Viral Conjunctivitis Classification: Taxonomy of Adenovirus and Herpesvirus Causes

Viral Conjunctivitis: Etiologic Classification

Viral conjunctivitis is primarily caused by two virus families. Taxonomy follows the International Committee on Taxonomy of Viruses (ICTV).

Genus: Mastadenovirus (human adenoviruses)
Species associated with conjunctivitis:
- Human mastadenovirus B (types 3, 7, 11, 14, 16, 21, 34, 35, 50, 55)
- Human mastadenovirus D (types 8, 19, 37, 53, 54, 56) — epidemic keratoconjunctivitis (EKC)
- Human mastadenovirus E (type 4) — pharyngoconjunctival fever (PCF)
Clinical syndromes: EKC (severe, contagious, corneal subepithelial infiltrates), PCF (fever, pharyngitis, follicular conjunctivitis), acute nonspecific follicular conjunctivitis.

Subfamily Alphaherpesvirinae
- Genus Simplexvirus: Human alphaherpesvirus 1 (HSV-1), Human alphaherpesvirus 2 (HSV-2)
- Genus Varicellovirus: Human alphaherpesvirus 3 (VZV)
Clinical syndromes:
- HSV: dendritic keratitis, blepharoconjunctivitis, neonatal herpes
- VZV: herpes zoster ophthalmicus (HZO) — dermatomal conjunctivitis/keratitis

Picornaviridae: Enterovirus 70 (acute hemorrhagic conjunctivitis), Coxsackie A24v
Poxviridae: Molluscum contagiosum (lid lesions → follicular conjunctivitis)
Paramyxoviridae: Measles (conjunctivitis prodrome)
Coronaviridae: SARS-CoV-2 (follicular conjunctivitis, rare)

Clinical: follicular vs. papillary, preauricular node, corneal involvement, systemic signs.
PCR (conjunctival swab) — definitive for adenovirus, HSV, VZV, enterovirus.
Rapid antigen test (adenovirus) — moderate sensitivity.
Culture — slow, less sensitive.

Adenovirus: supportive (cold compresses, lubricants); povidone-iodine 0.5% may reduce shedding; topical steroids only if corneal infiltrates (specialist).
HSV/VZV: oral antivirals (aciclovir, valaciclovir) + topical (trifluridine, ganciclovir) for keratitis.
Infection control: strict hygiene (adenovirus survives weeks on surfaces).

Accurate etiology guides therapy, isolation, and prognosis.