Seroprevalence for the tick-borne relapsing fever spirochete Borrelia turicatae among small and medium sized mammals of Texas.

BACKGROUND: In low elevation arid regions throughout the southern United States, Borrelia turicatae is the principal agent of tick-borne relapsing fever. However, endemic foci and the vertebrate hosts involved in the ecology of B. turicatae remain undefined. Experimental infection studies suggest that small and medium sized mammals likely maintain B. turicatae in nature, while the tick vector is a long-lived reservoir. METHODOLOGY/PRINCIPAL FINDINGS: Serum samples from wild caught rodents, raccoons, and wild and domestic canids from 23 counties in Texas were screened for prior exposure to B. turicatae. Serological assays were performed using B. turicatae protein lysates and recombinant Borrelia immunogenic protein A (rBipA), a diagnostic protein that is unique to RF spirochetes and may be a species-specific antigen. CONCLUSIONS/SIGNIFICANCE: Serological responses to B. turicatae were detected from 24 coyotes, one gray fox, two raccoons, and one rodent from six counties in Texas. These studies indicate that wild canids and raccoons were exposed to B. turicatae and are likely involved in the pathogen's ecology. Additionally, more work should focus on evaluating rodent exposure to B. turicatae and the role of these small mammals in the pathogen's maintenance in nature.

Pharmacokinetics of ceftiofur in red deer (Cervus elaphus).

Twelve adult female red deer (Cervus elaphus) were given 250 mg of ceftiofur sodium by intramuscular injection (i.m.) and ballistic implant in a crossover design. Blood samples were taken from an in-dwelling jugular catheter prior to drug administration and at 0.25, 0.5, 1, 2, 4, 8, 12, 24, 36, 48, and 72 h postadministration of the drug. Samples were centrifuged and plasma kept frozen at -70 degrees C until analysis for ceftiofur and active metabolites using an HPLC method. The pharmacokinetics of ceftiofur and metabolites after i.m. dosing and following ballistic implant were quite different. Absorption after i.m. injection was rapid; whereas following ballistic implant there was a lag-time until concentrations were detectable in plasma. The maximum concentration reached in plasma was higher following injection compared with ballistic implant, however the AUC calculated after ballistic implant was almost identical to the mean AUC found after i.m. dosing. The results indicate that i.m. administration of ceftiofur maintains adequate plasma levels for most susceptible bacterial pathogens for at least 12 h; therefore twice daily administration is needed in red deer. Ballistic implants produced plasma concentrations above the MIC for most bacterial pathogens from 4 to 24 h in most animals after administration; however, absorption of the drug was variable and some did not maintain effective concentrations for more than a few hours. Ceftiofur is a useful drug in red deer and twice daily i.m. administration dosing should allow treatment for susceptible bacterial pathogens.