Children impacted by congenital Zika virus should be considered at an increased risk for hearing impairment and late-onset hearing loss, warranting regular follow-up after initial screenings, according to a recent MMWR.
“Hearing loss is a well-established feature of other congenital infections, including cytomegalovirus, rubella, toxoplasmosis, herpes simplex and syphilis,” Mariana C. Leal, PhD, professor of otolaryngology from the Federal University of Pernambuco, Recife, Brazil, and colleagues wrote. “In these syndromes, the hearing loss is sensorineural, usually bilateral, and severe or profound; it is often undetectable at birth, and sometimes it is progressive or fluctuating.”
To determine the relationship between congenital Zika infection and hearing loss in infants, Leal and colleagues conducted a retrospective study that included 70 patients aged 0 to 10 months with a diagnosis of microcephaly and positive Zika laboratory results. Children underwent assessment that included auditory screening and diagnostic testing recommended by the AAP’s Joint Committee on Infant Hearing between November 2015 and May. The researchers considered hearing loss if an infant’s hearing threshold was more than 25 dB normal hearing level. Additional testing was performed 1 month later if an infant’s first test was considered abnormal, and hearing loss was diagnosed upon a second failed test.
Sixteen of the tested infants failed their first screening test in at least one ear. Of those patients, eight failed the second test and underwent frequency-specific auditory brainstem response (ABR). Hearing impairment was defined by ABR in seven infants, including five with sensorineural hearing loss and the others with conductive hearing loss.
Among 63 mothers for whom information was available, 54 said they had a rash during pregnancy. Forty-one mothers said the rash occurred during their first trimester, including four whose infants were diagnosed with sensorineural hearing loss.
“To elucidate the full spectrum of hearing loss in infants with congenital Zika virus infection, testing and follow-up of all children born to women who had Zika virus infection during pregnancy, including infants with no apparent anomalies at birth, is needed,” the researchers wrote.