Table 3.

Characteristics of infectious congenital hearing loss

Infectious agent	Pathophysiology (presumed)	Prevalence	Unilateral/bilateral	Severity	Progression	Treatment
Toxoplasma gondii	Inflammatory response to the tachyzoite form of T. gondii induces CNS necrosis159	0%160	unknown	unknown	Unknown	The effect of pyrimethamine and sulfadiazine on hearing loss is unknown160, 161
Rubella virus	Direct damage and cell death in the organ of Corti and stria vascularis52	58%42–66%153	Bilateral42	Mild to severe42	Possible	There is no specific treatment available
Cytomegalovirus	Viral labyrinthitis and inflammatory injury 43	15% (industrialized countries)	Unilateral or bilateral	Mild to profound	Common	Ganciclovir or valganciclovir slow the progression and stabilize hearing loss
		33% (developing countries) 162, 163				Established hearing loss is generally irreversible even with antiviral therapy
Herpes simplex virus	Only in association with confounding factors associated with SNHL164	Unknown	Unilateral or bilateral164	Mild to severe	Absent164	The effect of acyclovir155 on hearing loss is unknown
Treponema pallidum	Obliterative endarteritis165	Unknown	Bilateral	Profound	Possible	The effect of intravenous penicillin on hearing loss is unknown156

CNS, central nervous system; SNHL, sensorineural hearing loss