News

02-04-2017

Despite the current widely circulating and worrying headlines about cytomegalovirus (CMV) infection and pregnancy in many media outlets, it is worth pointing out that although important for pregnant women to be aware of the risk reduction practices they can follow  (as they do for listeria and toxoplasmosis risk) the latest Australia-wide data is from 2014, and has 24 confirmed cases and 2 possible of congenital CMV for the year. The publication is titled, Australian Paediatric Surveillance Unit annual report of uncommon diseases of childhood ( see health.gov.au).

Cytomegalovirus ( CMV) is a common viral infection, 50% of people have been infected by adulthood and up to 85% by 40 years of age. The virus is found in saliva, urine, nasal mucosa, breast milk, vaginal secretions and semen of infected people.The peaks of infection are in children under 2 years and during adolescence. The virus remains alive, but inactive within the body for life. It is rare to get symptoms after the initial infection unless the immune system is weakened by illness or treatments ( reactivation).

Testing for CMV is not routinely recommended for women during pregnancy or for newborn babies ( as per the USA,  UK and Australian Guidelines). CMV testing is currently recommended for pregnant women who develop an acute viral illness or when an US demonstrates a foetal abnormality. Those women planning pregnancy who work in high risk settings such as Child Care may wish to discuss CMV testing with their doctor. A person infected with CMV will develop antibodies in their blood that indicate infection has occurred, either recently or in the past. Interpretation of results can be very complicated in the acutely unwell person,  often can give no immediate answer about the risk to the baby and may require further samples over the next months to diagnose primary or secondary infection with  the assistance of a Specialist in Clinical Microbiology.

Most children and adults with healthy immune systems do not develop symptoms when infected, but can develop an illness similar to glandular fever ( tiredness, sore throat, swollen glands and fever).

Australian statistics estimate that 6 in 1000 infants are born with congenital cytomegalovirus ( CMV) infection, only 1 in 5 infants with congenital CMV infection have long term health problems of varying degrees. ( about 1 in 1000 babies born). The Australian Paediatric Annual Report 2016 has data from the Study commencing in January 1999 to 2014 and gives the number of congenital cytomegalovirus as 273 confirmed cases, with a rate of 6.62 per 100,000 per annum. In 2014, 24 confirmed cases were reported Australia-wide.

The risk of transmission is greatest in the last trimester ( 40-70%), but the risk of complications to the baby is greatest if infection occurs during the first trimester. Congenital CMV occurs when the infection is passed across the placenta from a pregnant woman to her developing baby. There is uncertainty as to whether reactivation of the virus when pregnant causes problems to the woman or her baby.

Most babies with congenital CMV infection have no health problems, about 10% have problems apparent at birth that include, prematurity, liver, lung and spleen abnormalities, low birth weight, microcephaly and seizures.  About 40-60% of infants born with signs of congenital CMV infection at birth develop long term health problems such as hearing loss, vision loss, intellectual disability, microcephaly and seizures. Some babies ( 10-20% of infants with congenital CMV infection) have no signs of congenital CMV at birth, but develop hearing loss later in life.

There is no vaccine available against the virus.

Pregnant women are advised to take steps to reduce their risk of exposure to CMV by:

  • Washing hands often in running water and drying thoroughly ( especially after changing nappies, blowing noses, feeding a young child and handling children's toys) Childcare workers should pay particular attention to good hand hygiene especially after changing nappies and assisting with toileting or blowing noses.
  • Do not share food, drinks, eating utensils or toothbrushes with young children
  • Avoid contact with saliva when kissing children
  • Use simple detergent and water to clean toys, countertops and surfaces in contact with children's urine, mucous or saliva

References

schnhealth.nsw.gov.au ( Sydney Childrens' Hospital)

cdc.gov  ( Centers for Disease Control and Prevention)

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