How Does Donor CMV Status Affect Organ Transplant Risk?

Your transplant team uses your donor’s Cytomegalovirus (CMV) status to predict your risk of developing a CMV infection after surgery. The combination of your previous exposure to CMV and your donor’s previous exposure determines your exact risk level and helps your doctors build a customized prevention plan.

The Donor/Recipient Risk Matrix Explained

CMV is a very common virus. Once someone catches it, it stays latent (dormant) in their body for life. To figure out your risk, your transplant team tests both you (the Recipient or “R”) and the organ donor (the Donor or “D”) for CMV antibodies.

A positive (+) result generally indicates the person had the virus in the past and carries antibodies ^[1]. A negative (-) result means they have no detectable antibodies and likely have never had the virus. Doctors combine these results to group patients into three main risk categories:

• Low Risk (D-/R-): Neither you nor the donor has detectable CMV antibodies. The chance of getting a donor-derived virus from the transplant is extremely low, though infection from the community or blood transfusions is still slightly possible ^[1][2].
• Intermediate Risk (R+): If you already have CMV antibodies (either D+/R+ or D-/R+), you are considered intermediate risk. Because your immune system has fought CMV before, it has some memory of how to control it. However, the virus already latent in your own body can reactivate when your immune system is heavily suppressed by anti-rejection medications ^[3][1].
• Highest Risk (D+/R-): The donor has had CMV, but you have not. This is considered the highest-risk pairing for a primary (first-time) CMV infection ^[1][4].

Why D+/R- Is the Highest Risk Scenario

In a D+/R- mismatch, the new organ may carry the latent virus into your body. Because you have never had CMV, your immune system has no natural antibodies or memory cells to recognize it ^[1]. At the exact same time, you must take strong anti-rejection medications that heavily suppress your immune system so your body accepts the new organ.

Without natural defenses, the virus can begin to multiply rapidly. Medical professionals distinguish between two stages of this process:

• CMV Infection (or DNAemia): This means viral DNA is detected in your blood through a PCR test, but you may not feel sick at all ^[5][1].
• CMV Disease: This occurs when the virus causes actual symptoms or tissue damage ^[1].

If left unmanaged, a primary infection can lead to severe CMV disease, especially during the first several months after transplant or after periods of intensified immunosuppression (such as treatment for rejection) ^[6][7]. Complications can include low white blood cell counts, fever, and tissue disease—such as gastrointestinal ulcers or severe diarrhea ^[8]. Furthermore, a CMV infection is associated with an increased risk of organ rejection and other serious complications ^[9][2]. Note: You should never stop or change your anti-rejection or antiviral medications without your team’s direct instruction, as this can be dangerous.

How Your Team Protects You

Because your team uses this risk information, they can choose a prevention and monitoring plan tailored to you. Depending on your specific D/R status, organ type, and kidney function, they will usually use one of two main strategies:

• Preventative Medication (Prophylaxis): You may be prescribed daily antiviral medication (most commonly valganciclovir) for several months after your transplant to suppress the virus while your immune system is at its weakest ^[10][1]. Valganciclovir can sometimes lower white blood cell counts, so your team will monitor your blood closely ^[11]. Recently, a newer antiviral called letermovir was approved specifically for high-risk adult kidney transplant recipients because it is associated with less risk of lowering white blood cell counts compared to valganciclovir ^[12]. Letermovir is not for every patient and can interact with anti-rejection drugs, so your pharmacist and team will carefully review your medications.
• Close Monitoring (Preemptive Therapy): Instead of starting antiviral pills right away, your team will perform regular blood tests (CMV PCR tests) to check for CMV DNA ^[13][11]. If the viral load reaches a specific threshold set by your center’s protocol, they will start treatment to stop the virus before it causes CMV disease ^[1][14].

Even if you receive preventative medication, many centers will continue to monitor your blood using PCR tests after the prophylaxis ends, as the virus can sometimes emerge later ^[4][7].

Symptoms to Watch For

CMV can sometimes cause no symptoms at all, which is why keeping up with your scheduled laboratory tests is critical. However, you should contact your transplant team promptly if you experience:

• Unexplained fever or unusual, profound fatigue
• Severe or persistent diarrhea, nausea, or vomiting
• Abdominal pain or poor appetite
• Shortness of breath or vision changes

Do not assume these symptoms are definitely CMV, as they can have many causes. Always rely on your transplant team for a proper diagnosis and treatment plan.