Transmission

CMV is spread from one person to another, usually by direct and prolonged contact with bodily fluids, including saliva any urine.

CMV is common among healthy children one to three years of age who attend daycare and which can easily be spread among their peers. In the United States, nearly one in three children are already infected with CMV by 5 years of age. CMV is not generally harmful to these children and most do not exhibit signs or symptoms of infection.
 
Contact with the saliva or urine of young children is a major cause of CMV infection among pregnant people, especially those with kids in daycare, daycare workers and childcare providers. People who are pregnant, or plan to become pregnant, who have close contact with young children should practice standard hygiene procedures to reduce their risk of cCMV.

Make sure to wash or use hand sanitizer your hands after:

• Changing diapers
• Feeding a child
• Wiping a child’s nose or mouth

People with an active CMV infection can sometimes shed the virus in their body fluids, such as urine, saliva, blood, tears, semen, and breast milk. The shedding of CMV can happen without any obvious signs and without causing any visible symptoms. Although less common than exposure to a child’s urine or saliva, another possible means of infection is through the bodily fluids of an infected partner (e.g. through kissing, intercourse etc). 

Types of Transmission

Transmission During Pregnancy

CMV can be transmitted through the placenta to a growing pregnancy by a primary, no or a recurrent CMV infection. When a baby catches CMV prior to birth, it is known as a congenital CMV infection. Approximately 90% of all infants who are infected with CMV prior to delivery are born without symptoms of the virus; however, the remaining ten percent (10%) will have varying degrees of abnormalities.
 

Transmission During Birth 

CMV can be transmitted to newborns via contact with maternal genital secretions during delivery or through breast milk. However, infections that occur through these routes usually result in little or no clinical illness in the newborn, unless the newborn is very premature. This does not cause congenital CMV.
 

Transmission During Breastfeeding

There are no recommendations against breastfeeding by mothers who are shedding CMV.  This does not cause congenital CMV. The potential benefits of human milk versus the risk of CMV transmission should be considered when making a decision about breastfeeding for very low birth weight newborns (birth weight <1500 g) by mothers known to have an active CMV infection

Types of CMV Infections

Primary

A primary CMV infection is the first time that someone contracts CMV. People with a primary CMV infection will have no pre-existing immunity to the virus.
 
Primary CMV infection will impact one to four percent (1-4%) of pregnancies and can result in birth defects and developmental disabilities. Usually, there is less risk of CMV-related complications, illness, or abnormalities in babies with mothers infected prior to pregnancy.

Recurrent

A recurrent CMV infection is when a previous CMV infection that has been considered dormant becomes active again. A recurrent infection poses a lower risk of serious impacts to the fetus, as the body has pre-existing immunity to the virus. CMV reactivation can occur when a person's immune system is suppressed due to stress, disease, hospitalizations, or certain therapeutic drugs.
 

Reinfection

Reinfection is a new infection with a different strain of the CMV virus.