Cytomegalovirus

What is it?

Cytomegalovirus (CMV) is one of the herpes group of viruses. It is closely related to the viruses that cause cold sores (herpes simplex) and chickenpox (varicella). The chances of becoming infected with CMV increases with age, with up to 80 percent of people getting the virus by the age of 60. Pregnant mothers can also pass CMV to their unborn child.

Normally, the immune system controls CMV and most people have no symptoms when infected, but some individuals get a disease similar to glandular fever. After infection, the virus remains silently present (dormant) in the body.

People with kidney transplants are more vulnerable to CMV infection because they take drugs to suppress their immune systems and stop organ rejection, which makes it harder to fight off or control viruses. For them, an active CMV infection can cause serious problems which, without prompt treatment, can lead to severe illness and an increased chance of kidney rejection.

Causes

CMV infection occurs when the body’s immune system is unable to control the virus.

People with no prior exposure to the virus who receive a new kidney from a donor who had a dormant CMV infection are at highest risk of getting an active CMV infection. These individuals should be extra vigilant for symptoms such as a bad head cold, flu or diarrhoea and should contact their renal team immediately if they have any concerns.

For other people who have had kidney transplants, a weakened immune system may mean that it can no longer control the virus. So, after many years of lying dormant in the body, the virus can become re-activated.

Difficulties fighting off infection can also cause a person to be re-infected with a different strain (type) of CMV if they come into close contact with someone who has an active CMV infection.

Symptoms

CMV doesn’t usually cause symptoms. But some people can experience flu-like symptoms including:

a high temperature
aching muscles
tiredness
skin rash
feeling sick
sore throat
swollen glands

If you’ve had a kidney transplant and experience any of the following, contact your GP or renal team immediately – or call 999 if your symptoms are severe:

fever and chills
fatigue
diarrhoea
nausea and vomiting
shortness of breath
chest pain

Diagnosis

Blood tests are routinely carried out before a person has a kidney transplant to check if they have a dormant CMV infection. Organ donors are also tested to check for the presence of CMV. This information is then used to create a treatment plan to lower a person’s chances of getting an active CMV infection.

Healthcare providers will also watch out for signs of active CMV infection after a person has had a kidney transplant. They will enquire about any symptoms and check for things like swollen glands, rashes and a high temperature. They may also do further blood tests and analyse tissue samples under a microscope (a biopsy) to confirm whether the virus is active.

Treatment

Transplant units will generally use preventative and/or pre-emptive therapies to minimise the impact of CMV.

To prevent CMV infection, Doctors will prescribe antiviral medicines, taken orally, for around three to six months after a transplant. The amount of time a person will receive this preventative medicine for depends on their risk of getting a CMV infection and the intensity of their immunosuppression treatment. However, sometimes people can get a CMV infection after stopping these medicines.

With pre-emptive therapy, transplant recipients are regularly monitored and are given antiviral medicines as soon as they are judged to be at risk of developing a CMV infection.

If a person does go on to develop a CMV infection their antiviral medication will be given at a treatment dose, or may need to be delivered directly into the bloodstream through an IV line if oral tablets are not possible.

These medicines, combined with the lowering of immunosuppression, can effectively treat CMV and reduce the chance of serious problems.

Disease progression

Preventive and pre-emptive treatments have greatly reduced the number of people who have serious problems from active CMV infection. But, if not treated early, CMV can cause serious problems including:

CMV syndrome (a condition which can cause a number of issues including fever, low white cell count, low platelet count, muscle pain, headache and joint pain)
liver disease (hepatitis)
lung infection (pneumonia)
infection of the pancreas (pancreatitis)
digestive disease (such as gastritis, duodenitis, mouth ulcers, colitis and bloody diarrhoea)
infection of the brain or spinal cord (meningitis or encephalitis)
heart infection (myocarditis)
eye disease which can threaten vision (retinitis)
kidney disease (nephritis)

It can also increase the risk of organ rejection and make transplant patients more susceptible to developing conditions such as diabetes and hardening of the arteries (atherosclerosis).

Resources

If you’ve had a kidney transplant and have any questions or concerns about CMV don’t hesitate to speak to your GP or renal team.

Contact them immediately if you experience any of the following – or call 999 if your symptoms are severe:

fever and chills
fatigue
nausea and vomiting
shortness of breath
chest pain

Reviewed March 2023

Dr Farah Latiff

"I am thrilled to have been awarded a Fellowship to investigate antiviral immunity to cytomegalovirus after kidney transplantation.”

Dr Farah Latiff

How we're helping to protect kidney patients from CMV

If caught early, CMV infections are generally treatable, but new antiviral resistant strains means that research is crucial to support kidney patients in the longer term.

Understanding how CMV affects kidney transplant patients is the first step towards developing new antiviral drugs to protect people from this harmful virus.

Find out how Kidney Research UK funding is enabling Dr Farah Latif to investigate how CMV interacts with the immune system in kidney transplant recipients and how the immune system fights this infection.

Read about the research