CMV retinitis is diagnosed by eye examination. CMV in other organs is diagnosed by tests on a sample from the affected part of the body.

Treatment

• CMV retinitis: immediate treatment is essential, as damage to the eyes is permanent. Ganciclovir and foscarnet are preferred first line treatment. Local treatment (ie just to the affected eye) can be given by a direct injection into the eye or slow release implants. This will not control CMV if it is in other parts of the body.
• Other organs: the same drugs are used to treat CMV in other organs.

The three main treatments are ganciclovir, foscarnet and cidofovir. These drugs are usually given by slow IV delivery, twice a day, starting on the day of diagnosis. When treatment is needed for more than 1-2 weeks, a central line (Hickman line or PortaCath) is usually inserted into a deep vein.

Some drugs are given as tablets, slow release implants or injection directly into the affected part of the body. Valganciclovir (proganciclovir) is a new tablet to replace the tablet form of ganciclovir. Cidovir is given with a second tablet called probenecid to help prevent kidney damage but it is now rarely used because of this toxicity.

ARV treatment that brings CD4 counts back over 50 cells/mm³ is the best medium and long-term treatment.

CMV treatment can be safely stopped once at a CD4 count over 100 cells/mm³ – perhaps even over 50 cells/mm³ – for several months. Otherwise this difficult treatment is life-long.

Starting ARV treatment, especially at very low CD4 counts, can make the immune system over-react – if this happens it complicates CMV treatment and needs special management. This is one form of IRIS (immune reconstitution inflammatory syndrome).

Prophylaxis

There may be a role for prophylaxis with valganciclovir tablets in people with CD4 counts under 50 cells/mm³ who are not responding to HIV treatment. This has to be balanced against the side effects of the drugs and the risk of developing resistance.

In general prophylaxis against CMV is not recommended. It is much better to start or change HIV treatment to increase the CD4 count to a higher and safer level.

Research

Several drugs for treating CMV are in development. This research is not seen as urgent because ARVs have greatly reduced the number of cases of CMV retinitis.