Cytomegalovirus (CMV) is a type of virus that is related to the virus that causes herpes. Like many other viruses, CMV can invade human cells. It can then use those cells to reproduce and spread. If the virus makes many copies of itself, it may disrupt how cells normally work.

In people with a normal immune system, a new CMV infection often has no symptoms. Or it can cause an illness similar to the common cold or mononucleosis with sore throat, swollen lymph nodes, fatigue, and fever. But your immune system keeps the virus in check so it doesn't do any serious harm and the symptoms go away on their own. Very rarely, it can cause major problems in people with a normal immune system.

After infection, CMV stays inactive (dormant) in the body for life. That means that some of your cells still have the virus in them. But the virus isn't actively reproducing or causing symptoms. Sometimes the virus can become active again, especially in people who are sick or have a weak immune system. The infection then spreads to more cells and other parts of the body and symptoms develop.

Infection with CMV is very common worldwide. Most people don't even know they have it. In the United States, infection rates are higher in females and older adults. It's also more common in people from lower socioeconomic backgrounds.

CMV infection is spread from one person to another. The virus is passed on when a person comes into direct contact with an infected person's bodily fluids. These include blood, urine, saliva, semen, tears, and breast milk. Many people are first infected with CMV during childhood. If you're pregnant, you can also pass CMV to your baby.

People who have organ transplants are more likely to get an active CMV infection. Transplants include a solid organ, bone marrow, or stem cell transplant. If you have had a transplant, you will need a medicine to prevent your immune system from attacking the donated organ or stem cells. These medicines are called immunosuppressants because they suppress your immune system. These medicines also make it harder to fight off CMV and other infections.

In the case of CMV infection, most people who develop problems from it after transplant have activated the CMV that has been dormant in their body for many years. Sometimes a person can get CMV after transplant from the transplanted organ, bone marrow, or stem cells. Or they can get it from blood or white blood cell transfusions given when they are sick.

Certain types of transplants may have a higher risk for CMV. These include organ transplants like lung, liver, or kidney. You also have a higher risk for the disease if you didn't previously have the infection but your donor organ came from someone who had it.

You may also have a greater risk of CMV if your immune system is not working as it should. Your specific risk may depend on a number of factors, such as:

• Your age.
• Other health problems you have.
• Whether you have had symptoms of transplant rejection.
• Specific medicines you are taking to prevent rejection.

An active CMV infection may cause a flu-like illness. Symptoms may include:

• Fever.
• Chills.
• Fatigue.
• Muscle aches.
• Swollen lymph nodes.

When CMV invades certain tissues, it can cause serious problems and even death. CMV may also cause problems with a transplanted organ. Most of the time, these symptoms start between 1 and 4 months after the transplant. They may start later if you were taking antiviral medicine at that time. They may also start after you stop taking this medicine.

Before your transplant, your doctor may want to know whether you have an inactive infection with CMV. Your organ donor will also undergo testing for CMV. This information will help make a treatment plan to lower your chances of a CMV infection. A number of different tests might give this information. Your doctor can let you know at this time if you or your organ donor have an inactive CMV infection.

If you don't have a CMV infection, you might become newly infected with it if the donated organ was carrying the virus. If you do have a CMV infection, there is a risk that the virus will reactivate after your transplant.

After your transplant, your doctor may watch you for signs of an active CMV infection. They will ask about any current symptoms and do a physical exam. You may also need other tests. These may include:

• Basic blood work, to check your blood for signs of infection.
• Antibody testing for CMV IgG and IgM.
• Nucleic acid testing, to check for CMV infection.
• Analysis of tissue samples under the microscope, to help diagnose the disease.

If you have an active CMV infection that's causing symptoms, you will need treatment. Common antiviral medicines, such as ganciclovir or valganciclovir, can help. These medicines can help control the virus. But they can't make you completely virus free. Other antiviral medicines may be used to treat CMV that is resistant to ganciclovir or valganciclovir

Based on how serious your illness is, you might take an antiviral medicine by mouth or through an I.V. Your doctor will watch your symptoms and the amount of virus in your body to decide the extent of your treatment. Doctors don't want to give these medicines for a long time. They can cause other side effects and problems.

Many people with active CMV infections often recover quite well, but sometimes an active sickness can cause severe problems. That's especially the case if not treated early.

An active CMV infection can cause major health problems. These include:

• Liver disease (hepatitis).
• Lung infection (pneumonia).
• Infection of the pancreas (pancreatitis).
• Digestive disease (colitis).
• Infection of the brain or spinal cord (meningitis or encephalitis).
• Heart infection (myocarditis).
• Blood clots in a vein (venous thrombosis).
• Bacterial infection of the blood (bacteremia).

These health problems may cause other symptoms. They may also need their own treatments. Sometimes that may involve supportive care in an intensive care unit. These complications can even result in death.

An active CMV infection can also raise your risk for organ rejection. You may need another transplant. Preventive treatments have greatly reduced the number of people who have serious problems from an active CMV infection.

CMV may also raise your risk for certain chronic disorders after the transplant. These include atherosclerosis and diabetes.

Your care team will do everything possible to help prevent an active CMV infection. If your doctor thinks you have a high risk for a new CMV infection or reactivation, they might start preventive antiviral medicines. You may take an antiviral medicine like valganciclovir right after your transplant. You may need to stay on it for some months. The medicine will greatly lower your chance of getting an active CMV infection. But sometimes people get an active CMV infection after stopping these medicines.

If you have never had CMV infection before, your doctors will try to limit the possibility that you pick it up from transplant organs, bone marrow, or stem cells, or from blood or white blood cells that you receive. They will try, if possible, to give you transplants only from CMV negative donors. But sometimes this is not possible.

Other times, your doctor might try to prevent you from having the symptoms of the infection using something called preemptive therapy. In this case, your doctor might want you to have weekly lab tests to see if CMV has become active. In this way, they can find an active infection before you have any symptoms. It allows quicker treatment. That will cut your chance of problems.

Your transplant team also tries to limit your risk for CMV infection by adjusting your immune-suppressing medicines. This is done to find the best balance to maintain your transplanted organ or cells while limiting immune suppression that might increase your risk for CMV.

Contact your doctor now or seek immediate medical care if:

• You have any symptoms of a possible active CMV infection, including:
  • Fever and chills.
  • Fatigue.
  • Nausea and vomiting.
  • Shortness of breath.
  • Chest pain.

• CMV is a virus. It rarely causes long-term problems in people with a normal immune system. In people who have had a transplant, the virus can cause major problems.
• After your transplant, the CMV virus may reactivate. Or you might get a new infection. Both of these can cause symptoms of an active CMV infection.
• An active CMV infection can raise the chance of organ rejection.
• Your doctor may try to prevent an active CMV infection by giving you antiviral medicines or preventing exposing you to CMV.

Tips to help you get the most from a visit to your doctor:

• Know the reason for your visit and what you want to happen.
• Before your visit, write down questions you want answered.
• Bring someone with you to help you ask questions and remember what your doctor tells you.
• At the visit, write down the name of a new diagnosis, and any new medicines, treatments, or tests. Also write down any new instructions your doctor gives you.
• Know why a new medicine or treatment is prescribed, and how it will help you. Also know what the side effects are.
• Ask if your condition can be treated in other ways.
• Know why a test or procedure is recommended and what the results could mean.
• Know what to expect if you do not take the medicine or have the test or procedure.
• If you have a follow-up appointment, write down the date, time, and purpose for that visit.
• Know how you can contact your doctor if you have questions.