Human cytomegalovirus (HMCV, often known as CMV) is a herpes virus, meaning that it is in the same family as the viruses that cause cold sores, genital herpes, mononucleosis (glandular fever), chickenpox and Roseola Infantum (Exanthema Subitum, Sixth Disease). Most people are infected with CMV at some point in their lives. Some people experience cold-like or glandular fever-like symptoms with CMV, but often no symptoms are registered.
With infection, the herpes virus remains latent in the body, where it can potentially become reactivated. CMV is transmitted by saliva and body fluids, so contagion can take place by kissing or sexual intercourse. It is not possible to be vaccinated against CMV.
Why do we test for CMV?
An infection with CMV is not dangerous. But if a woman gets a primary infection (or rarely: a reactivation) while she is pregnant, there is a risk of the virus being transferred to the fetus. In the majority of these cases the baby is born healthy and unaffected by the infection, but in some instances the child can experience complications in the form of hearing loss, amongst other things, and in rare cases, mental retardation as a result of the infection. With a primary CMV infection or reactivation, the virus can be transmitted via saliva and sperm. It is not known with certainty whether CMV can be transferred via insemination, but we have chosen to test our donors and discard donations if they have been made under a primary CMV infection. Thereby the risk of CMV in the sperm is significantly minimized.
How are the donors tested?
During a primary infection, some of the body’s immune cells form antibodies to fight the virus. These antibodies bind to the virus and therefore, prevent the virus from entering the cell. Antibodies are also known as immunoglobulins, Ig. During a primary infection, immunoglobulins IgM, are formed. After a few weeks, most of the IgM is gone, but there will continue to be immunoglobulins IgG. We test for the presence of IgM and IgG before the release of every unit, and if IgM is tested positive, the unit is discarded.
What should I as recipient use this knowledge for?
If one has, as expectantly pregnant, not had a primary CMV infection (IgM and IgG negative), there is the risk of getting such an infection during the pregnancy. Even though the risk of being infected with CMV through donor sperm can be considered extremely low, one can, as a CMV negative woman, consider ordering sperm from a donor, who has also not had a primary infection. You can see our list of donors who have not yet had a primary CMV infection, here. It is important to emphasize that the probability of getting a CMV infection from transmission routes other than donor sperm, are far higher. If you as recipient test positive for CMV IgG, there is no reason to take the CMV status into consideration when choosing your donor.
If you wish to know more about this topic, we recommend that you look too your doctor or fertility clinic for advice to discuss whether you possibly should consider being screened for CMV before the fertility treatment takes place.