By Dr. Grace Centola, Ph.D.
An important topic that often causes confusion among sperm donation recipients is Cytomegalovirus, or CMV. Understanding CMV status is crucial when selecting a sperm donor, and I hope this article will help clarify why this matters.
What is CMV?
CMV is actually part of the family of herpes viruses, sometimes called herpes virus 5 (HHV-5). It’s extremely common—over half of adults in the United States are infected by age 40, and nearly one in three children are infected by age five. Some are even infected during pregnancy. Globally, this prevalence can potentially reach 100% in parts of Africa and Asia, and around 80% in Europe and North America.
Here’s what’s important to understand: once a person is infected, it stays there for life. Most healthy people who are infected by CMV after birth have no symptoms—they don’t even know they have it. Although some may develop symptoms similar to mononucleosis, flu, or a sore throat, no one ever thinks it might be CMV causing these symptoms.
Why CMV Matters in Sperm Donation
The active CMV virus may be spread in bodily fluids of any infected individual, including urine, saliva, blood, and semen. CMV can be passed from one person to another, especially from children, and from mother to baby during pregnancy. This is exactly why donors are tested for CMV during the sperm donation process.
In babies, if the baby is infected, it can cause hearing loss, birth defects, and learning disabilities. CMV can be very clinically significant, especially in people with weakened immune systems, such as those who have had organ transplants, or who have had leukemia or HIV/AIDS.
Understanding CMV Testing: IgG vs IgM
There have been a number of laboratory tests developed that can detect the presence of CMV antibodies. These antibodies develop after infection with CMV.
IgG Antibodies: This is the IgG type of antibody, which develops after an active CMV infection. Persons who have been infected with CMV develop the IgG antibodies, which persist in their body—in their saliva, in their semen—for life. So keep that in mind: once you have CMV, you got it for life.
IgM Antibodies: Here’s where it gets tricky. Shedding of the virus and increases in IgM can occur at any time. A person who was at some point in their life infected with CMV will show a positive IgG. IgM only shows if you’re shedding the virus and, therefore, infectious. You can now pass that virus to someone else.
What the CMV Test Results Mean
The IgG antibody test only indicates that the person has been exposed to CMV virus. It doesn’t tell us if the person is currently shedding the virus. An IgM test that is positive indicates a current or active CMV infection.
- IgG positive, IgM negative: The person has been exposed to CMV at some point but is not currently shedding the virus
- IgG positive, IgM positive: The person is actively contagious and is shedding the virus.
- Both negative: The person has never been infected
Matching Donors and Recipients
Coast to Coast sperm donors who have completed our medical prescreening are tested for CMV as part of the sperm donation process. The results will be shared with your physician so that you can discuss the next steps and risks. While some donors may have been exposed to CMV in the past, it’s best to discuss these issues with your medical provider, so that you can make an informed decision on whether or not a particular donor is a good choice for you.
Frequently Asked Questions About CMV
If a donor is CMV IgG positive, is that unsafe?
No. CMV IgG positivity simply means the donor had CMV in the past, which is very common. Many intended parents are also CMV IgG positive.
Can a CMV-negative recipient use a CMV-positive donor?
This is a personal and medical decision. Some CMV-negative recipients choose CMV-negative donors, while others proceed with CMV-positive donors after counseling. Your fertility provider can help assess your individual risk.
Why don’t sperm banks guarantee CMV-negative donors only?
Because CMV is extremely common, excluding all CMV-positive donors would dramatically limit donor availability and is not medically required. Industry standards focus on identifying recent infection and providing transparency.
Can someone know when they’re shedding CMV?
No. Shedding is usually asymptomatic and unpredictable, which is why screening and informed consent are essential.
What happens once a donor tests positive?
If a donor tests IgG and IgM positive, he will be asked to take a repeat test several weeks later to see if he is still considered IgM positive, meaning that he has an active infection. Your fertility clinic will determine the wait time before he can be tested again.
How is CMV transmitted?
CMV is spread through direct contact with bodily fluids: saliva, urine, blood, semen, vaginal fluids, breast milk, or tears. It can be spread via blood transfusions and from a pregnant person to the fetus. It’s highly transmissible in daycare settings. You can get it through kissing if the person is shedding the virus, through actual intercourse, and through sharing eating and drinking utensils.
Do people know when they’re shedding the virus?
Often, no significant symptoms occur. You may get fever, fatigue, sore throat, or even swollen glands, but may not realize that this caused by CMV.
The shedding of the virus from cells into bodily fluids can occur intermittently, without any signs in your body
How common is CMV?
Half of all people will have had CMV infection by the age of 40, and up to 90% of all people will be infected by the time they reach age 80. One in 200 babies are born with CMV, though only 10% will show symptoms at birth.
What if a baby is born with CMV?
Babies with congenital CMV often appear healthy at birth, with symptoms starting months or years later. The most common late symptoms include hearing loss and delays in development. Newborns may have low birth weight, jaundice, damage to the retina in their eye, a head that is smaller (microcephaly), enlarged spleen, pneumonia, seizures, and developmental and motor delays.
How to Limit CMV Spread
For everyone, to help limit the spread of CMV, practice good hygiene:
- Wash your hands frequently
- Don’t touch your face after handling used tissues or diapers
- Don’t share food, drinks, or utensils with other people—they may have CMV in their saliva and give it to you, or vice versa
The Bottom Line
CMV is a common virus that most people encounter at some point in their lives. While it poses minimal risk to healthy adults, protecting babies from congenital CMV infection is paramount. That’s why we maintain rigorous testing protocols and ensure full transparency about donor CMV status.
Dr. Grace Centola, Ph.D., is a leading expert in reproductive tissue banking with decades of experience in sperm bank operations and donor screening protocols.
Medical Disclaimer: The information provided is for general educational purposes only and does not replace medical advice, diagnosis, or treatment. CMV status and donor eligibility should be reviewed with your physician or fertility specialist to determine what is appropriate for your individual situation.
