eMedicine Specialties > Ophthalmology > Conjunctiva

Keratoconjunctivitis, Epidemic

Author: Ahmed Bawazeer, MBChB, FRCS(C), Department of Ophthalmology, Division of Uveitis and Cornea, Assistant Professor, King Abdulaziz University, Saudi Arabia
Coauthor(s): William Hodge, MD, Fellowship Director, Assistant Professor, Department of Ophthalmology, University of Ottawa Eye Institute, Canada
Contributor Information and Disclosures

Updated: Jan 7, 2008

Introduction

Background

Epidemic keratoconjunctivitis (EKC) is a type of adenovirus ocular infection. This group of infections also includes pharyngoconjunctival fever and many other adenoviral strains that produce nonspecific follicular conjunctivitis. EKC is highly contagious and has the tendency to occur in epidemics. It has been reported worldwide.

One of the most common causes of acute viral conjunctivitis with unique clinical features is that it produces a sudden onset of acute follicular conjunctivitis with watery discharge, hyperemia, chemosis, and ipsilateral preauricular lymphadenopathy. Both membranes and pseudomembranes can occur in EKC with a distinguishing corneal involvement that ranges from diffuse, fine, superficial keratitis to epithelial defects to subepithelial opacities. Diagnosis is mainly clinical. Treatment is mostly symptomatic (cold compresses and artificial tears). In severe cases, mild topical corticosteroids can be used, especially for the subepithelial opacities.

Pathophysiology

More than 50 serotypes have been isolated, and at least 19 documented serotypes cause EKC. The most commonly associated serotypes include adenovirus 8, 19, and 37, and, less frequently, serotypes 2-5, 7, 9, 10, 11, 14, 16, 21, and 29. Because of low, natural immunity against adenovirus in the general population (eg, adenovirus type 8 antibodies are found in <5% of the general population in the United States), every individual is considered susceptible to infection.

EKC epidemics tend to occur in closed institutions (eg, schools, hospitals, camps, nursing homes, workplaces). Direct contact with eye secretions is the major mode of transmission. Other possible methods of transmission are through air droplets and possibly swimming pools. Adenovirus can be recovered from the eye and throat for as long as 14 days after the onset of clinical symptoms.

The infamous role of the medical profession in spreading the disease is well documented in the literature. Many epidemics have been initiated in ophthalmology outpatient clinics by direct contact with contaminated diagnostic instruments. The following explains the infectious transmission in hospitals and clinics: (1) the virus (adenovirus type 19) remains viable for 5 weeks, (2) the virus is resistant against standard disinfectants, such as 70% isopropyl alcohol and ammonia, and (3) the virus sheds from the eye 3 days before and 14 days after symptom onset.

EKC in East Asia and other parts of the world is endemic and does not appear to be transmitted through medical intervention. Viruses were isolated from more than 50% of cases of viral conjunctivitis; adenovirus constituted 94% of them.

Frequency

United States

The actual prevalence and incidence are unknown, because most cases are seen by general practitioners and optometrists. This infection does not have to be reported to any medical authority.

International

Same as in the United States.

Mortality/Morbidity

EKC is a self-limiting disease. It tends to resolve spontaneously within 1-3 weeks without significant complications.

• In 20-50% of cases, corneal opacities can persist for a few weeks to months (rarely up to 2 y). This phenomenon can significantly decrease visual acuity and cause glare symptoms.
• In rare cases, conjunctival scarring and symblepharon can occur secondary to membranous conjunctivitis.

Sex

No gender predilection exists.

Age

The infection is more common in adults, but all age groups can be affected.

Clinical

History

This eye infection may be preceded by flulike symptoms, including fever, malaise, respiratory symptoms, nausea, vomiting, diarrhea, and myalgia.

• Often, a recent history of an eye examination or exposure within the family or at work is present.
• The incubation period is 2-14 days, and the person may remain infectious for 10-14 days after symptoms develop.
• The ocular symptoms are mainly sudden onset of irritation, soreness, red eye, photophobia, foreign body sensation, and excessive tearing.
• In more severe cases, patients can present with ocular and periorbital pain and decreased visual acuity.
• Symptoms tend to last for 7-21 days. The fellow eye tends to be involved in more than 50% of the cases within 7 days of onset. The signs and symptoms are typically less severe in the fellow eye.

Physical

• Ipsilateral preauricular lymphadenopathy is one of the classic findings.
• Decreased visual acuity is rarely present; it is usually present only if there is corneal involvement.
• Other clinical signs include the following:
  • Swelling and erythema of the lid
  • Conjunctival hyperemia
  • Chemosis
  • Follicular reaction, mainly in the lower palpebral conjunctiva (the earliest and most common sign)
  • Papillary hypertrophy
  • Subconjunctival and petechial hemorrhage
• In severe cases, membranous and pseudomembranous conjunctivitis can be seen in one third of cases, which can lead to conjunctival scarring and symblepharon.
• One of the distinguishing features of EKC is corneal involvement, which is usually mild and transient.
  • Corneal involvement has been well documented 3-4 days after symptom onset in the form of diffuse fine epithelial keratitis that stains with both fluorescein and rose bengal. This keratitis can persist for 2-3 weeks. In rare cases, a frank corneal epithelial defect may occur.
  • One week after the onset, focal epithelial keratitis may develop. This is characterized by central ulceration and irregular borders with gray-white dots. These epithelial changes are related to active viral infection. These lesions persist for 1-2 weeks.
  • About 2 weeks after onset, subepithelial infiltrates can appear beneath the focal epithelial lesions, persisting for weeks to years. They resolve spontaneously, usually without scarring. These infiltrates are immunological in nature.
  • In rare cases, disciform keratitis or anterior uveitis can occur.
  • There is no change in corneal sensation.

Causes

EKC is a type of adenovirus ocular infection. See Pathophysiology.

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