Investigation of an Outbreak of Epidemic Keratoconjunctivitis (EKC) Due to Adenovirus Type 8 at an Ophthalmology Clinic and a County Jail

BACKGROUND:  Outbreaks of epidemic keratoconjunctivitis (EKC) due to adenovirus have been documented in ambulatory and hospital settings.  EKC is highly contagious, and acute symptoms can include redness, drainage, light sensitivity, and vision loss.  We investigated an EKC outbreak at an ophthalmology clinic in Tennessee, with spread to a county jail.

METHODS:  On August 29, 2012, the Tennessee Department of Health (TDH) was notified of a cluster of EKC cases at a single ophthalmology clinic; the clinic was contacted and infection control measures were reviewed and discussed.  An informational fact sheet describing enhanced infection control measures and a call for EKC cases was sent out on September 7 to all healthcare facilities in the region, including ophthalmology and optometry (eye) clinics. Contact information for eye clinics was obtained via internet searches. A suspect case was defined as any patient displaying EKC symptoms on or after July 25 with any epidemiological link to the ophthalmology clinic.  A subset of the cases was laboratory-confirmed by CDC.  Nosocomial cases were defined as patients with symptom onset within 14 days of a visit to the clinic; community-acquired cases were defined as patients with symptom onset more than 14 days after visit to the clinic or with contact to another case prior to symptom onset. The regional health department was notified of an EKC outbreak among staff at a county jail on October 3.

RESULTS:  Ninety cases of EKC were identified at the ophthalmology clinic.  Three of seven patient samples were positive for adenovirus type 8.  Of the clinic cases, 41 (45.6%) were linked to nosocomial exposures, 43 (47.8%) were community-acquired, and 6 (6.7%) had both nosocomial and community exposures.  The date of visit for all nosocomial cases fell on or before August 31. The median incubation period for nosocomial cases was 11 days.  Seven cases were identified at the local county jail, with symptom onset between September 7 and October 7.  Subsequent investigation identified that the index case (staff member) at the jail visited the ophthalmology clinic on August 30. 

CONCLUSIONS:  Timely notification allowed TDH to assist in interrupting an outbreak of EKC at an ophthalmology clinic and prevented spread among other eye clinics.  A repository containing contact details for outpatient clinics (including eye clinics) would be helpful in performing outreach.  Heightened regional surveillance identified the spread of EKC among county jail staff, allowing for intervention and prevention of further transmission within a closed population.