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NCID > For Healthcare Professionals > Diseases and Conditions > Conjunctivitis (Viral and Bacterial)

Conjunctivitis (Viral and Bacterial)

Conjunctivitis (Viral and Bacterial)

Causative Agents

Viral: Adenovirus (serotypes 3, 7, 8, 19), enterovirus 70, coxsackievirus A24v and herpes simplex virus.

Bacterial: Staphylococcus aureus (common in adult), Staphylococcus epidermidis, Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, Neisseria gonorrhoeae (in newborns) and Chlamydia trachomatis (in newborns).

Incubation Period

1 - 12 days depending on pathogen

Infectious Period

Throughout the duration of illness; up to 14 days with adenovirus


Highly contagious; direct person-to-person transmission and via contaminated surfaces and articles such as towels. Public swimming pools have not been implicated in the transmission of conjunctivitis in Singapore due to good chlorination. However, the crowded condition facilitates person-to-person transmission.


Epidemics of acute haemorrhagic conjunctivitis caused by picornavirus recurred in a five-year cycle in the 1970s and 1980s. The 1970, 1975 and 1985 epidemics were caused by coxsackievirus A24v and the 1980 epidemic by enterovirus 70.

Coxsackievirus A24 continued to cause outbreaks in 1987, 1992, 2002 and 2005. Most of the viruses isolated during small outbreaks in the inter-epidemic period were adenoviruses.

In 2009, the restructured polyclinics reported 24,084 attendances for conjunctivitis.

General features (viral and bacterial):

  • Acute onset of lacrimation.
  • Foreign body sensation or itchiness.
  • Conjunctival injection.
  • Mild decrease in vision, chemosis, eyelid swelling and crusting may also occur.


  • Recent upper respiratory tract infection or contact with infected person is common.
  • Usually begins in one eye and involves the contralateral eye a few days later.
  • Watery or mucoserous but not purulent discharge.
  • Adenoviral   conjunctivitis    is   frequently   associated   with    preauricular lymphadenopathy and pseudomembranes on the conjunctiva.
  • Picornaviruses such as enterovirus 70 and coxsackievirus A24v typically result in subconjunctival haemorrhages (acute haemorrhagic conjunctivitis).
  • Herpes simplex conjunctivitis may be preceded by history of ocular herpes simplex. There may be herpetic vesicles along eyelid margins or periocular skin. Dendritic corneal ulcers may be seen if the cornea is also involved.


  • Continuous mucopurulent discharge at the lid margins and around the corners of the eye
  • Crusting of eyelids
  • Neisseria species can cause a hyperacute bacterial conjunctivitis, which is severe and sight-threatening and requires urgent ophthalmological consultation

Differential diagnoses

  • Allergic conjunctivitis: history of allergy or atopy is usual as is itching, watery discharge and recurrent episodes.
  • Toxic conjunctivitis: history of application of eye medications causing chemical irritation.
  • Episcleritis: history of dry eye is common. Eye involvement may be sectorial.
  • Scleritis: pain is deep and severe. Sclera may have a bluish hue under natural light.
  • Iritis: circumciliary injection, hazy anterior chamber, pupil miosed, decreased vision.
  • Acute glaucoma: hazy cornea, mid-dilated unreactive pupil, decreased vision, severe eye pain, headache, nausea and vomiting.

  • Virus isolation or PCR specific for picornaviruses or adenoviruses may be performed for outbreak investigation. A rapid test for adenovirus detection is now available.
  • Herpes simplex: sampling should be done by an ophthalmologist, and samples tested by IF, virus isolation or HSV-PCR.
  • Bacterial cultures may be obtained in severe cases. In neonates, cultures may  be needed to exclude Neisseria gonorrhoea. Neonatal conjunctivitis due to Chlamydia trachomatis is diagnosed by sending a posterior conjunctival fornix swab for C. trachomatis IF.

Not required for sporadic cases, but outbreaks should be notified to Ministry of Health for investigation (Form MD 131 or electronically via CD-LENS).

  • Viral conjunctivitis (non-herpetic): supportive treatment with cool compresses several times a day, artificial tears (e.g. normal saline drops, Refresh™, Tears Naturale Free™) 4 - 8 times a day for 1 - 2 weeks, topical antihistamine (e.g. Antazoline) tds if itching is severe. Mild topical steroid (e.g. fluoromethalone qds) may be necessary if there is associated superficial punctate keratitis or pseudomembrane formation. Pseudomembranes should be peeled off using a cotton stick under topical anaesthesia. The use of topical antibiotics is discouraged. Inform the patient of the expected natural course of the  condition i.e. the conjunctivitis will resolve completely in 1 - 4 weeks, even without specific treatment. Remind the patient of the highly contagious nature of the disease.
  • Herpes simplex conjunctivitis: ocular acyclovir 5 times a day for 7 to 10 days should be instituted. Steroids should be avoided because of the risk of enhancing herpetic infection.
  • Bacterial conjunctivitis:
    • Empirical topical antibiotics (e.g. Gutt. chloramphenicol, tobramycin, ciprofloxacin qds or Oc. tetracycline, erythromycin, fusidic acid tds, azithromycin drops 1 drop twice daily for two days, then one drop daily for five days) for 5 to 7 days.
    • Gonococcal conjunctivitis: eye irrigation with normal saline qds, Oc. erythromycin qds or Gutt. ciprofloxacin/penicillin 2 h and IM Ceftriaxone 1 gm in a single dose for adults or 50mg/kg in a single dose for neonates.
    • Chlamydia conjunctivitis: erythromycin 50 mg/kg/day divided q6 for 2 weeks for neonates.
    • Send parents to Kelantan DSC for STD screening if gonoccocal or Chlamydia conjunctivitis diagnosed in neonates.

Education of patient and close contacts is vital to prevent spread. Advice to avoid sharing of face or bath towels, pillows or bedding and to ensure careful hand- washing. Patients should use hygienic measures to dispose of articles soiled by conjunctival discharges.


  1. Khor WB, Aung T, Saw SM et al. An outbreak of Fusarium keratitis associated with contact lens wear in Singapore. JAMA. 2006;295:2867-73.
  2. Yeo DS, Seah SG, Chew JS et al. Molecular identification of coxsackievirus A24 variant, isolated from an outbreak of acute hemorrhagic conjunctivitis in Singapore in 2005. Arch Virol. 2007;152:2005-16.
  3. Ong AE, Dashraath P, Lee VJ. Management of enteroviral conjunctivitis outbreaks in the  Singapore military in 2005. Southeast Asian J Trop Med Public Health. 2008; 39:398-403.
  4. Tarabishy AB, Jeng BH. Bacterial conjunctivitis: a review for internists. Cleve Clin J Med. 2008;75:507-12. Available at Accessed Dec 2010.
  5. Ministry of Health. Surveillance of acute viral conjunctivitis. Epidemiol News Bull 2005; 31:83-6.


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