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Torch infection and their triads

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I now have excellent source material from multiple authoritative textbooks. Here is the comprehensive answer:

TORCH Infections and Their Triads

TORCH = Toxoplasma | Others (Syphilis, VZV, Parvovirus B19, HIV, Zika) | Rubella | CMV | Herpes simplex
Each infection has a classic triad or constellation of findings in the neonate/infant.

T - Toxoplasmosis (Toxoplasma gondii)

Classic Triad:
  1. Chorioretinitis
  2. Diffuse intracranial (cerebral) calcification - diffuse/scattered pattern
  3. Hydrocephalus
Additional features: seizures, psychomotor retardation, hepatosplenomegaly, jaundice, "blueberry muffin" skin lesions, and pyramidal defects from meningoencephalitis. Cerebral injury around the periaqueductal region obstructs CSF flow, causing hydrocephalus. Calcifications occur in the cerebral cortex and periventricular tissue.
Transmission: Maternal contact with cat feces or ingestion of raw/undercooked meat.
  • Bradley and Daroff's Neurology in Clinical Practice, Andrews' Diseases of the Skin

O - Others

Congenital Syphilis (Treponema pallidum)

Hutchinson's Triad (Late Congenital Syphilis):
  1. Hutchinson teeth - peg-shaped, widely spaced notched incisors
  2. Interstitial keratitis (corneal opacification)
  3. 8th cranial nerve deafness (sensorineural hearing loss)
Early congenital syphilis (before age 2): nasal discharge ("snuffles"), hepatomegaly, jaundice, skeletal abnormalities, generalized lymphadenopathy, mucocutaneous lesions similar to secondary syphilis in adults, periostitis (saber shins).
  • Robbins & Kumar Basic Pathology, Wills Eye Manual, Andrews' Diseases of the Skin

Varicella-Zoster Virus (VZV)

Features: limb hypoplasia, cicatricial skin scarring (in a dermatomal pattern), chorioretinitis, microcephaly, cortical atrophy.

Parvovirus B19

Features: severe fetal anaemia, non-immune hydrops fetalis, stillbirth.

Zika Virus

Features: microcephaly with developmental delay (first trimester exposure).

R - Rubella

Classic Triad of Congenital Rubella Syndrome (CRS):
  1. Sensorineural deafness (most common single defect)
  2. Cardiac malformations - Patent Ductus Arteriosus (PDA), pulmonary artery stenosis
  3. Cataracts (also glaucoma, retinopathy)
Risk is highest in the first 8-10 weeks of gestation (nearly 90% risk). Additional features: low birth weight, "blueberry muffin" rash (dermal extramedullary hematopoiesis), hepatosplenomegaly, jaundice, meningoencephalitis, and developmental delay.
The earlier the infection in pregnancy, the more severe the defects:
  • Before 8 weeks: all three triad defects possible
  • Weeks 8-12: deafness + cardiac defects
  • Weeks 12-16: deafness only
  • Park's Textbook of Preventive & Social Medicine, Jawetz Melnick & Adelberg's Medical Microbiology

C - Cytomegalovirus (CMV)

Most common congenital infection overall and the most common infectious cause of congenital sensorineural hearing loss (SNHL).
CMV does not have a single named triad but its classic constellation is:
  1. Microcephaly with periventricular calcifications (distinguishes from toxoplasma's diffuse calcifications)
  2. Sensorineural hearing loss (progressive)
  3. Chorioretinitis (also optic atrophy, microphthalmos)
Additional features: jaundice, hepatosplenomegaly, intrauterine growth retardation (IUGR), large cerebral ventricles. Owl's eye (nuclear inclusion) appearance on histology.
Only ~5% of infected infants have severe symptoms at birth, but up to 15% of initially asymptomatic infants develop SNHL later.
  • Kanski's Clinical Ophthalmology, K.J. Lee's Essential Otolaryngology, Sherris & Ryan's Medical Microbiology

H - Herpes Simplex Virus (HSV)

Triad of Congenital (In Utero) HSV:
  1. Skin vesicles or scarring
  2. Eye damage (chorioretinitis, keratoconjunctivitis)
  3. CNS damage - microcephaly or hydranencephaly from fetal encephalitis
Note: Congenital (transplacental) HSV is rare. Most neonatal HSV is acquired perinatally (during passage through an infected birth canal) and presents as: (a) skin/eye/mouth disease, (b) CNS encephalitis, or (c) disseminated disease.
  • Bradley and Daroff's Neurology in Clinical Practice

Quick Reference Table

InfectionClassic Triad / Key Features
ToxoplasmosisChorioretinitis + Diffuse intracranial calcifications + Hydrocephalus
Syphilis (Hutchinson's)Hutchinson teeth + Interstitial keratitis + 8th nerve deafness
RubellaCataracts + Cardiac defects (PDA) + Sensorineural deafness
CMVMicrocephaly + Periventricular calcifications + SNHL
HSV (congenital)Skin vesicles/scarring + Eye damage + CNS (microcephaly/hydranencephaly)

Key Distinguishing Points for Exams

  • Most common congenital infection overall: CMV
  • Calcification pattern: Toxoplasma = diffuse/scattered; CMV = periventricular
  • Named triad: Hutchinson's triad belongs to congenital syphilis
  • Blueberry muffin rash: seen in Rubella, CMV, and Toxoplasma (dermal erythropoiesis)
  • Hydrops fetalis: Parvovirus B19
  • Microcephaly with Zika: first trimester maternal infection
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