What is cytomegalovirus infection?

Cytomegalovirus (CMV) is a very common virus that can infect people of all ages. It is part of the herpes group of viruses and is similar to the viruses that can cause sold sores (herpes simplex) and chicken pox (varicella).

8 out of 10 people are exposed to CMV by the age of 65, often without knowing it, as it usually causes no or only mild symptoms in healthy individuals.

However, CMV infection can cause serious illness in people who have a weakened immune system. This includes kidney transplant recipients.

When CMV causes an infection in the body for first time it is called a primary infection. The body’s immune system will then make antibodies and other immune cells to protect it against future infection. After the initial infection, the virus will usually remain in the body for life but in an inactive (dormant) state.

The virus can be reactivated if the immune system is weakened, such as after a transplant. The virus can also be transmitted from the donor in the transplant organ.

CMV infection affects around 1 in 5 kidney transplant recipients whose donor was infected and 2 in 100 recipients whose donor was not infected.

Infection usually occurs 4-6 weeks after transplant.

In severe cases, CMV infection can lead to kidney transplant failure.

What are the signs and symptoms of CMV infection?

Many people with CMV who have a normal immune system do not have any symptoms. If symptoms do occur, they are usually mild.

Common symptoms are similar to those of the ‘flu or a cold, and include:

• High temperature
• Loss of energy
• Body aches and pains
• Sore throat

People with a weakened immune system such as those with a transplant are more likely to have more severe symptoms.

These symptoms include:

• Fever
• Night sweats
• Diarrhoea
• Abdominal pain
• Nausea
• Persistent coughing and/or trouble breathing

If it is not treated, CMV infection can cause serious problems including:

• kidney transplant failure
• meningitis
• liver disease
• pneumonia

What causes CMV infection ?

CMV is spread through body fluids, including blood, saliva, urine, and breast milk. It can only pass from person to person through close contact, such as kissing or sharing utensils, and from mother to baby during childbirth. Most people are infected with CMV in this way in childhood and either do not have any symptoms or experience only a mild flu-like illness.

In a small number of cases, CMV is transmitted through organ transplant. It is therefore known as a donor derived infection and you may become infected through a kidney and/or pancreas transplant. Your healthcare team will explain the risks of infection, the attempts taken to prevent it and how you will be monitored after transplant.

It is recommended that all organ donors and recipients are screened for CMV before transplant.

CMV infection is of particular concern to transplant patients because of their:

• Weakened immune system due to anti-rejection drugs. Post-transplant, patients take medications to suppress their immune system to prevent organ rejection. This makes them more susceptible to infections, including CMV.
• Risk of CMV disease: CMV can reactivate after lying dormant in the body if you have been infected before transplantation or it can be newly contracted. In both cases, CMV infection can cause symptoms ranging from mild flu-like illness to severe organ damage, especially in the transplanted kidney.

How is CMV infection diagnosed?

CMV infection is diagnosed by blood tests.

Before transplantation, your healthcare team will test you and your donor for antibodies to CMV. These blood tests will help to determine your risk of contracting CMV post-transplant.

After transplantation, you will be monitored with a blood test called a CMV PCR to check for infection. This will allow your healthcare team to start treating the virus if it does occur before it causes any severe symptoms.

Does CMV infection affect other parts of the body?

In severe cases, CMV infection can affect other parts of the body including the brain, liver, heart and eyes.

Does CMV infection run in families?

CMV infection can pass from mother to baby during childbirth.

How is CMV infection treated?

You may be prescribed antiviral drugs to prevent CMV infection after your transplant. This is usually an antiviral drug called valganciclovir and it is given for 3-6 months.

If you do develop CMV infection, antiviral medications will be used to treat the infection. Sometimes, the dose of your immunosuppressive medication may need to be adjusted.

A vaccine for CMV is currently being developed.

You can help prevent or minimise the effects of CMV infection by:

• Taking your medication as instructed by your transplant team
• Attending your post-transplant check-ups. Regular monitoring helps detect CMV early.
• Telling your transplant team if you develop any symptoms of CMV infection, even if they are only mild.

Contact your transplant team for more advice and information.

Where can I get more information or support about CMV infection?

We are not aware of any UK-based support groups for CMV infection. If you know of any CMV infection patient groups, please let us know so we can share their details.

Publication date: 09/2025

Review date: 09/2028

This resource was produced according to PIF TICK standards. PIF TICK is the UK’s only assessed quality mark for print and online health and care information. Kidney Care UK is PIF TICK accredited.