title: Transstadial and intrastadial experimental transmission of Ehrlichia canis by male Rhipicephalus sanguineus.
abstract: The acquisition and transmission of rickettsial pathogens by different tick developmental stages has important epidemiological implications. The purpose of this study was to determine if male Rhipicephalus sanguineus can experimentally acquire and transmit Ehrlichia canis in the absence of female ticks. Two trials were performed where nymphal and male R. sanguineus were simultaneously acquisition fed on the same infected donor hosts, and transstadially or intrastadially exposed male ticks were fed on separate pathogen-free dogs as a test for transmission. A single-step p30-based PCR assay was used to test canine and tick hosts for E. canis infections before and after tick feeding. E. canis was detected after either intrastadial or transstadial passage in male ticks, the organism remained detectable in both tick groups after transmission feeding, and both tick groups transmitted the rickettsia to susceptible dogs. Infection of dogs via tick feeding resulted in milder clinical signs and lower antibody titers than intravenous inoculation of carrier blood, but further investigation is needed to understand the mechanisms responsible for this observation. These results demonstrate that male R. sanguineus can take multiple feedings, and that they can both acquire and transmit E. canis in the absence of female ticks. This tick development stage could be important in transmission of E. canis, and perhaps related pathogens, between vertebrate hosts under natural and experimental conditions.
authors.affiliation: Department of Veterinary Preventive Medicine, The Ohio State University, 1920 Coffey Road, Columbus, OH 43210, USA.
authors.forename: William G
authors.initials: WG
authors.lastname: Bremer
authors.forename: John J
authors.initials: JJ
authors.lastname: Schaefer
authors.forename: Elizabeth R
authors.initials: ER
authors.lastname: Wagner
authors.forename: S A
authors.initials: SA
authors.lastname: Ewing
authors.forename: Yasuko
authors.initials: Y
authors.lastname: Rikihisa
authors.forename: Glen R
authors.initials: GR
authors.lastname: Needham
authors.forename: Sathaporn
authors.initials: S
authors.lastname: Jittapalapong
authors.forename: Debra L
authors.initials: DL
authors.lastname: Moore
authors.forename: Roger W
authors.initials: RW
authors.lastname: Stich
mesh_terms: D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood; D001179:Arthropod Vectors / Q000382:microbiology*; D001831:Body Temperature; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004283:Dog Diseases / Q000097:blood / Q000382:microbiology* / Q000635:transmission*; D004285:Dogs; D041061:Ehrlichia canis / Q000235:genetics / Q000254:growth & development*; D016873:Ehrlichiosis / Q000097:blood / Q000382:microbiology / Q000635:transmission* / Q000662:veterinary*; D005260:Female; D005455:Fluorescent Antibody Technique / Q000662:veterinary; D006400:Hematocrit / Q000662:veterinary; D026863:Ixodidae / Q000382:microbiology*; D007958:Leukocyte Count / Q000662:veterinary; D008297:Male; D010976:Platelet Count / Q000662:veterinary; D016133:Polymerase Chain Reaction / Q000662:veterinary; D013047:Specific Pathogen-Free Organisms
chemical_list: D000907:Antibodies, Bacterial; D004269:DNA, Bacterial