Incidence of Acanthamoeba Keratitis in Switzerland

Frank Blaser¹, Felix Grimm², Philipp B Baenninger³, Zisis Gatzioufas⁴, Michael A Thiel⁵, Moreno Menghini⁶, Beatrice E Frueh⁷, Konrad Muehlethaler⁸, Marco Alder⁹, Kattayoon Hashemi¹⁰, René Brouillet¹¹, Horace Massa¹², Manolito L Finger¹³, Christoph Tappeiner^{14

15

16}, Anthia Papazoglou^{1

17}, Florentina Joyce Freiberg¹⁸, Gilbert Greub¹⁹, Daniel Barthelmes¹, Sandrine A Zweifel¹, Sadiq Said^{1

20}

Affiliations

¹ Department of Ophthalmology, University Hospital Zurich, University of Zurich, 8091 Zurich, Switzerland.
² Institute of Parasitology, University of Zurich, 8006 Zurich, Switzerland.
³ Department of Ophthalmology, Cantonal Hospital Winterthur, 8400 Winterthur, Switzerland.
⁴ Department of Ophthalmology, University Hospital Basel, 4056 Basel, Switzerland.
⁵ Department of Ophthalmology, Cantonal Hospital Lucerne, 6000 Lucerne, Switzerland.
⁶ Department of Ophthalmology, Institute of Clinical Neurosciences of Southern Switzerland (INSI), Ente Ospedaliero Cantonale (EOC), 6900 Lugano, Switzerland.
⁷ Department of Ophthalmology, Bern University Hospital, Inselspital, University of Bern, 3010 Bern, Switzerland.
⁸ Institute for Infectious Diseases, University of Bern, 3012 Bern, Switzerland.
⁹ Department of Ophthalmology, Cantonal Hospital St. Gallen, 9007 St. Gallen, Switzerland.
¹⁰ Department of Ophthalmology, University of Lausanne, Jules-Gonin Eye Hospital, Fondation Asile des Aveugles, 1004 Lausanne, Switzerland.
¹¹ Institute of Microbiology, University of Lausanne, 1015 Lausanne, Switzerland.
¹² Department of Ophthalmology, University Hospital Geneva, University of Geneva, 1205 Geneva, Switzerland.
¹³ Department of Ophthalmology, Cantonal Hospital Fribourg, 1752 Fribourg, Switzerland.
¹⁴ Department of Ophthalmology, Pallas Klinik, 4600 Olten, Switzerland.
¹⁵ Department of Ophthalmology, University Hospital Essen, University Duisburg-Essen, 45147 Essen, Germany.
¹⁶ Medical Faculty, University of Bern, 3012 Bern, Switzerland.
¹⁷ Department of Ophthalmology, Cantonal Hospital Aarau, 5000 Aarau, Switzerland.
¹⁸ Department of Ophthalmology, City Hospital Triemli, 8055 Zurich, Switzerland.
¹⁹ Service of Microbiology, University Hospital of Lausanne, 1005 Lausanne, Switzerland.
²⁰ Augenklinik Wettingen, 5430 Wettingen, Switzerland.

PMID: 41011364
PMCID: PMC12471702
DOI: 10.3390/microorganisms13092032

Incidence of Acanthamoeba Keratitis in Switzerland

Frank Blaser et al. Microorganisms. 2025.

. 2025 Aug 30;13(9):2032.

doi: 10.3390/microorganisms13092032.

Authors

Affiliations

¹ Department of Ophthalmology, University Hospital Zurich, University of Zurich, 8091 Zurich, Switzerland.
² Institute of Parasitology, University of Zurich, 8006 Zurich, Switzerland.
³ Department of Ophthalmology, Cantonal Hospital Winterthur, 8400 Winterthur, Switzerland.
⁴ Department of Ophthalmology, University Hospital Basel, 4056 Basel, Switzerland.
⁵ Department of Ophthalmology, Cantonal Hospital Lucerne, 6000 Lucerne, Switzerland.
⁶ Department of Ophthalmology, Institute of Clinical Neurosciences of Southern Switzerland (INSI), Ente Ospedaliero Cantonale (EOC), 6900 Lugano, Switzerland.
⁷ Department of Ophthalmology, Bern University Hospital, Inselspital, University of Bern, 3010 Bern, Switzerland.
⁸ Institute for Infectious Diseases, University of Bern, 3012 Bern, Switzerland.
⁹ Department of Ophthalmology, Cantonal Hospital St. Gallen, 9007 St. Gallen, Switzerland.
¹⁰ Department of Ophthalmology, University of Lausanne, Jules-Gonin Eye Hospital, Fondation Asile des Aveugles, 1004 Lausanne, Switzerland.
¹¹ Institute of Microbiology, University of Lausanne, 1015 Lausanne, Switzerland.
¹² Department of Ophthalmology, University Hospital Geneva, University of Geneva, 1205 Geneva, Switzerland.
¹³ Department of Ophthalmology, Cantonal Hospital Fribourg, 1752 Fribourg, Switzerland.
¹⁴ Department of Ophthalmology, Pallas Klinik, 4600 Olten, Switzerland.
¹⁵ Department of Ophthalmology, University Hospital Essen, University Duisburg-Essen, 45147 Essen, Germany.
¹⁶ Medical Faculty, University of Bern, 3012 Bern, Switzerland.
¹⁷ Department of Ophthalmology, Cantonal Hospital Aarau, 5000 Aarau, Switzerland.
¹⁸ Department of Ophthalmology, City Hospital Triemli, 8055 Zurich, Switzerland.
¹⁹ Service of Microbiology, University Hospital of Lausanne, 1005 Lausanne, Switzerland.
²⁰ Augenklinik Wettingen, 5430 Wettingen, Switzerland.

