Treatment training manual

5.10 CMV (cytomegalovirus)

Type of infection

CMV (cytomegalovirus) is a very common viral infection that most people are not aware of.

CMV is common and widespread. Over 50% of the general population, over 60% in intravenous drug users and over 90% in gay men are CMV-positive, In most cases CMV does not have symptoms or cause daily problems.

CMV becomes a serious problem when the immune system is low. This mainly affects people living with HIV who have a very low CD4 count or who have an organ transplant.

CMV becomes a threat when the CD4 count drops below 50 cells/mm3. After HIV treatment (ART), a CD4 count increase to above 50–100 cells/mm3 should stop firther damage from CMV.

Main symptoms

CMV infection can affect many different organs.

  • Eyes (CMV retinitis). This can cause progressive and permanent eye damage. 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 very serious. It can be fatal if CMV reaches the brain and the immune system is unable to control it.


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.


  • 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. This will not control CMV 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 (rarely) 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. Cidofovir 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 the CD4 count is over 100 cells/mm3 for several months – perhaps even over 50 cells/mm3. Otherwise, this difficult treatment is life-long.

Starting HIV treatment (ART), especially at very low CD4 counts, can make the immune system over-react. This can complicate CMV treatment and needs special management.

This overreaction is a form of IRIS (immune reconstitution inflammatory syndrome).


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.


Several drugs for treating CMV are in development. However, this research is not seen as urgent because ART has greatly reduced the number of cases of CMV retinitis.

Last updated: 1 January 2023.