Group proposes screening schedule for infants with congenital CMV infection

About 90% of CMV infants are asymptomatic at birth.

Issue: August 1, 1999

Histology of kidney cells infected with the CMV virus.

Symptoms of CMV include petechial rash and hepatosplenomegaly.

Other symptoms include intracranial calcifications.

CMV patients often present with chorioretinal scars.

TORONTO — Infants with cytomegalovirus (CMV) should receive annual screening examinations because of the high risk of ophthalmologic abnormalities that include severe visual impairment, fundus abnormalities and strabismus.

David K. Coats, MD, reported that while these problems are rare and mild in asymptomatic patients, they are devastating in congenital infections. CMV affects as many as 1% to 2% of all live births in industrialized nations, making it the most common congenital viral infection, he said at the American Association of Pediatric Ophthalmology and Strabismus meeting.

The fetus can acquire the infection from two sources. One is a new maternal infection, and the second is a reactivated maternal infection. While most infants with congenital CMV infection are asymptomatic at the time of birth, as many as 5% to 10% are classified as symptomatic CMV patients.

While children with asymptomatic congenital CMV look completely normal at birth, the situation is quite different for the symptomatic congenital CMV patient who may suffer from a wide spectrum of clinical abnormalities.

Symptoms can include a petechial rash, hepatosplenomegaly, microcephaly and periventricular calcifications. Long term, CMV patients may suffer significant problems due to microcephaly, mental retardation and hearing impairment.

Long-term study

The information on the ophthalmologic manifestations of congenital CMV infection is the product of more than 15 years of work by a large group of researchers known collectively as the CMV Longitudinal Study Group, based in Houston.

Since 1982, and continuing through today, the group has conducted a long-term, longitudinal, prospective study with serial evaluation of ocular, auditory and neurodevelopmental functions. The group has followed 42 symptomatic patients, 83 asymptomatic patients and 21 control patients.

“It’s important to note in the birth data that the symptomatic patients were born more prematurely and significantly lighter than both the asymptomatic and control groups,” Dr. Coats said. “Symptomatic CMV patients have a very high risk of having neurodevelopmental delay, microcephaly and hearing impairment.”

Asymptomatic patients will occasionally suffer neurodevelopmental delay and microcephaly. As many as 17% of the asymptomatic patients will develop hearing impairment that may not develop until the children grow much older.

Visual sequelae

Asymptomatic congenital CMV patients typically have normal vision. The longitudinal study had only one of 83 patients who had mild visual impairment to the level of 20/40 in one eye due to a macular scar.

However, the symptomatic congenital CMV patients have a 22% risk (nine patients) of visual impairment. Among these, 17% had essentially no light perception in both eyes.

Of the nine patients, 22% had a unilateral macular scar, 33% had optic atrophy, and 45% had cortical visual impairment.

“When we go to see patients with congenital CMV infection, we are often asked to rule out chorioretinitis,” Dr. Coats said. “Please realize that optic atrophy and cortical abnormalities are the true causes of visual impairment in these children.”

Fundus abnormalities are common in symptomatic congenital CMV patients, but uncommon in asymptomatic patients. He added that 14% of symptomatic patients had a peripheral chorioretinal scar, and 7% had a macular scar.

“This is about twice as high as had been reported previously with symptomatic CMV patients, but our study group is much larger than previous studies,” Dr. Coats said.

Researchers saw optic atrophy in 7% of patients.

Strabismus also is common in the symptomatic congenital CMV patients and poses yet another threat to their vision. Dr. Coats said that 29% of the symptomatic patients had strabismus, with a single patient in both the asymptomatic and control patient groups having strabismus. Of the 29% of patients who had strabismus, they were fairly equally divided between esotropia and exotropia.

Researchers formed screening recommendations based upon the 15-year review.

Symptomatic congenital CMV patients should receive an examination during the neonatal period followed by an annual screening examination, Dr. Coats said. Asymptomatic patients do not necessarily need an examination in the neonatal period, but probably should have an examination every 2 to 4 years. Both groups should undergo evaluation if problems develop.

For Your Information:

David K. Coats, MD, can be reached at 1102 Bates, Ste. 300 (MC 3-2700), Houston, TX 77030; (713) 770-3234; fax: (713) 770-4776. Dr. Coats has no direct financial interest in any of the products mentioned in this article, nor is he a paid consultant for any companies mentioned.