Ehrlichia canis infections have been reported in humans in Venezuela and Costa Rica. In this study, 506 healthy residents and 114 dogs from four municipalities (Cauca, Colombia) were surveyed and blood samples collected. Antibodies to E. canis in human and canine sera were evaluated using the Tandem repeat protein 19 (TRP19) peptide ELISA and indirect immunofluorescence assay (IFA). Ehrlichia canis TRP19 antibodies were detected in only 1/506 human sera, but the single positive sample was negative by IFA. The majority (75/114; 66%) of dogs surveyed had antibodies to the E. canis TRP19 peptide by ELISA, and eight randomly selected sera were further confirmed by E. canis IFA. Genomic DNA samples obtained from 73 E. canis TRP19 ELISA–positive dog blood samples were examined by PCR targeting the 16S rRNA gene. Ehrlichia canis 16S rRNA was amplified in 30 (41%) of the dogs, and 16 amplicons were selected for DNA sequencing, which confirmed that all were E. canis. A second PCR was performed on the 16 confirmed E. canis 16S rRNA PCR–positive samples to determine the TRP36 genotype by amplifying the trp36 gene. TRP36 PCR amplicon sequencing identified nine dogs infected with the U.S. E. canis TRP36 genotype (56%), one dog with the Brazilian genotype (6%), and six dogs with the Costa Rican genotype (38%). Moreover, these molecular genotype signatures were consistent with serologic analysis using TRP36 genotype–specific peptides. Notably, there was no serologic evidence of E. canis infection in humans, suggesting that E. canis infection in dogs in Cauca is not associated with zoonotic human infection.
Address correspondence to Elkin Forero-Becerra, Grupo de Investigación en Medicina Veterinaria y Zootecnia (GIDIMEVETZ), Facultad de Ciencias Agropecuarias, Universidad Pedagógica y Tecnológica de Colombia, Av. Central del Norte No. 39-115, Tunja 150001, Colombia. E-mail: email@example.com
Disclosure: U.S. patents for intellectual property related to the use of TRP19 and TRP36 for immunodiagnosis of E. canis infection have been awarded to J. W. M. An active license agreement to use TRP36 to diagnose E. canis infection exists between the inventors J. W. M. and the Research and Development Foundation and Antech Diagnostics.
Financial support: This work was supported by Colciencias (Project No. 120374455209, Colombia) and the Research Training Program of the Fogarty International Center (United States of America) (grant number 5D43TW010331-04).
Authors’ addresses: Elkin Forero-Becerra, Grupo de Investigación en Medicina Veterinaria y Zootecnia (GIDIMEVETZ), Facultad de Ciencias Agropecuarias, Universidad Pedagógica y Tecnológica de Colombia, Boyacá, Colombia, E-mail: firstname.lastname@example.org. Jignesh Patel, Department of Pathology, University of Texas Medical Branch at Galveston, Galveston, TX, E-mail: email@example.com. Heidy-C Martínez-Diaz, Paola Betancourt-Ruiz, and Marylin Hidalgo, Grupo de Enfermedades Infecciosas, Departamento de Microbiología, Facultad de Ciencias, Pontificia Universidad Javeriana, Bogotá D.C., Colombia, E-mails: firstname.lastname@example.org, email@example.com, and firstname.lastname@example.org. Efraín Benavides and Steven Durán, Grupo de investigación Epidemiología y Salud Pública, Facultad de Ciencias Agropecuarias, Universidad de La Salle, Bogotá, D.C., Colombia, E-mails: email@example.com and firstname.lastname@example.org. Luz Adriana Olaya-M, Programa de Medicina, Facultad de Ciencias de la Salud, Universidad Libre - Cali, Santiago de Cali, Colombia, E-mail: email@example.com. Eliana Bolaños, Secretaría de Salud del Departamento del Cauca, Popayán, Colombia, E-mail: firstname.lastname@example.org. Jere W. McBride, Department of Pathology, Center for Biodefense and Emerging Infectious Diseases, Sealy Institute for Vaccine Sciences, University of Texas Medical Branch, Galveston, TX, E-mail: email@example.com.