Cytomegalovirus, or CMV, is a virus. It is a herpes virus, a family of viruses that also includes the herpes zoster virus (responsible for chicken pox and shingles) and herpes simplex I (responsible for cold sores).

Approximately half of all people in industrialized nations, which includes the United States, are infected with this virus. Almost all gay/bisexual men are infected with CMV and more than 75% of all HIV-positive people carry the virus. However, with potent antiretroviral (ARV) therapy, only a small percentage of these people—mainly those with severely compromised immune systems—will actually develop CMV disease and experience symptoms of this infection.


Being infected with CMV is no reason to panic. CMV is only a threat when the immune system becomes damaged. If your CD4 cell count falls below 50, you’re at a much greater risk of developing CMV disease, particularly CMV retinitis (discussed below). ARV treatment can help protect and repair the immune system. Additionally, preventive therapy (prophylaxis) is available to HIV-positive people who are at risk of developing CMV disease. 

What is CMV disease?

In HIV-infected people, CMV can cause disease in one or several parts of the body. These include:


  • CMV Retinitis: CMV can cause damage to the back of the eye, or the retina. This can lead to blurred vision, blind spots or moving spots, and blindness. This is the most common type of CMV disease in people with HIV. While usually not life-threatening, problems seeing and blindness is usually permanent, even if treatment has been successful.
  • CMV Encephalitis: CMV can also cause damage to the brain. If CMV reaches the brain and the immune system is unable to control it, death can occur within weeks to months. CMV-related brain damage, when less severe, can cause dementia, with confusion, fever and memory problems. The symptoms are very similar to HIV-associated dementia.
  • CMV Radiculopathy: CMV disease of the nerves. This can cause pain or tingling in the limbs, particularly the legs and feet. It can also lead to loss of urinary or bowel movement control.
  • CMV Colitis: CMV disease of the colon is often associated with symptoms of abdominal pain, weight loss, diarrhea, and cramping. Most forms of CMV almost always occur in people with less than 50 T-cells. CMV colitis has been reported in people with higher T-cell counts, even those who are receiving anti-HIV therapy. It is the second most common form of CMV disease (after CMV retinitis).
  • CMV Gastritis: CMV of the upper gut, including the stomach, can lead to symptoms like those seen in patients with CMV colitis.
  • CMV Esophagitis: CMV disease of the throat. Can lead to pain while swallowing, chest pain, and hiccups.
  • CMV Pneumonitis: CMV disease of the lungs. Can lead to difficulty breathing and cough.

What are the symptoms?

Symptoms of CMV depend on the organs that are affected. The symptoms of CMV retinitis are different from CMV disease in the gut.


Some of the symptoms of CMV retinitis include:

  • Floating spots before the eyes
  • Hazy vision, as if looking through a screen
  • Blurred or missing areas of vision

Some of the symptoms of CMV in the gut include:

  • Diarrhea
  • Loss of appetite
  • Fever
  • Blood in the stool
  • Stomach cramps
  • Weight loss
  • Painful swallowing
  • Pain in center of the chest

If you have any of the symptoms, you should contact your doctor immediately.


How is CMV diagnosed?

Again, many people in the United States and elsewhere are infected with CMV. But it only causes disease in those with severely compromised immune systems. And, even in those with damaged immune systems due to HIV, the presence of CMV documented by a blood test does not mean that it will definitely cause active disease.

Diagnosing CMV disease depends on the affected organ. CMV retinitis, for example, can often be diagnosed by an ophthalmologist (eye doctor), simply by looking at the back of the eye. Other forms of CMV, such as CMV encephalitis, esophagitis, and colitis are diagnosed using tissue samples collected from the organ involved.

How is CMV treated?

CMV is treated using powerful antiviral drugs. Like many viruses, CMV cannot be cured (i.e., cleared from the body); it can only be treated to stop it from causing disease. At the same time, treating some forms of CMV—such as CMV retinitis—does not usually reverse damage that has already occurred. It only prevents the disease from worsening.

In most cases, CMV treatment consists of two phases: induction therapy and maintenance therapy. Induction therapy is meant to treat the disease and usually takes two or three weeks. Maintenance therapy is intended to prevent the virus from causing disease again in the future. It used to be that, once CMV treatment was started, it was best to continue with maintenance therapy for life. However, researchers have shown that people with CMV disease who experience a rebound in their CD4 cell counts due to current HIV treatments, can often stop their maintenance therapy, provided that their immune system remains healthy while on HIV drugs. According to the Department of Health and Human Services (DHHS), it is safe to consider stopping CMV maintenance therapy if the CD4 cell count remains above 100 to 150 cells for at least six months.

Treatment depends on the type and severity of CMV involved, as well as a person’s CD4 cell count, his or her ability to adhere to treatment and possible interactions with other medications that are being taken. Antiretroviral therapy is also an important component of CMV treatment—it should be started, or optimized, to keep HIV viral load as low as possible and to boost the CD4 cell count.

