Rickettsia parkeri Infection in Domestic Dogs, Southern Louisiana, USA, 2011

The association between companion animals and tick-borne rickettsial disease has long been recognized and can be essential to the emergence of rickettsioses. We tested whole blood from dogs in temporary shelters by using PCR for rickettsial infections. Of 93 dogs, 12 (13%) were positive for Rickettsia parkeri, an emerging tick-borne rickettsiosis

Borrelia burgdorferi Migration Assays for Evaluation of Chemoattractants in Tick Saliva

Uptake of the Lyme disease spirochete by its tick vector requires not only chemical signals present in the tick’s saliva but a responsive phenotype by the Borrelia burgdorferi living in the mammalian host. This is the principle behind xenodiagnosis, wherein pathogen is detected by vector acquisition. To study migration of B. burgdorferi toward Ixodes scapularis tick saliva, with the goal of identifying chemoattractant molecules, we tested multiple assays and compared migration of host-adapted spirochetes to those cultured in vitro. We tested mammalian host-adapted spirochetes, along with those grown in culture at 34 °C, for their relative attraction to tick saliva or the nutrient N-acetyl-D-glucosamine (D-GlcNAc) and its dimer chitobiose using two different experimental designs. The host-adapted B. burgdorferi showed greater preference for tick saliva over the nutrients, whereas the cultured incubator-grown B. burgdorferi displayed no significant attraction to saliva versus a significant response to the nutrients. Our results not only describe a validated migration assay for studies of the Lyme disease agent, but provide a further understanding of how growth conditions and phenotype of B. burgdorferi are related to vector acquisition

Assessment of Blood Lead, Zinc, and Mercury Concentrations and Cholinesterase Activity in Captive-reared Alligator Snapping Turtles ( Macrochelys temminckii) in Louisiana, USA

The alligator snapping turtle ( Macrochelys temminckii) is a freshwater apex predator that has experienced severe population declines throughout its range due to historical overharvesting and habitat degradation. Because of its long lifespan, high trophic level, and limited home range, it is a suitable sentinel species for monitoring environmental contaminants. In Louisiana, US a pilot program aims to augment free-ranging populations by releasing captive-reared individuals. Baseline values of potential environmental contaminants were determined as part of an overall health assessment to evaluate captive-reared alligator snapping turtles for release. Blood samples from 3-yr-old ( n=23) and 4-yr-old ( n=11) captive-reared alligator snapping turtles were tested for lead (Pb), mercury (Hg), and zinc (Zn) levels by atomic absorption spectrophotometry and cholinesterase (ChE) activity (as a biomarker for organophosphate and carbamate exposure) by the modified Ellman method. Reference intervals were determined for Zn (34 to 295 μg/dL), Hg (0 to 4.8 μg/dL), and ChE (0.17 to 1.65 μmole acetylthiocholine/mL per minute). Elevations of Pb, Zn, or Hg, or decreases in ChE activity levels of this cohort during recapture sampling may indicate point-source intoxications or bioaccumulation, both ultimately attributable to environmental contamination. The released animals may serve as sentinels for biomonitoring of their new habitat for the evaluated toxicants