Table 2.
Congenital infections associated with acquired hearing loss
| Infectious agent | Type (mode of acquisition) |
Transmission | Epidemiology of symptomatic congenital infection |
Early clinical manifestations* |
Late clinical manifestations* |
Diagnosis (prenatal in mother or in amniotic fluid |
Diagnosis (postnatal in newborn) |
|---|---|---|---|---|---|---|---|
|
| |||||||
| Toxoplasma gondii | Intracellular protozoan (foodborne) | Higher risk of transmission in later gestation. More-severe symptoms in earlier gestation 152 | 1–10 per 100,000 live births153 | Intracranial calcifications, hydrocephalus and chorioretinitis | Retardation, seizures and SNHL | Maternal serology Amniotic fluid PCR | T. gondii specific IgG, IgM and IgA and PCR in blood and CSF |
| Asymptomatic in >60% of cases | |||||||
|
| |||||||
| Rubella virus | RNA virus Togaviridae (inhalation) | Highest in first trimester 42 | 0–598 per 100,000 live births154 | Cataract, SNHL, cardiac defects and microphthalmia | Retardation | Maternal serology | Rubella IgM and PCR in blood, nasopharyngeal swab, urine and CSF 153 |
|
| |||||||
| Cytomegalovirus | DNA-herpes virus (bodily fluids and sexual contact) | Transplacental | 0.65 per 1,000 live births 41 | Retinitis and intra-cranial calcifications 80 | Mental retardation, cerebral palsy and seizure disorders 80 | Maternal serology and amniotic fluid PCR | PCR in blood, urine and saliva |
| Asymptomatic in 85% of cases | Specimens must be obtained <21 days of age to reliably diagnose | ||||||
|
| |||||||
| Herpes simplex virus | DNA-herpes virus (bodily fluids) | Intrapartum | 0.3 per 100,000 live births155 | Microcephaly, intra-cranial calcifications, skin andocular findings155 | Maternal serology | HSV1-2 surface cultures and HSV1-2 PCR in blood and CSF | |
|
| |||||||
| Treponema pallidum | Spirochete (sexual contact) | Highest in third trimester156 | 8.7 per 100,000 live births157 | “The great mimic”. Diverse array of symptoms in any major body system 153 | Interstitial keratitis, SNHL and notched teeth158 | Maternal serology (nontreponemal and treponemal) | Non-treponemal test in blood |
CNS Central Nervous System; CSF Cerebrospinal fluid; PCR polymerase chain reaction; SNHL Sensorineural hearing loss.
*
Other than those associated with the infection (for example, rash, thrombocytopenia, anaemia, lymphadenopathy and hepato-splenomegaly)