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. 2023 Jan 12;10(1):ofac682.
doi: 10.1093/ofid/ofac682. eCollection 2023 Jan.

The Epidemiology and Clinical Features of Non-Keratitis Acanthamoeba Infections in the United States, 1956-2020

Julia C Haston  1   2 , Kevin O'Laughlin  2 , Kelsey Matteson  2   3 , Shantanu Roy  2 , Yvonne Qvarnstrom  4 , Ibne K M Ali  2 , Jennifer R Cope  2
Affiliations

The Epidemiology and Clinical Features of Non-Keratitis Acanthamoeba Infections in the United States, 1956-2020

Julia C Haston et al. Open Forum Infect Dis. .

Abstract

Background: Acanthamoeba is a free-living ameba that can cause severe disease affecting the central nervous system, skin, sinuses, and other organs, particularly in immunocompromised individuals. These rare but severe infections are often fatal, yet incompletely described.

Methods: Cases included were either reported to the Centers for Disease Control and Prevention (CDC) Free-Living Ameba program or published in scientific literature. Characteristics of all patients in the United States with laboratory-confirmed non-keratitis Acanthamoeba infections were described using descriptive statistics, and associations with survival were determined using χ2 and Fisher exact tests.

Results: Of 173 patients identified, 71% were male and the median age was 44 years (range, 0-87 years). Of these, 26 (15%) survived. Most patients (88%) had at least 1 immunocompromising condition, most commonly human immunodeficiency virus (39%), cancer (28%), and solid organ or hematopoietic stem cell transplant (28%). Granulomatous amebic encephalitis (GAE) was the most common disease presentation (71%). Skin (46%), sinuses (29%), lungs (13%), and bone (6%) were also involved. Nearly half of patients (47%) had involvement of >1 organ system. Survival was less frequent among those with GAE (3%, P < .001) compared with cutaneous disease, rhinosinusitis, or multiorgan disease not including GAE. Of 7 who received the currently recommended treatment regimen, 5 (71%) survived.

Conclusions: Non-keratitis Acanthamoeba infections occur primarily in immunocompromised individuals and are usually fatal. Survival may be associated with disease presentation and treatment. Providers who care for at-risk patients should be aware of the various disease manifestations to improve early recognition and treatment.

Keywords: Acanthamoeba; encephalitis; free-living ameba; immunocompromised.

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Conflict of interest statement

Potential conflicts of interest. The authors: No reported conflicts.

Figures

Figure 1.
Figure 1.
Case classification algorithm for assigning disease classification for patients with laboratory-confirmed non-keratitis Acanthamoeba infection. *As determined or suspected by healthcare provider. Abbreviations: CSF, cerebrospinal fluid; GAE, granulomatous amebic encephalitis.
Figure 2.
Figure 2.
Number of non-keratitis Acanthamoeba cases by year, United States, 1956–2020.#Thick arrow denotes the year Acanthamoeba was first diagnosed in a human (1972). Prior cases were diagnosed retrospectively. Thin arrow denotes establishment of the Centers for Disease Control and Prevention (CDC) free-living and intestinal ameba laboratory (1978). Outlined arrow denotes establishment of CDC free-living ameba clinical consultation service (2010). Gray arrow denotes establishment of a national case definition for Acanthamoeba disease (excluding keratitis) (2012).
Figure 3.
Figure 3.
Non-keratitis Acanthamoeba cases by age group and sex, United States, 1956–2020.#Age and sex information was available for 168 patients.
Figure 4.
Figure 4.
Geographic distribution of non-keratitis Acanthamoeba cases, United States, 1956–2020. State of residence was used for geographic classification; state of treatment was used for cases where state of residence was unavailable. State for 9 cases remains unknown.
See this image and copyright information in PMC

References

    1. Visvesvara GS, Moura H, Schuster FL. Pathogenic and opportunistic free-living amoebae: Acanthamoeba spp., Balamuthia mandrillaris, Naegleria fowleri, and Sappinia diploidea. FEMS Immunol Med Microbiol 2007; 50:1–26. - PubMed
    1. Martinez AJ, Visvesvara GS. Free-living, amphizoic and opportunistic amebas. Brain Pathol 1997; 7:583–98. - PMC - PubMed
    1. Stockman LJ, Wright CJ, Visvesvara GS, Fields BS, Beach MJ. Prevalence of Acanthamoeba spp. and other free-living amoebae in household water, Ohio, USA-1990–1992. Parasitol Res 2011; 108:621–7. - PubMed
    1. Jager BV, Stamm WP. Brain abscesses caused by free-living amoeba probably of the genus Hartmannella in a patient with Hodgkin’s disease. Lancet 1972; 2:1343–5. - PubMed
    1. Martinez AJ. Is Acanthamoeba encephalitis an opportunistic infection? Neurology 1980; 30:567–74. - PubMed