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Summary

Goats from 28 states were tested for antibodies to caprine arthritis-encephalitis virus. Of 3,790 goats, 1,175 (31%) tested positive, and of 196 herds tested, 143 (73%) had 1 or more seropositive members. This prevalence, based on serum samples from all goats in the participating herds, was lower than most rates reported in other studies. Such studies were based on fewer samples, incomplete sampling of herds, or smaller geographic base. Prevalence was highest in western Pacific and northern plains regions, increased with age to 3 years, was highest among goats on family-owned farms, and was lowest in the Angora breed. Differences in prevalence were not related to gender or size of herd.

Free access
in Journal of the American Veterinary Medical Association

Summary

Ovine progressive pneumonia (opp) is a lentivirus-induced disease of sheep in the United States that is similar, if not identical, to maedi/visna in many other countries. Prevalence estimates of seropositivity to this virus in sheep in the United States have been confined to limited groups or flocks of sheep and have varied from 1 to 90%. In this study of detection of antibodies against opp virus, we found a lower general prevalence of antibodies to opp virus in sheep than was previously reported. Of 16,827 sheep from 29 states in the United States, 26% were seropositive and 48% of 164 flocks that were tested had 1 or more seropositive sheep. Seropositivity to opp virus for sheep within special categories was determined, although nonrandom samples that were available may have biased the results. Within regions of the United States, prevalence was highest in the Rocky Mountain region at 49% and lowest in the northern Atlantic region at 9%. Seropositive sheep were not evenly distributed among flocks, but were clustered in a few flocks of sheep. A high number of flocks had no or few seropositive sheep. Prevalence increased with age from 4% at < 1 year to a plateau of 34% at 4 years. Seropositivity was variable among breeds and was not associated with sex, wool class, or place of origin of ancestors.

Free access
in American Journal of Veterinary Research

SUMMARY

Colostrum-deprived lambs and CF1 mice were vaccinated with water-in-oil emulsion vaccines containing nonviable whole cells (wc) of Corynebacterium pseudotuberculosis with and without muramyl dipeptide (mdp). Efficacy of vaccines was determined from the survival of mice and lesions in lambs after IV injection of 104 colony-forming units of C pseudotuberculosis. In mice, protection was related to the concentration of wc in the vaccine. At 50, 100, or 150 μg of wc, protection was good (78.8%). At 10 or 25 μg of wc, protection was considerably less (54.7%). At high wc concentrations, protection could only be moderately increased to 82.3% with high (50 and 100 μg) concentrations of mdp or increased to 90% protection with low (5 and 10 μg) concentrations of mdp. At low wc concentrations, protection significantly decreased to 32% (P < 0.025) with high concentrations of mdp, but significantly increased to 72.5% (P < 0.025) with low concen-trations of mdp. Therefore, the amount of protection with lower concentrations of wc and mdp was comparable with the amount of protection with higher concentrations of wc without mdp.

In lambs, high prechallenge antibody titers (geometric mean titers from 5.1 to 5.4 by day 35) were observed after vaccination with wc. Protection and vaccination site abscesses in lambs were related to the concentration of wc and mdp. Pulmonary or vaccination site abscesses were not observed in 4 of 4 lambs vaccinated with 1 mg of wc + 50 μg of mdp.

Free access
in American Journal of Veterinary Research