Cytomegalovirus (CMV)

Cytomegalovirus (CMV) is a common virus found in saliva, blood, urine, semen and breast milk. Between 50% and 85% of Americans tested have CMV by the time they are 40.  A healthy immune system keeps it in check.

When the immune system is weakened, CMV can damage the eyes, digestive tract, lungs or other organs of the body.

One of the most common forms of CMV is CMV retinitis. CMV kills the cells in the back of the eye (the retina). Without treatment, it can lead to blindness.

With combination antiretroviral therapy, fewer people with HIV develop conditions due to CMV. Even so, about 5% of people with HIV develop CMV, even with anti-viral therapy.

Symptoms

The signs of CMV depend on the part of the body affected.

CMV retinitis causes moving black spots (floaters), light flashes, distorted vision or blind spots in the vision. CMV colitis causes diarrhea. CMV esophagitis makes swallowing painful and difficult. CMV myelitis causes numbness starting at the base of the spine.  It can move to the legs and make it hard to walk.

In rare cases, CMV causes encephalitis or pneumonia. The signs of CMV encephalitis are like those of other brain infections.  They include personality changes, having a hard time concentrating and headaches. The rare cases of CMV-related pneumonia cause shortness of breath and a dry cough.

Causes and Risk Factors

Cytomegalovirus is a member of the herpesvirus family. It usually isn’t even be noticed in a person with a healthy immune system. When the immune system is weak, CMV can cause diseases that can be life-threatening.

The risk of developing illness due to CMV is highest when the CD4 cell count falls below 100. It is rare in people with a CD4 cell count above that. 

Prevention

Highly active antiretroviral therapy (HAART) is the best way to prevent CMV-related diseases.  HAART builds up the immune system.  This in turn keeps the CMV in check. People who have low CD4 cell counts should get regular eye exams to check for CMV retinitis. 

Diagnosis

A doctor will base a diagnosis on the patient’s symptoms and medical history.  In many cases, however, a tissue sample will be needed to look at under a microscope (a biopsy). This is especially so for CMV colitis or CMV esophagitis. If CMV myelitis is suspected, a small sample of spinal fluid will be tested.

Sometimes the virus can be grown from samples of blood or urine.  This only shows that the virus is in the body.  It doesn’t show whether there is organ disease.
 

Treatment

Treatment of CMV has greatly improved. The first line of defense is HAART.  Once a person’s CD4 count is 100 to 150 and stays there for at least three months, he or she can stop taking anti-CMV drugs.

Drugs used to treat CMV include:

• Ganciclovir, which is used to treat CMV in the retina and other parts of the body. A permanent tube (catheter) is place in the chest so that daily infusions of the drug can be injected into the body. After two weeks, the ganciclovir may be taken as a daily pill. This drug can cause the number of white blood cells to drop as well as nausea, vomiting and low testosterone (a male hormone).
• Foscarnet also treats CMV throughout the body.  It requires a permanent catheter, too. This drug can disturb the balance of sodium in the body and cause dehydration. That may cause kidney problems or failure.
• Cidofovir is used to treat CMV retinitis. It requires infusions into a vein every other week. (A permanent catheter is not needed for this.) This drug can cause kidney problems.  It has to be given with a drug called probenicid to cut the risk of kidney failure.
• Valganciclovir is a whole body therapy.  It can be given through a vein or by pill.