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  • Author or Editor: Jeff J. Zimmerman x
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Summary

A total of 2,614 swine from 104 herds located throughout Iowa were tested for antibodies against encephalomyocarditis virus (emcv) by use of the microtitration serum neutralization test. The sample was composed of 587 sows and gilts and 2,027 finishing swine. A statistically significant (P < 0.002) difference was observed between prevalence in sows and gilts (17.2%) and that in finishing swine (12.2%). Breeding swine maintained in total confinement (20.5%) had significantly (P = 0.04) higher prevalence than did breeders maintained in other types of housing (12.1%), whereas prevalence in finishing swine raised in total confinement (6.4%) was significantly (P = 0.02) lower that in finishers not raised in total confinement (13.6%). Association was not detected between prevalence and herd size or between prevalence and season of the year. Adjusting for test specificity and sensitivity, the true prevalence of emcv infection in swine in Iowa was estimated to be 13.8% in breeding stock and 8.5% in finishing swine. On a herd basis, 89.4% (93/104) of the herds had one or more emcv-positive swine.

Free access
in Journal of the American Veterinary Medical Association

Summary

Of swine from 104 herds, 2,616 were tested for antibodies against Toxoplasma gondii, using an elisa. Data were analyzed according to swine type, herd size, facility type, and season. The true prevalence of toxoplasmosis was estimated as 5.4% among finishing swine and 11.4% among sows and gilts. Herds with <100 breeding swine were significantly (P < 0.05) more likely to be infected than were herds with ≥100 breeding swine. The rate of seropositivity in breeding swine was approximately the same in infected herds, regardless of herd size. Herds with finishing swine maintained in total confinement were as likely to become infected as were herds maintained in other types of facilities, but infected herds with finishing swine maintained in confinement appeared to have a lower in-herd prevalence than did herds maintained in other types of facilities (P = 0.09). Seasonal effects were not observed, and prevalence remained relatively constant throughout the year.

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in Journal of the American Veterinary Medical Association

SUMMARY

The survival of pseudorabies virus in an aerosol was studied under different environmental conditions of temperature and relative humidity. Pseudorabies virus decayed logarithmically with mean half-lives of 17.4 (85% relative humidity, 22 C), 18.8 (25% relative humidity, 22 C), 27.3 (85% relative humidity, 4 C), 36.1 (55% relative humidity, 22 C), and 43.6 (55% relative humidity, 4 C) minutes. Virus survival was significantly improved in environments at 55% relative humidity, compared with those at 85% relative humidity (P = 0.017). Rates of survival were improved in environment at 4 C in comparison with those at 22 C. Results suggest that, under the best conditions of this study, the infectivity of pseudorabies virus in an aerosol decreases by 50% in < 1 hour.

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in American Journal of Veterinary Research

Summary

Four boars intranasally inoculated with porcine reproductive and respiratory syndrome (PRRS) virus were monitored for 56 days after exposure for changes in semen characteristics and for the presence of virus in the semen. Clinically, 2 of 4 boars had mild respiratory signs of 1 day's duration after infection. Changes in appetite, behavior, or libido were not detected. All boars seroconverted on the indirect fluorescent antibody and serum virus neutralization tests by day 14 after inoculation. Virus was isolated from serum between days 7 and 14 after inoculation. During the monitoring period, semen volume decreased and pH correspondingly increased; however, this change began 7 to 10 days prior to infection. Differences in sperm morphologic features, concentration, or motility between the preinfection and postinfection samples were not observed. The PRRS virus was detected in semen at the first collection in each of the 4 boars (ie, 3 or 5 days after challenge exposure). Virus was detected in nearly all semen samples collected from the 4 infected boars through days 13, 25, 27, and 43, respectively. Neither gross nor microscopic lesions attributable to PRRS virus were observed in tissues collected at the termination of the experiment (day 56), and virus isolation results from reproductive tissues were negative.

Free access
in Journal of the American Veterinary Medical Association