Spirochetemia caused by Borrelia turicatae infection in 3 dogs in Texas

Abstract

Spirochetemia was diagnosed in 2 Siberian Huskies and a Rottweiler from the northwestern region of Texas between June 1999 and October 2001. Clinical findings were nonspecific; tick exposure was documented in 2 of the dogs. Hematologic abnormalities included anemia (n=2), neutrophilia (n=2, including 1 with a left shift), lymphopenia (n=3), eosinopenia (n=3), and thrombocytopenia (n=2). One anemic dog had a positive Coombs' test. In 1 dog, Western blot analysis of serum yielded multiple positive bands with B turicatae lysate, indicating the spirochetemia most likely was due to B turicatae infection. In 2 dogs, spirochetes were cultured from the blood and identified using DNA analysis as Borrelia turicatae; 1 of these dogs also was seropositive for Ehrlichia canis and B burgdorferi. In 2 cases, spirochetemia was more prominent in blood smears prepared immediately after sample collection than in smears prepared from EDTA blood. Two dogs recovered with doxycycline treatment; 1 dog declined clinically despite treatment and was euthanized. B turicatae is the agent of tick-borne (endemic) relapsing fever in humans and is distinct from B burgdorferi, the agent of Lyme disease; however, serologic cross-reactivity may occur. B turicatae is transmitted by the soft tick, Ornithodoros turicata, and infection should be considered in dogs with spirochetemia and possible exposure to the tick vector.

Sequence Analysis and Serological Responses against Borrelia turicatae BipA, a Putative Species-Specific Antigen

“…Historically, mapping endemic foci has been associated with capturing ticks at sites where human infection occurred and evaluating the arthropods for spirochete colonization, or by obtaining clinical isolates from sick dogs [2], [3], [17]. Pathogen surveillance based on identifying infected ticks can be difficult because O. turicata are nest-, den-, and cave-dwelling with a 5–60 minute bloodmeal [3], [11], [18], and the ticks are rarely identified on the host.…”

A Novel Surface Antigen of Relapsing Fever Spirochetes Can Discriminate between Relapsing Fever and Lyme Borreliosis

“…Although B. parkeri and B. turicatae have not been isolated from a human, B. turicatae has been implicated in several outbreaks in Texas because of the association of its tick vector with an area where an outbreak occurred (46). B. turicatae has also been isolated from sick dogs (52,58), further supporting the likelihood of infection to humans.…”

Diagnosis and Management of Borrelia turicatae Infection in Febrile Soldier, Texas, USA

“…The vector, the Ornithodoros turicata tick, is endemic to Texas and Florida ( 4 ); but although published cases in Texas have been supported by serology for the TBRF group, exposure location, and tick collections ( 4 , 5 ), to the best of our knowledge, successful identification of B. turicatae in a human has not been reported. Previously, B. turicatae has been isolated only from ticks and canids in several areas of Texas ( 4 – 6 ). …”