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Spatial distribution of seroprevalence for Anaplasma phagocytophilum, Borrelia burgdorferi, Ehrlichia canis, and Dirofilaria immitis in dogs in Washington, Oregon, and California

Authors

  • Danielle Carrade,

    1. Departments of 1Pathology, Microbiology, and Immunology and 2Medicine and Epidemiology, School of Veterinary Medicine, University of California—Davis, Davis, CA, USA; 3IDEXX Laboratories, Westbrook, ME, USA; and 4California State University, Chico, CA, USA
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  • 1 Janet Foley,

    1. Departments of 1Pathology, Microbiology, and Immunology and 2Medicine and Epidemiology, School of Veterinary Medicine, University of California—Davis, Davis, CA, USA; 3IDEXX Laboratories, Westbrook, ME, USA; and 4California State University, Chico, CA, USA
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  • 2 Michael Sullivan,

    1. Departments of 1Pathology, Microbiology, and Immunology and 2Medicine and Epidemiology, School of Veterinary Medicine, University of California—Davis, Davis, CA, USA; 3IDEXX Laboratories, Westbrook, ME, USA; and 4California State University, Chico, CA, USA
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  • 3 Colin W. Foley,

    1. Departments of 1Pathology, Microbiology, and Immunology and 2Medicine and Epidemiology, School of Veterinary Medicine, University of California—Davis, Davis, CA, USA; 3IDEXX Laboratories, Westbrook, ME, USA; and 4California State University, Chico, CA, USA
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  • and 4 Jane E. Sykes 2

    1. Departments of 1Pathology, Microbiology, and Immunology and 2Medicine and Epidemiology, School of Veterinary Medicine, University of California—Davis, Davis, CA, USA; 3IDEXX Laboratories, Westbrook, ME, USA; and 4California State University, Chico, CA, USA
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Janet Foley, Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California—Davis, 1320 Tupper Hall, Davis, CA 95616, USA
E-mail: jefoley@ucdavis.edu

Abstract

Background: In the US little spatially defined information regarding exposure to most vector-borne pathogens in dogs is available for the states of California (CA), Oregon (OR), and Washington (WA).

Objectives: The purpose of the present study was to evaluate the spatial distribution of seroprevalence for 4 vector-borne pathogens, Anaplasma phagocytophilum, Borrelia burgdorferi, Ehrlichia canis, and Dirofilaria immitis, across the 3 western coastal states of the contiguous United States that extend from the northern Mexican to the southern Canadian border.

Methods: A convenience sample, targeting blood from 20 pet dogs per county across CA, OR, and WA, was evaluated using a canine point-of-care ELISA kit. Geographic coordinates of home zip code were displayed using a geographic information system. A total of 2431 dogs from CA, OR, and WA were tested.

Results: The overall seroprevalence was highest for A. phagocytophilum (2.4%), followed by B. burgdorferi (1.2%), and E. canis (0.7%). The prevalence of infection with D. immitis was 0.7%. At the individual dog level, there was a significant association between seropositivity to B. burgdorferi and A. phagocytophilum (odds ratio=18.7, 95% confidence interval=6.8–47.1). For most positive results, prevalence tended to decrease with increasing latitude; thus, the highest rates of seropositivity occurred in CA, followed by OR, and then WA; one exception was seropositivity for B. burgdorferi, which was higher in WA (0.38%) than in OR (0.15%), but considerably lower than in CA (2.00%). In WA, dogs that tested positive for A. phagocytophilum, E. canis, and B. burgdorferi were in the southern Puget Sound area. For D. immitis, none of the dogs in WA was positive.

Conclusions: Seropositivity for vector-borne pathogens is broadly but patchily distributed in dogs in CA, OR, and WA.

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