Search Results

You are looking at 1 - 8 of 8 items for :

  • "epidemiology" x
  • Refine by Access: All Content x
Clear All

SUMMARY

Phagocytic and nitroblue tetrazolium (nbt) reductive activities of blood neutrophils from 19 Holstein heifers were measured by light microscopic and spectrophotometric methods, respectively. These functional properties of neutrophils correlated well (r = 0.64) and varied significantly (P < 0.05) among animals studied. Variations in phagocytosis and nbt reductive activities attributable to the source of sera were determined in experiments in which cells from the same cows and zymogen particles opsonized with heat-inactivated autologous or homologous sera were used. Variations attributable to the source of cells were determined in experiments in which cells from different cows and particles opsonized with pooled sera from all the cows were used. Most of the variation in phagocytic properties and nbt reductive activities was attributable to the source of cells (ie, each cow). The source of sera contributed slightly to the variation in nbt reductive activities, but not to the phagocytic properties. These results support the concept of functional heterogeneity of neutrophils among cows.

Free access
in American Journal of Veterinary Research

SUMMARY

Mass screening elisa methods were developed for testing cattle serum for antibodies against 14 common livestock diseases simultaneously. The absorbance values were transformed to a %elisa (spectrophotometric antibody end point) by a computer interfaced with a microplate reader. A histogram indicating a cutoff point and a report for the veterinarian also was generated. The computer program produced a print-out of the antibody profile for each animal tested, the antibody concentration against each disease, and a histogram (antibody profile) showing the prevalence of each disease in the herd. Serum samples were obtained from 1,953 cattle, including 880 dairy cattle from 10 herds and 1,073 beef cattle from 20 herds. These samples were obtained from June 1988 through June 1989. The highest antibody prevalence was against bluetongue virus. Of the 1,953 cattle tested, 1,223 (63%) were seropositive for bluetongue virus, including 502 (57%) of the dairy cattle and 721 (67%) beef cattle. Other antibody prevalences, in descending order, were: rotavirus (44%), Pasteurella spp (25%), Leptospira spp and Haemophilus spp (22%), Mycoplasma spp (18%), parainfluenza virus (17%), Campylobacter spp (16%), Anaplasma marginale (15%), bovine leukosis virus (13%), Brucella spp (8%), Mycobacterium paratuberculosis (8%), bovine viral diarrhea virus (3%), and infectious bovine rhinotracheitis virus (3%). Major differences in antibody prevalence between dairy and beef cattle were that only 4% of the dairy cattle were seropositive for A marginale, compared with 25% of the beef cattle, and conversely, 29% of the dairy cattle were seropositive for bovine leukosis virus, compared with 1% of the beef cattle. Further development of the elisa is advocated for mass screening of livestock sera for the application in epidemiologic methods for disease control in food animals.

Free access
in American Journal of Veterinary Research

Summary

A prospective cohort study was undertaken to determine the efficacy of Escherichia coli 0111:B4 (J5) vaccination in dairy calves. Calves on 2 units were vaccinated when they were 2 to 3 days old and 2 weeks later with the J5 antigen or they were left unvaccinated, and were observed during the first 60 days of age for morbidity and mortality. Events recorded were death, the first case of illness, the first sign of a respiratory tract condition, the first sign of diarrhea, and the first treatment. The time to death or to a morbid event was examined as a function of vaccination status, using the Cox model of survival analysis, where serum IgG concentration at 2 to 3 days of age and gender of the calf were included to control confounding. Signs of morbidity in 517 calves were followed, 189 from unit 1 and 328 from unit 2. Vaccination was associated with a 2.15-fold reduction in risk of death on unit 2 (P = 0.042), but with a 2.43-fold increase in risk of death on unit 1 (P = 0.0035). The only association found between vaccination and morbidity was a 1.34-fold reduction in risk of respiratory tract signs for vaccinated calves on unit 2 (P = 0.055). Necropsy results and clinical investigations indicated that calves on unit 1 were poorly nourished and emaciated. Antibodies to J5 2 weeks after vaccination were significantly (P = 0.0002) lower in calves on unit 1 than in calves on unit 2. The findings offered a possible explanation for the adverse vaccination effect in calves on unit 1. Results suggested that vaccination with J5 antigen may be highly beneficial in preventing deaths of reasonably well-managed calves, but may be contraindicated in poorly managed calves.

Free access
in American Journal of Veterinary Research

SUMMARY

Serum IgA, IgG, and IgM concentrations were determined for Beagle sires and dams of 717 matings to assess the relationship of parental immunoglobulins with the morbidity and mortality of their pups. A significant relationship was not found between parental immunoglobulins and pup mortality. Pups born to dams with low serum IgA (P < 0.001) and IgM (P < 0.02) concentrations, however, were found to have an increased incidence of sneezing, coughing, nasal discharge, and conjunctivitis. Thirty-eight percent of pups born to dams with IgA ≤ 40 mg/dl developed these same conditions during the first 18 weeks of life, compared with 32% of pups of dams with IgA of 41 to 65 mg/dl and 27% of pups of dams with IgA > 65 mg/dl. Similarly, 41% of pups born to dams with low IgM (≤ 135 mg/dl) developed abnormal respiratory tract signs, compared with 34% and 30% of pups born to dams with medium (136 to 175 mg/dl) and high (> 175 mg/dl) IgM, respectively. Serum IgA concentrations of the sires were also associated with abnormal respiratory tract signs in pups, but this influence was evident only at 10 to 18 weeks of age.

To determine biologic variability of serum IgA, 60 Beagle dams were selected from 3 serum IgA categories, low (10 to 21 mg/dl), medium (60 to 80 mg/dl), and high (125 to 210 mg/dl). A second serum IgA was determined from a sample taken 2 years later. The intraclass correlation coefficient (rI) indicated considerable biologic variability in all 3 groups: r I = −0.24, r I = 0.09, and rI = 0.46, for low, medium, and high IgA categories, respectively. In contrast, minimal variability was noticed between observers (r I = 0.98) and in the radial immunodiffusion test itself (r I = 0.96).

Free access
in American Journal of Veterinary Research

epidemiology . 2nd ed. New York : CRC Press , 1995 ; 91 – 109 . 12. Dohoo I Martin W Stryhn H . Measures of association . In: Veterinary epidemiologic research . Charlottetown, PEI, Canada : AVC Inc , 2003 ; 121 – 149 . 13. Hall CA

Full access
in American Journal of Veterinary Research

dermatitis and food-induced allergic dermatitis in Switzerland . Vet Dermatol 2008 ; 19 : 150 – 155 . 10.1111/j.1365-3164.2008.00669.x 7. Bjorksten B . The epidemiology of food allergy . Curr Opin Allergy Clin Immunol 2001 ; 1 : 225 – 227 . 8

Full access
in American Journal of Veterinary Research

: 485 – 489 . 10.1136/vr.103.22.485 23. Verhoeff J van Niewstadt AP . BRS virus, PI3 virus and BHV1 infections of young stock on self-contained dairy farms: epidemiology and clinical findings . Vet Rec 1984 ; 114 : 288 – 293 . 10.1136/vr.114

Full access
in American Journal of Veterinary Research

. Taylor JD Fulton RW Lehenbauer TW , et al. The epidemiology of bovine respiratory disease: what is the evidence for predisposing factors? Can Vet J 2010 ; 51 : 1095 – 1102 . 22. Jericho KW Langford EV . Pneumonia in calves

Full access
in American Journal of Veterinary Research