ORIGINAL PAPER Prevalence of Acanthamoeba spp. and other free-living amoebae in household water, Ohio, USA—1990–1992 Lauren J. Stockman & Carolyn J. Wright & Govinda S. Visvesvara & Barry S. Fields & Michael J. Beach Received: 7 May 2010 / Accepted: 24 September 2010 # Springer-Verlag (outside the USA) 2010 Abstract Knowledge of the prevalence of free-living amoebae (FLA) in US household water can provide a focus for prevention of amoeba-associated illnesses. Household water samples from two Ohio counties, collected and examined for amoebae during 1990–1992, were used to describe the prevalence of Acanthamoeba and other FLA in a household setting. Amoebae were isolated and identified by morphologic features. A total of 2,454 samples from 467 households were examined. Amoebae were found in water samples of 371 (79%) households. Sites most likely to contain amoeba were shower heads (52%) and kitchen sprayers (50%). Species of Hartmannella, Acanthamoeba, or Vahlkampfia were most common. Detection was higher in biofilm swab samples than in water samples. Detection of FLA and Acanthamoeba, at 79% and 51%, respectively, exceed estimates that have been published in previous surveys of household sources. We believe FLA are commonplace inhabitants of household water in this sample as they are in the environment. Introduction Free-living amoebae (FLA), such as those belonging to the genera Acanthamoeba, Echinamoeba, Hartmannella, Nae- gleria, Mastigina, Vahlkampfia, Vannella, and Vexillifera, are small free-living organisms which feed on bacteria, fungi, and other particulate matter and are highly adaptable to their environment. Known to be ubiquitous and found worldwide, FLA can be isolated from air, soil, and water of both natural sources as well as institutional and domestic water systems (Visvesvara and Stehr-Green 1990; Rodriguez-Zaragoza 1994; Thomas et al. 2006). While many FLA are ubiquitous and harmless to humans, several genera are pathogenic. Acanthamoeba species (genotype) Acanthamoeba castellanii (T4), Acanthamoeba culbertsoni (T10), Acanthamoeba hatchetti (T11), Acanthamoeba poly- phaga (T4), Acanthamoeba rhysodes (T4), and Acantha- moeba healyi (T12) have the potential to cause disease such as central nervous system (CNS), skin, and sinus infections, most often in immunocompromised individuals (Visvesvara et al. 2007). In otherwise healthy hosts, Acanthamoeba, Vahlkampfia, and Hartmannella have been associated with corneal infections (Aitken et al. 1996; Lorenzo-Morales et al. 2007; Visvesvara et al. 2007) although causality has not been demonstrated for Vahlkampfia and Hartmannella. Naegleria fowleri has been the cause of fatal CNS infections in children and young adults (CDC 2008; Yoder et al. 2009). Although disease is relatively rare compared with their environmental abundance, these illnesses caused by pathogenic FLA are severe, often challenging to treat, and hence a more complete The findings and conclusions in this report are those of the authors and do not necessarily represent the views of the Centers for Disease Control and Prevention. L. J. Stockman Centers for Disease Control and Prevention, 1600 Clifton Rd NE Mailstop A-34, Atlanta, GA, USA e-mail: bgu8@cdc.gov C. J. Wright : B. S. Fields Centers for Disease Control and Prevention, 1600 Clifton Rd NE Mailstop G-03, Atlanta, GA, USA G. S. Visvesvara Centers for Disease Control and Prevention, 4770 Buford Highway NE Mailstop F-36, Atlanta, GA, USA M. J. Beach (*) Centers for Disease Control and Prevention, 4770 Buford Highway NE Mailstop F-22, Atlanta, GA, USA e-mail: mjb3@cdc.gov Parasitol Res DOI 10.1007/s00436-010-2120-7