The benefits of new-born screening for congenital Cytomegalovirus (CMV)

According to the CDC, Cytomegalovirus, or CMV, is the most common infectious cause of birth defects in the United States. About 1 out of 200 babies is born with congenital CMV (cCMV).

What is congenital CMV?

CMV is a part of the herpes family of viruses.  It’s a very common infection, and people can contract it at any time.  Many people have no symptoms or effects from having CMV.

If a woman gets CMV for the first-time during pregnancy, it may be passed through the placenta to the baby.  When a baby gets CMV while in the womb, it’s called congenital CMV.

What are the risks of congenital CMV?

According to the CDC, 1 out of 5 babies with congenital CMV will have symptoms or long-term health problems, such as sensorineural hearing loss (SNHL).  This hearing loss may progress from mild to severe during the first two years of life, which is a critical period for language learning.

Over time, hearing loss can affect a child’s ability to develop communication, language, and social skills if not addressed.  Screening newborns for Cytomegalovirus infection could allow early detection of congenitally infected infants and prompt interventions.

What is sensorineural hearing loss (SNHL)?

Sensorineural hearing loss is the most common type of permanent hearing loss, according to the American Speech-Language-Hearing Association.  This type of hearing loss occurs when the inner ear does not develop properly or is injured.

Screening for congenital Cytomegalovirus (CMV) in newborns

Traditionally, the diagnosis of risk of cCMV is focused on the mother.  The identification of newborns at risk is performed indirectly by evaluating the state of the infection in the mother.  Only in children born to mothers at risk, a PCR test is requested to be performed on the urine, as a diagnostic test.  With this approach, about 50% of infected children escape diagnosis.

Recently a study published on the Frontiers of Paediatrics in July 2022, evaluated the clinical usefulness of saliva testing of newborns as screening for cCMV, in association with a quantitative PCR molecular test.  The article describes a multicentre study conducted on 3,150 newborns, in three Italian hospitals.  The article shows that:

  • PCR on the new-born’s saliva allows the identification of newborns affected by cCMV, in the absence of a diagnosis of risk in the mother.
  • Quantitative saliva PCR is an effective test in ruling out cCMV infection.
  • Quantitative PCR in children with positive results allows to discriminate the sick from the positive unaffected ones who will not develop symptoms.
  • Saliva PCR, given its ease of use, rapid turnaround time and high specificity, is the most suitable test for a screening program.

This study shows the benefits of direct diagnosis on the new-born, through molecular tests, to be more effective and reliable in diagnosing cCMV in the child allowing prompt interventions.

Angela Chiereghin, et al.  Universal Newborn Screening for Congenital Cytomegalovirus Infection – From Infant to Maternal Infection: A Prospective Multicenter Study.  Frontiers in Pediatrics, Volume 10, Article 909646, published 6 July 2022, www.frontiersin.org.