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 US), 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 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 these.
Frequency:
- In the US: 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.
- Internationally: Same as above.
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 decrease visual acuity significantly 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.
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