Cytomegalovirus, or CMV, is found throughout the world in all geographic and socioeconomic groups, but, in general, it is more widespread in developing countries and in areas of lower socioeconomic conditions. It is a member of the herpesvirus family, which includes the herpes simplex viruses and the viruses that cause chicken pox (varicella-zoster virus) and infectious mononucleosis (Epstein-Barr virus). Infection is common- depending on socioeconomic conditions, prevalence of CMV antibodies in a population ranges from 40 to 100 percent - but serious illness usually occurs only in patients with suppressed immune systems.
CMV is found in body fluids, including urine, saliva, breast milk, blood, tears, semen, and vaginal fluids; and once CMV is in a person's body, it stays there for life. In most healthy adults, infection becomes latent, meaning the virus remains in the body and there is potential for reactivation and recurrent illness – such as in the case of an immunosuppressed patient.
The extent and severity of CMV disease depends on the patient population. In “normal” subjects, it is a viral cause of mononucleosis with few long term sequelae.
In recipients of transplants, CMV is the most frequent viral illness post transplant and the most common cause of viral illness-related death in transplant patient. It is the main infection compromising a successful outcome to SCT, and occurs after most SOT procedures without appropriate preventative therapy. Infection can be “new” or due to reactivation, and severe and/or fatal organ involvement can occur.
There is an increased risk of CMV infection across all transplant types:
Possible clinical manifestations of CMV in transplant patients include: Pneumonia (lung), which is particularly severe and often fatal in SCT; hepatitis (liver), which can be mild or severe, and can be confused with rejection in liver transplant recipients; gastroenteritis (stomach, intestines), which can cause ulcers or bleeding; also can be confused with other infections in the GI tract; retinitis (eye); or meningoencephalitis (brain / spinal cord).
Risk of CMV infection (and subsequent morbidity) may be related to the serostatus of donor and recipient. For solid organ transplant patients (SOT), ‘donor-positive/recipient negative’ transplant represents the highest risk, due to the new primary infection in the recipient. For stem cell transplant patients (SCT), all CMV-positive recipients, regardless of donor status, are at highest risk, presumably due to CMV reactivation in the setting of the intense immunosuppression of SCT.
In newborns, transmission of CMV can cause congenital/perinatal disease that can be fatal. In patients with suppressed immune systems, the ramifications of CMV disease are very significant. According to the CDC:
- CMV is the most common virus transmitted to a pregnant woman's
unborn child
- Approximately 1 in 150 children is born with congenital CMV infection
- Approximately 1 in 750 children is born with or develops permanent disabilities due to CMV
- Approximately 8,000 children each year suffer permanent disabilities caused by CMV
- Congenital CMV (meaning present at birth) is as common a cause of serious disability as Down syndrome, fetal alcohol syndrome, and neural tube defects
In HIV/AIDS, the risk of CMV disease is directly related to severity of HIV disease (i.e., degree of immunosuppression); disease in these patients often is an ocular form of CMV, called CMV retinitis. Up to 30,000 HIV/AIDS patients develop CMV retinitis each year.
Learn more about CMV disease on the CDC website at: http://www.cdc.gov/cmv/