ATLANTA, GEORGIA — Babies exposed to the Zika virus in the womb should have their hearing tested and monitored regularly, say the authors of a study published today in the Center for Disease Control (CDC) Morbidity and Mortality Weekly Report.
The study evaluated nearly 70 infants in Brazil from November 2015 to May 2016. All the babies had documented microcephaly and confirmed Zika infection. Sixteen of the study group subjects failed the initial hearing screening test and half (8) demonstrated hearing loss at follow-up. By the end of the study, four subjects had permanent sensorineural hearing loss and sensorineural loss was also documented in another subject who’s treatment included ototoxic medication.
Thus, the incidence of sensorineural hearing loss in this small population of infants approached 6% (4 out of 69). By comparison, congenital sensorineural hearing loss reportedly occurs in 4% or less of US births.
Zika virus transmission process. Image courtesy Health Canada
Doctors Need to Monitor Hearing Loss
While hearing loss is a well known side of many congenital infections, including toxoplasmosis, rubella, cytomegalovirus, among others, healthcare professionals should now include congenital Zika virus infection among increased risk factors for hearing loss in children.
“Sensorineural hearing loss should be considered part of the spectrum of clinical findings associated with congenital Zika virus infection, and congenital Zika virus infection should be considered a risk factor for hearing loss in auditory screening programs. Children with evidence of congenital Zika virus infection who have normal initial screening tests should receive regular follow-up, because onset of hearing loss could be delayed and the loss could be progressive.”
In brain scans of babies born with microcephaly, investigators have found lesions and calcification in areas of the brain associated with vision and auditory processing. For these reasons, there have been calls to ensure vision and hearing testing is performed on all babies potentially exposed to the virus.
*Title image courtesy sbs.com.au
