ARS | Publication request: Depletion Rates of Injected and Ingested Ivermectin from Blood Serum of Penned White-Tailed Deer, Odocoileus Virginianus (Zimmermann) (Artiodactyla: Cervidae)

Submitted to: Journal of Medical Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 17, 2003
Publication Date: January 2, 2004
Citation: Pound, J.M., Miller, J.A., Oehler, D.D. 2004. Depletion Rates of Injected and Ingested Ivermectin from Blood Serum of Penned White-Tailed Deer, Odocoileus Virginianus (Zimmermann) (Artiodactyla: Cervidae). Journal of Medical Entomology.41:65-68

Interpretive Summary: White-tailed deer are the main hosts for ticks that transmit agents that cause Lyme disease, human ehrlichiosis, and other diseases in humans, and are also marginal hosts for cattle fever ticks that may cause fatal diseases in cattle. Field trials have demonstrated that populations of these ticks can be greatly reduced by feeding the deer small amounts of corn coated with ivermectin that prevents the ticks from completing feeding. However, because ivermectin is present in deer that may be hunted and consumed by humans and because ivermectin currently is not permitted to be consumed by humans in the U.S., we need to know how much time it takes for the ivermectin to be depleted from the deer so that the venison will be safe to eat. We treated deer with ivermectin both by injection and ingestion of corn coated with ivermectin, and blood serum samples were taken and analyzed for the concentration of ivermectin remaining in the serum at bi-weekly and weekly intervals after treatment. Concentrations of less than 2 parts per billion were observed within 21 days after treatment in the injection study and 14 days in the ingestion study. Although depletion rates will likely be different in other tissues, data from this study establishes a baseline depletion rate for blood serum in deer, and should aid efforts of the USFDA to establish a realistic withdrawal time for ivermectin from white-tailed deer and allow use of this technology in reducing the risk of Lyme disease, human ehrlichiosis, cattle fever and other debilitating and potentially fatal diseases that are transmitted to humans, livestock, and wildlife as a result of being bitten by ticks.

Technical Abstract: Depletion rates of ivermectin from blood serum of penned doe and buck white-tailed deer that were administered ivermectin both by direct subcutaneous injection and by ingestion of ivermectin-medicated whole kernel corn were determined by bi-weekly and weekly assays of sampled blood. No statistical differences were observed between peak ivermectin serum concentrations of does and bucks in either the injection or ingestion studies, and concentrations decreased to below the minimally detectable concentration of 2 ppb within 21 days after treatment in the injection study and 14 days after termination of treatment in the ingestion study. This study presents conclusive evidence that a relatively high concentrations of ivermectin (14 to 65 ppb) decline rapidly from blood serum of penned white-tailed deer, to the extent that concentrations of <2 ppb are present within 21 days or less after treatment.