Among the many etiologies of hearing loss (HL), viral infection of the auditory system is also implicated as the underlying causative factor. Emerging new viral infections, including Zika virus (ZIKV), have been associated with HL in both infants and adults, warranting studies to elucidate the underlying molecular mechanisms that lead to hearing impairment. Early reports of infants with congenital ZIKV syndrome (CZS) estimated a rate of 6% to 9% HL, comparable to some of the other viral causes of congenital HL, although prevalence needs to be further studied.1- 3 In 1 retrospective study, the complete auditory function evaluation in a series of 70 children with microcephaly and laboratory evidence of congenital ZIKV infection revealed that 4 (6%) infants had sensorineural HL (SNHL).1 Click auditory brainstem response (ABR) was performed as a newborn screening test, and frequency-specific ABR was conducted 1 month later to confirm SNHL.1 Another study of 104 neonates with microcephaly and presumed congenital ZIKV infection in Brazil reported 9% HL by otoacoustic emission (OAE) testing.1,2 However, ZIKV testing was not performed because it was not available at the time of the study and incomplete testing for TORCHES (toxoplasmosis, rubella, cytomegalovirus [CMV], herpes, human immunodeficiency virus, and syphilis) was performed. Nevertheless, both reports may be underestimating the incidence of HL because only infants with microcephaly were included. Studies of other congenital infections, such as CMV, have revealed that 8% of infants with CMV who have normal imaging results have HL and up to 25% of infants with CMV eventually have HL.4 Further studies are warranted to determine whether and when infants with ZIKV infection without neurological manifestations develop HL.
Mittal R, Fifer RC, Liu XZ. A Possible Association Between Hearing Loss and Zika Virus Infections. JAMA Otolaryngol Head Neck Surg. Published online October 05, 2017. doi:10.1001/jamaoto.2017.1798
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