PMID: 41011364
PMCID: PMC12471702
DOI: 10.3390/microorganisms13092032

Abstract

Despite rising global reports of Acanthamoeba keratitis (AK), the incidence of AK in Switzerland remains unknown. This investigator-initiated, retrospective, multicenter study assessed the nationwide incidence of PCR- and/or culture-positive Acanthamoeba results from January 2010 to December 2023. Data were collected from all tertiary care and large ophthalmological facilities in Switzerland, fully anonymized, and aggregated by month and year. We considered all corneal scraping results, whereby the detection method was specific to local standards. We identified 271 PCR- or culture-positive Acanthamoeba cases over 14 years. Applying the population data from the Federal Statistical Office in Switzerland, this corresponds to a mean incidence of 2.29 cases per million people annually. Infections were most common in summer (87 cases, 32.1%), followed by autumn (74 cases, 27.3%), spring (60 cases, 22.1%), and winter (50 cases, 18.5%). We found no significant change in incidence across the investigated period, p = 0.47. This nationwide study reveals a low but stable incidence of AK in Switzerland, in line with other industrialized countries but well below levels reported in tropical or densely populated regions such as India or Egypt. Seasonal variation supports the influence of environmental exposure and underscores the importance of preventive measures during warmer months.

Keywords: Switzerland; acanthamoeba keratitis; epidemiology; incidence; infectious keratitis.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

**Figure 1**
Illustration of the cumulative number of polymerase chain reaction or culture-positive Acanthamoeba cases reported per center on a map of Switzerland. The dashed line represents the linguistic relative separation between the country’s German, French, and Italian parts. The size of the red circle displays the number of positive Acanthamoeba cases in the final analyses across the studied time period from January 2010 to December 2023. EOS = Ticino Cantonal Hospital; HFR = Cantonal Hospital Fribourg; HUG = University Hospital Geneva; Insel = University Hospital Bern; CHUV = Lausanne University Hospital and Jules-Gonin Eye Hospital; KSA = Cantonal Hospital Aarau; KSSG = Cantonal Hospital St. Gallen; KSW = Cantonal Hospital Winterthur; LUKS = Cantonal Hospital Lucerne; Pallas = Pallas Kliniken; Triemli = City Hospital Triemli; USB = University Hospital Basel; USZ = University Hospital Zurich.

**Figure 2**
Annual incidence of positive Acanthamoeba results. The incidence rates are displayed as cases per million people. The blue line displays the regression trend line examined using a linear regression model. Although the data visually imply an increase over the years, linear regression analysis revealed no statistically significant temporal trend (estimate 0.039, standard error 0.053, t = 0.74, p = 0.47).

**Figure 3**
Seasonal case counts across the entire study period. The incidence rates are displayed as cases per million people. There was a significant difference in positive Acanthamoeba results between summer (June, July, August) and winter (December, January, February), p = 0.01. The other comparisons were not statistically significant.

See this image and copyright information in PMC

References

1. Berrilli F., Montalbano Di Filippo M., Guadano-Procesi I., Ciavurro M., Di Cave D. Acanthamoeba Sequence Types and Allelic Variations in Isolates from Clinical and Different Environmental Sources in Italy. Microorganisms. 2024;12:544. doi: 10.3390/microorganisms12030544. - DOI - PMC - PubMed
1. Lorenzo-Morales J., Khan N.A., Walochnik J. An update on Acanthamoeba keratitis: Diagnosis, pathogenesis and treatment. Parasite. 2015;22:10. doi: 10.1051/parasite/2015010. - DOI - PMC - PubMed
1. Maycock N.J., Jayaswal R. Update on Acanthamoeba Keratitis: Diagnosis, Treatment, and Outcomes. Cornea. 2016;35:713–720. doi: 10.1097/ICO.0000000000000804. - DOI - PubMed
1. Schuster F.L., Visvesvara G.S. Free-living amoebae as opportunistic and non-opportunistic pathogens of humans and animals. Int. J. Parasitol. 2004;34:1001–1027. doi: 10.1016/j.ijpara.2004.06.004. - DOI - PubMed
1. Naginton J., Watson P.G., Playfair T.J., McGill J., Jones B.R., Steele A.D. Amoebic infection of the eye. Lancet. 1974;2:1537–1540. doi: 10.1016/S0140-6736(74)90285-2. - DOI - PubMed

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Incidence of Acanthamoeba Keratitis in Switzerland

Affiliations

Incidence of Acanthamoeba Keratitis in Switzerland

Authors

Affiliations

Abstract

Conflict of interest statement

Figures

References

LinkOut - more resources

Full Text Sources