Is conjunctivitis contagious?

Is Conjunctivitis Contagious?

Yes, conjunctivitis is highly contagious when caused by viral or bacterial pathogens, and certain types like chlamydial conjunctivitis spread easily through hands, fomites, flies, and other contact. 1

Contagious Forms of Conjunctivitis

Viral Conjunctivitis

• Highly contagious and accounts for approximately 80% of all acute infectious conjunctivitis cases 2, 3
• Spreads through exposure to infected individuals, particularly in school settings, and via contaminated droplets 1
• Contagious period lasts 10-14 days from onset of symptoms 1
• Adenoviral conjunctivitis (epidemic keratoconjunctivitis) is especially transmissible and can cause outbreaks 3

Bacterial Conjunctivitis

• Moderately contagious, particularly in children 2, 4
• Transmission occurs through contact with infected individuals, eye-hand contact, and contaminated surfaces 1
• Gonococcal conjunctivitis spreads via oculogenital contact and requires consideration of sexual abuse in children 1

Chlamydial Conjunctivitis

• Highly communicable via hands, fomites, flies, and other contact 1
• Sexually transmitted in adults (serotypes D-K) 1
• Trachoma (serotypes A, B, C) spreads by direct or indirect contact with eye, nose, or throat secretions 1

Herpes Simplex Virus (HSV)

• Primary HSV infection spreads through exposure to infected individuals 1
• Reactivation can be triggered by stress, other illnesses, UV exposure, surgery, or trauma 1

Non-Contagious Forms

Allergic Conjunctivitis

• Not contagious - affects 6-40% of the general population but does not spread person-to-person 1
• Itching is the most consistent sign 2, 5

Other Non-Infectious Causes

• Mechanical/irritative/toxic conjunctivitis, immune-mediated conditions, and neoplastic causes are not transmissible 1

Critical Prevention Measures

Breaking the chain of transmission requires strict hygiene protocols: 1

• Hand washing is the single most important preventive measure 1, 5
• Infected individuals should use separate towels and pillows 1
• Avoid close contact with others during the contagious period 1
• Tonometers must be disinfected with 1:10 dilute bleach solution (sodium hypochlorite) - 70% isopropyl alcohol is no longer recommended 1
• Single-use disposable tonometer tips circumvent sterilization issues 1

Return to Work/School Considerations

• Depends on the type and severity of conjunctivitis, patient age, and occupation 1
• Viral conjunctivitis patients should avoid close contact for 10-14 days 1
• Bacterial conjunctivitis patients can return earlier with antibiotic treatment 2

Common Pitfall

A critical error is inadequate disinfection of medical equipment, particularly tonometers, which can transmit epidemic adenoviral conjunctivitis between patients 1. Healthcare providers must use proper disinfection protocols (1:10 bleach solution) rather than ineffective methods like alcohol wipes 1.