Proposed Field Evaluation of a Rabies Recombinant Vaccine for Raccoons (Procyon Lotor): Site Selection, Target Species Characteristics, and Placebo Baiting Trials

Oral rabies vaccine-laden baits, with a tetracycline biomarker, were distributed in Pinellas County (Florida, USA) by helicopter drop and from cars from January to April 1997. A total of 130,320 baits was distributed throughout the county, yielding an average bait density of 185 baits per km 2 . Bait ingestion was estimated by microscopic detection of tetracycline in tooth and bone samples from 244 raccoons (Procyon lotor), 33 opossums (Didelphis virginianus), 31 feral cats, and two gray foxes (Urocyon cinereoargenteus) that were trapped during FebruaryApril 1997. Active surveillance consisted of 17 trapping sites that were further categorized by six community descriptors. Passive surveillance consisted of animals that were collected as nuisance animals by Pinellas County Animal Services. The proportion of tetracycline positive raccoons was compared between collection techniques, among trapping sites, vegetation communities, and age and sex categories. Since there was no statistically significant difference in the frequency of tetracycline positive raccoons trapped during active surveillance (59%, 110/187) and passive surveillance (53%, 30/57), the data were pooled, resulting in a tetracycline positive frequency of 57% (140/244). The range in the positive tetracycline frequency established for raccoons from the 17 active surveillance sites was 9% (1/11) to 100% (3/3). The tetracycline positive frequency for raccoons ranged from 25% (3/12) at the dumpster sites to 78% (14/18) at the landfills. Juvenile male raccoons (71%, 34/48) were the most commonly marked age and sex class and adult females (42%, 21/50) were the least commonly marked age and sex class. Eighty-five percent (28/33) of the opossums, 3% (1/31) of the feral cats, and 50% (1/2) of the gray foxes were tetracycline positive.

Section: Introductionmentioning

confidence: 99%

Bait Ingestion by Free-Ranging Raccoons and Nontarget Species in an Oral Rabies Vaccine Field Trial in Florida

Olson

Mitchell²,

Werner

2000

“…Tetracyclines are widely used as biomarkers for monitoring vaccine and contraceptive bait consumption in a variety of carnivores and rodents (Linhart and Kennelly, 1967;Crier, 1970;Cowan et al, 1984;Lefebvre et al, 1988;Hanlon et al, 1989;Perry et al, 1989;Bachman et al, 1990;Savarie et al, 1992;Olson et al, 2000;Rosatte and Lawson, 2001). Target species include coyotes (Canis latrans), feral pigs (Sus scrofa), mongoose (Herpestes javanicus), red fox (Vulpes vulpes), gray fox (Urocyon cinereoargenteus), raccoons (Procyon lotor), skunks (Mephitis mephitis, Spilogale putorius), and opossum (Didelphis virginianus).…”

Section: Introductionmentioning

confidence: 99%

“…When administered via intraperitoneal injection, tetracycline can be detected as soon as 12 hr postexposure (Milch et al, 1957). When administered orally, tetracycline can be detected as early as 2 days postconsumption (Hanlon, et al, 1989). Previously published tetracycline biomarker studies have assumed that tetracycline baits were 100% effective in biomarking animals that ingested the baits; the uncorrected frequency of biomarker detection in sampled animals was accepted as the proportion of the exposed populations that consumed the baits.…”

Section: Introductionmentioning

confidence: 99%

Evaluation and Significance of Tetracycline Stability in Rabies Vaccine Baits

Johnston

Primus

Buettgenbach

et al. 2005

Tetracycline is widely used as a biomarker for bait consumption by wildlife; tetracycline is incorporated into bones and teeth and can be detected by fluorescence microscopy several weeks postconsumption. During 2003, the United States Department of Agriculture distributed more than 10 million tetracycline-containing rabies-vaccine baits to control the spread of wildlife vectored rabies to humans, pets, and livestock. To estimate the percentage of target species consuming the baits, raccoons and skunks were collected in baited areas and teeth were analyzed for the presence of the biomarker. Several incidents of low biomarker detection rates prompted an investigation of the stability of the biomarker in the baits. Baits were collected at several points along the manufacturing and distribution chain. Baits were analyzed for free and polymer-bound tetracycline and the less active isomer epitetracycline. Results indicated that a portion of the tetracycline was converted to epitetracycline. Additionally, significant quantities of both compounds were trapped in the polymer, which is homogeneously distributed throughout the bait. The results of this study suggest that approximately 40% of the target quantity of tetracycline was unavailable for absorption. This situation could contribute to low biomarker detection rates and suggests that formulation modification should be considered.

“…No single bait has been effective as a delivery vehicle because each species of carnivore has different food preferences, foraging behaviors, and foraging strategies (Chapman and Feldhamer, 1982). Differences in masticatory behavior of carnivores could cause a bait to be consumed without the oral vaccine being exposed to and absorbed in the buccal mucosa (Rupprecht et al, 1988(Rupprecht et al, , 1989. For example, a rabies vaccine container and bait that effectively immunized red foxes reportedly performed poorly for jackals (Linhart et al, 1997).…”

Section: Introductionmentioning

confidence: 99%

“…Delivery vehicles of oral chemicals to wildlife have included M-44 devices (Baer, 1988), chicken heads (Wandeler et al, 1975), blister pack baits (Bachmann et al, 1990), deep fried corn meal batter (Linhart et al, 1991), meatballs (Johnston and Voight, 1982), tallow-coated sponge cubes (Bachmann et al, 1990), polyethylene capsules with fish-flavored overcoatings (Wlodkowski and Linhart, 1998), dog food-based polymer baits (Farry et al, 1998b), and fish meal-based polymer baits (Hanlon et al, 1989). No single bait has been effective as a delivery vehicle because each species of carnivore has different food preferences, foraging behaviors, and foraging strategies (Chapman and Feldhamer, 1982).…”

Section: Introductionmentioning

confidence: 99%

Bait Delivery for Oral Rabies Vaccine to Gray Foxes

Steelman

Henke

Moore

2000

Rabies is a widespread zoonotic disease that has reached epizootic proportions in gray foxes (Urocyon cinereoargenteus) in central Texas. Because each species of carnivore has different food preferences and foraging strategies, it is essential that the efficacy of a bait delivery program be examined for gray foxes prior to an oral vaccination program being attempted. Field trials were conducted to determine bait preferences of free-ranging gray foxes to selected baits and odor attractants. Baits consisted of polymer cubes made of either dog food meal or fish meal, and a wax-lard cake that was enhanced with marshmallow flavoring. Attractants added to baits exuded sulfurous, fatty, cheesy, or sweet odors and flavors. During 3,589 operable bait station nights, gray fox visitation and bait uptake rates were 9.2% and 8.3%, respectively. Gray foxes exhibited no preference in bait uptake rates between bait and odor attractant combinations. Gray foxes exhibited no difference in cumulative bait uptake rates between onroad and offroad sites; however, the uptake rate by raccoons was significantly greater for baits placed on roads than for baits randomly placed. Raccoons were the major non-target species competing for baits, being attributed with 73% of the total uptake. Visitation and bait uptake rates by raccoons significantly increased after a 7-day lethal removal of raccoons (n ϭ 37) from the study area. Random distribution of baits is recommended; it reduced bait uptake by non-target species without adversely affecting uptake by gray foxes.