Bait ingestion by free-ranging raccoons and nontarget species in an oral rabies vaccine field trial in Florida

Oral rabies vaccine-laden baits, with a tetracycline biomarker, were distri buted in Pinellas County (Florida, USA) by helicopter drop and from cars fr om January to April 1997. A total of 130,320 baits was distributed througho ut 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 virginienus), 31 feral cats, and two gray foxes (Urocyon cinereoargenteus) were trapped during February-April 1997. Active surveillance consisted of 1 7 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 trappi ng sites, vegetation communities, and age and sex categories. Since there w as no statistically significant difference in the frequency of tetracycline positive raccoons trapped during active surveillance (59%, 110/187) and pa ssive surveillance (53%, 30/57), the data were pooled, resulting in a tetra cycline positive frequency of 57% (140/244). The range in the positive tetr acycline 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 th e landfills. Juvenile male raccoons (71%, 34/48) were the most commonly mar ked age and sex class and adult females (42%, 21/50) were the least commonl y 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 tetracyclin e-positive.