The following reviews the preferred (and alternative) CMV treatments recommended by the U.S. Department of Health and Human Services (DHHS), according to OI treatment guidelines published in June 2008:


Retinitis (sight-threatening lesions)

Induction Therapy (preferred):

Ganciclovir implant (Vitrasert; a tiny pellet that contains the CMV drug ganciclovir that is surgically implanted directly into the eye) PLUS twice-daily oral valganciclovir (Valcyte). Continued for two or three weeks.

Induction Therapy (alternative):

  • Intravenous (IV) ganciclovir twice daily for two or three weeks, followed by IV ganciclovir once daily, OR
  • IV ganciclovir twice daily for two or three weeks, followed by oral valganciclovir once daily; OR
  • IV foscarnet (Foscavir) twice daily for two or three weeks, followed by once-daily IV infusions, OR
  • Once-weekly IV cidofovir (Vistide) for two weeks, followed by IV cidofovir given every two weeks. Cidofovir must be given with an oral medication called probenecid to help prevent kidney damage; saline hydration for the eyes is also necessary. However, cidofovir-probenicid should not be used by anyone with an allergy to sulfa-based medications, such as Bactrim.

Maintenance Therapy (preferred):

Oral valganciclovir, 900mg once daily. The ganciclovir implant may need to be replaced after six months if the CD4 count remains below 100.

Maintenance Therapy (alternative):

  • IV ganciclovir once daily, five- to seven-times a week. OR
  • IV foscarnet once daily, OR
  • IV cidofovir (Vistide) given every two weeks, along with probenecid and saline hydration.

(non-sight-threatening lesions)

Induction Therapy:

Twice-daily oral valganciclovir. Continued for two or three weeks.

Maintenance Therapy:

Once-daily oral valganciclovir.


Esophagitis or colitis

Induction Therapy:

IV ganciclovir (Cytovene) OR IV foscarnet (Foscavir) for three or four weeks, or until symptoms improve. Oral valganciclovir may be used if symptoms are not severe enough to interfere with proper absorption of the drug.

Maintenance Therapy:

Generally not necessary, but should be considered after relapses.


Encephalitis or radiculopathy

 Induction Therapy:

IV ganciclovir PLUS IV foscarnet, used until symptoms improve.

Maintenance Therapy:

Oral valganciclovir plus IV foscarnet, continued for life, unless CD4 counts improve.

In people who are diagnosed with CMV retinitis but have not yet started ARV therapy, some specialists may decide to prescribe ARV treatment, in an attempt to halt or reverse worsening eye disease before trying CMV treatment. However, because HIV treatment can take up to six months to achieve a significant improvement in immune system function, both HIV and CMV treatment is recommended for people with larger lesions who have not yet started ARV therapy.

Maintenance therapy for CMV retinitis can be discontinued, providing that there is no active disease and the CD4 count has remained above 100 cells for three to six months. However, it is important to have regular eye examinations, preferably every three months, to ensure that sight-threatening disease doesn’t return, as CMV retinitis can recur even in people with very high CD4 counts.

In some cases, a person may experience immune recovery uveitis (IRU) after first starting antiretroviral therapy. This usually occurs only in people who have very low CD4 counts when they begin ARV therapy, and have very large and rapid gains in CD4 cells. The cause is an over reaction by the newly strengthened immune system to existing CMV. An experienced ophthalmologist can help distinguish IRU from other causes. Symptoms include swelling of the eyes and vision loss. Treatment usually involves corticosteroid drops.


Can CMV be prevented?

Because CMV is a very easy virus to transmit—it can be spread through saliva—there is no easy way to prevent being infected with this virus. However, there are ways to prevent CMV from causing active disease and illness:

Keep your immune system healthy. CMV disease, especially CMV retinitis, can occur once the immune system becomes seriously damaged (less than 100 CD4 cells). Using HIV drugs can help protect the immune system and, as a result, help prevent CMV from causing active disease.

See an ophthalmologist (eye doctor) on a regular basis. If you have a suppressed immune system, you should see an ophthalmologist on a regular basis, usually every three to six months. An ophthalmologist can examine the back of your eyes for any signs of CMV. This is very important, as an ophthalmologist can diagnosis CMV—and recommend treatment—before permanent damage to eyesight occurs.

In the past, experts recommended the use of oral valganciclovir (Valcyte) to prevent CMV in people with CD4 counts below 50 cells. This is no longer recommended by the DHHS, because Valcyte prophylaxis is expensive, can cause CMV to become resistant to the medication and prevent its use as treatment and there is a lack of clinical trial data showing that it prolongs survival in people living with HIV.

Are there any experimental treatments?

If you would like to find out if you are eligible for any clinical trials involving new treatments for CMV, visit, a site run by the U.S. National Institutes of Health. The site has information about all HIV-related clinical studies in the United States. For more info, you can call their toll-free number at 1-800-HIV-0440 (1-800-448-0440) or email

Last Reviewed: January 18, 2016