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Updated Outbreak Investigation FAQs

How was the nationwide increase in cases detected?

In 2006, the Illinois Department of Health contacted CDC to report an increase in AK cases in Illinois that were under investigation by the University of Illinois at Chicago. In January 2007, CDC initiated a retrospective survey of 22 ophthalmology centers nationwide to assess whether cases of AK had been increasing in the United States over the past 8 years. In March 2007, data received from 13 of these centers demonstrated an increase in culture-confirmed cases of AK beginning in 2004 with a wide geographic distribution. On March 16, 2007, CDC initiated a multi-state investigation to look for risk factors associated with this increase in AK cases.

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How many people with AK have been identified?

As of June 25, 2007, CDC had received reports from public health authorities and ophthalmologists in 37 states and Puerto Rico identifying 221people with AK, of whom 158 became ill on or after January 1, 2005 and tested positive for Acanthamoeba by cultures taken from corneal specimens. In-depth interviews with 102 people with culture-confirmed AK have been completed.

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How many people with AK are enrolled in this study?

As of June 25, 2007, 102 people with culture-confirmed AK have been enrolled in the study and interviewed. CDC and its partners are now working to obtain and verify data from these people as well as to collect information from a group of people without AK living in the same neighborhoods as AK patients. The information collected from this group of people without AK will be used for comparison purposes in the final data analysis.

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How is information being collected on people with AK?

Standardized telephone interviews of people with AK, their treating ophthalmologists, and their primary eye care providers are being conducted by state and local health officials and staff at CDC. For comparison purposes in the final analysis, similar information is being collected from people without AK living in the patients’ neighborhoods. Laboratory testing at CDC of clinical specimens, contact lenses, bottles of solution, and contact lens cases received from people with AK, including genetic typing of Acanthamoeba, is ongoing.

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Where are these cases occurring?

Nationwide. As of June 25, 2007, people with AK have been identified in 37 states and Puerto Rico.

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Who are the people with AK?

Among the 102 people with culture-confirmed AK who were interviewed and evaluated in a preliminary analysis on June 25, 2007, the median age was 31years (range: 12—76 years); 21 (21%) were aged <18 years. Sixty-four (63%) were female.

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How much eye damage has occurred in people with AK?

Of the 76 patients for whom clinical data were available on June 25, 2007, medical therapy for AK was unsuccessful for 20 (26%). These 20 people were required or expected to undergo corneal transplantation.

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Do most people with AK wear contact lenses?

Yes. Of the 102 people with AK included in a preliminary analysis on June 25, 2007, 79 (77%) wore soft contact lenses, 10 (10%) wore rigid lenses, 1 (1%) wore hybrid lenses, and 12 (12%) reported no contact lens use.

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How many people get AK each year?

AK is a rare disease and information about incidence is limited because AK cases are not required to be reported to CDC. In general, we estimate that only one to two cases of AK per million contact lens users occur each year in the United States, based on an analysis of cases identified during an outbreak of AK during 1985–1987. With an estimated 30 million people in the United States wearing soft contact lenses, this would equate to approximately 30 to 60 cases of AK per year. Information about the previous AK outbreak investigation can be found at our Acanthamoeba Publications Page.

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A square ad showing an infected eyeball with Acanthamoeba. The caption reads, "Delayed diagnosis means poorer outcomes - think Acanthamoeba keratitis."

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