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Mihai Mititelu, MD, MPH Carolyn Y. Shih, MD, MBA, MPH Ira J. Udell, MD. Acanthamoeba Water Cultures in Patients With and Without Acanthamoeba Keratitis in the New York City Metropolitan Area. The authors have no financial interest in the subject matter of this e-poster. Background.

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Mihai Mititelu, MD, MPHCarolyn Y. Shih, MD, MBA, MPHIra J. Udell, MD

Acanthamoeba Water Cultures in Patients With and Without Acanthamoeba Keratitis in the New York City Metropolitan Area

The authors have no financial interest in the subject matter of this e-poster

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Background

  • Free-living amoebae (FLA) are protozoic organisms that inhabit natural environments (soils, wetlands) and domestic water systems (cooling towers, toilet reservoirs)
  • Acanthamoeba is a genus of FLA that causes Acanthamoeba keratitis (AK) in association with poor contact lens hygiene, contact lens wear while swimming or showering, use of certain contact lens solution, and source water contamination1
  • Prevalence of Acanthamoeba in the water supply ranges from 2.8% in the US2 to 30% in the UK3 to 70% in Mexico4
    • Rates in other countries such as the UK are higher secondary to the use of water storage tanks that promote microbial proliferation5
  • Only one study on the prevalence of Acanthamoeba in the water supply in the US (South Florida)6
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Purpose

  • To evaluate the prevalence of Acanthamoeba in the water supply in Nassau county and Queens county, part of the New York City metropolitan area
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Methods

  • This was a retrospective pilot study
  • Cultures for Acanthamoeba were performed from the shower heads and toilet reservoirs found in the homes of 20 individuals (Table 1) in Nassau county and Queens county:
    • Ten cases with culture-proven AK patients
    • Ten controls without any history of AK from the same geographical area
  • Both shower heads and toilet reservoirs are supplied by the same municipal water sources, but are each exposed to water flows of different temperatures (hot and cold, respectively)
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Results

  • Prevalence of Acanthamoeba in the municipal water supply in the New York city area is 20% for our sample (95% CI:5.7% to 43.7%)
  • Distribution of prevalence of Acanthamoeba in cases (subjects diagnosed with AK) and controls: Table 2
    • Both (2/2) AK cases with positive water samples were CL wearers
    • None (0/2) of the controls with positive water samples were CL wearers
  • Comparison of positive Acanthamoeba culture in shower heads and toilet reservoirs: Table 3
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Results

Table 2

Table 3

  • Exact McNemar’s Text (P < 1.0000)
  • Exact Test (P < 1.0000), OR 1.00 (95% CI: 0.11 to 8.95)
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Conclusions

  • Our small pilot study demonstrates an Acanthamoeba prevalence of 20% in the municipal water supply in Nassau and Queens counties, a figure that – despite its lack of statistical significance - appears higher than previously reported in the US
    • This number was consistent across both the study and control groups
  • There was no statistically significant difference between the Acanthamoeba prevalence rates in water samples obtained from cold sources versus those from sources that mixed hot and cold water
  • It appears that prevalence of Acanthamoeba may be independent of the municipal water supply temperature
  • An association between contact lens wear and AK in individuals exposed to positive water sources may exist
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Limitations and Future Directions

Future Directions

Limitations

  • A study from a larger, random population in another major metropolitan area (such as Chicago, where a break-out of AK was reported in 20067) to get a more statistically significant estimate of the prevalence of Acanthamoeba elsewhere in the US
  • A larger-scale study that investigates the role of the water temperature in the prevalence of Acanthamoeba
  • This was a small pilot study (n=20), therefore some of the results are underpowered and may not be generalizable
  • We used a predetermined number of subjects with and without AK
    • This may have generated an inflated estimate for the prevalence of Acanthamoeba
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References

  • 1. Schamuberg DA, Snow KK, Dana MR. The epidemic of Acanthamoeba keratitis: where do we stand? Cornea. 1998; 17(1):3-10
  • 2,6. Shoff ME, Rogerson A, Kessler K, Schatz S, Seal DV. Prevalence of Acanthamoeba and other naked amoebae in South Florida domestic water.

J Water Health. 2008; 6(1): 100-104

  • 3,5. Kilvington S, Gray T, Dart J, Morlet N, Beeching JR, Frazer D, Matheson M. Acanthamoeba keratitis: the role of domestic tap water contamination in the United Kingdom. IOVS. 2004; 45(1): 165-169
  • 4. Bonilla-Lemus P, Ramirez-Bautista GA, Zamora-Munoz C, del Rocio Ibarra-Montes M, Ramirez-Flores E, Hernandez-Martinez MD. Acanthamoeba spp. In domestic tap water in houses of contact lens wearers in the metropolitan area of Mexico City. Exper Parasitol. 2010; 126:54-58
  • 7. Joslin CE, Tu EY, McMahon TT, Passaro DJ, Stayner LT, Sugar J. Epidemiological characteristics of a Chicago-area Acanthamoeba keratitis outbreak. Am J Ophthalmol. 2006; 142(2):212-217
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Acknowledgements

  • Khurram Chaudhary, MD
  • Lisa Rosen, MS
  • Angela D. Labita, Ophthalmic Photographer
  • North Shore – LIJ Dept. of Ophthalmology staff