Download Vaccination of Elk in Wyoming with Reduced Dose Strain 19 Brucella: Controlled Studies and Ballistic Implant Field Trials Online Book PDF

Free Download Vaccination of Elk in Wyoming with Reduced Dose Strain 19 Brucella: Controlled Studies and Ballistic Implant Field Trials Online Book

ByJames D. Herriges (Jr)

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38

“A book is the only place in which you can examine a fragile thought without breaking it.” –Edward Morgan

Synopsis

The presence of brucellosis has been documented in 15 of 23 elk (Cervus elaphus) herds supplementally fed during winter months in western Wyoming. Prevalence among adult females was 16-50% on the five most extensively tested feedgrounds. Controlled studies of the effectiveness in elk of reduced dose strain 19 Brucella abortus vaccine was tested and field trials of a ballistic implant delivery system were conducted. An airgun was used to propel a methylcellulose biobullet containing lyophilized vaccine, which implants in the muscle tissue, dissolved and is absorbed. Five hand-held syringe and biobullet-delivered vaccine trials were conducted with challenge at six to 106 weeks postvaccinaiton. No abortions or positive hemocultures were observed following vaccination and prior to challenge. Elk vaccinated with biobullets containing 5.6-7.6 X 10(9) cfu showed higher antibody titers than elk vaccinated by hand with 1.3-1.5 X 10(9) cfu; low dose (3.7 X 10(7) cfu) biobullet vaccinates showed titers siilar to hand vaccinates. This indicated that the effective dose of biobullet-delivered strain 19 was near the dose loaded into the biobullet. Reduced dose strain 19-induced titers were less persistent in cow and calf elk than those due to standard dose vaccine. Calving success following challenge was 23 (62%) of 37 among vaccinates and was 3 (33%) of 9 among nonvaccinates. At necropsy, 19 (45%) of 42 vaccinates and 9 (69%) of 13 controls were infected. Indices of infection of vaccinate groups were lower than their matched controls. In field trials, elk were marked with an airgun propelled, gelatin-encased paint ball and a biobullet was immediately implanted in the hind quarter. Cow and calf elk were marked and vaccinated from a feed sled or trailer as they fed on hay. Field trials were begun in 1984 and approximately 8,000 doses have been administered to elk on seven feedgrounds. An estimated 3,824 elk were vaccinated during winter 1989, including 88-100% of calves and 71-91% of cows on each feedground.