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Abstract

Objective

To compare muscle fluid with serum samples for detection of antibodies to Salmonella lipopolysaccharide.

Sample Population

Muscle fluid and serum samples from 2 cattle populations: 1 from the island of Bornholm with no history of salmonellosis (n = 39), and the other from the S dublin-enzootic areas of Jutland (n = 144).

Procedure

Salmonella dublin (O:1,9,12), S typhimu-rium (O:1,4,5,12), and Salmonella O:9-blocking ELISA were used for testing the samples.

Results

In the S dublin ELISA, all serum and muscle fluid samples from cattle on the island of Bornholm had OD450 values well below the cutoff value (0.5). For samples obtained from cattle in the enzootic areas of Jutland, high correlation was found between serum and muscle fluid samples (r s = 0.89, P < 0.001). In addition, 19% (28/144) of the cattle had ELISA-positive muscle fluid and serum samples; 2% (3/144) had positive results for muscle fluid only, whereas 1 animal had positive results for serum only (κ = 0.91, P < 0.0001; sensitivity and specificity of 97%). The same samples had similar significant correlation in the S typhimurium ELISA (r s = 0.88, P < 0.001, κ = 0.7, P < 0.001; sensitivity of 73% and specificity of 98%) and the O:9-blocking ELISA (r s = 0.49, P < 0.001).

Conclusion and Clinical Relevance

Muscle fluid samples taken at slaughter can be used as a practical alternative to serum samples for surveillance of Salmonella infections in cattle. (Am J Vet Res I997;58;334-337)

Free access
in American Journal of Veterinary Research

Abstract

Objective

To follow antibody responses measured by various serologic tests in pigs orally inoculated with low (≤ 10 oocysts) numbers of Toxoplasma gondii oocysts.

Animals

24, 2- to 3-month-old pigs.

Procedure

Pigs (n = 42) were inoculated orally with 10 (14 pigs) or 1 (28 pigs) infective oocysts, and 6 pigs served as uninoculated controls. Blood (serum) samples were obtained at 1- to 3-week intervals until euthanasia. At necropsy, the brain, heart, and tongue of pigs were bioassayed in mice and cats for isolation of T gondii. Modified agglutination test (MAT), using whole, fixed tachyzoites and mercaptoethanol; latex agglutination test (LAT); indirect hemagglutination test (IHAT); Sabin-Feldman dye test (DT); and ELISA were used to evaluate serologic responses to T gondii.

Results

T gondii was isolated from tissues of 13 of 14 pigs each fed 10 oocysts, 17 of 28 pigs each fed 1 oocyst, and 0 of 6 control pigs. 29 of 30 T gondii-infected pigs developed antibodies when measured by MAT, DT, and ELISA; the 1 seronegative-infected pig had been fed 10 oocysts and was euthanatized 69 days after inoculation. LAT detected antibodies in 26 of 30 T gondii-infected pigs. IHAT detected antibodies in 11 T gondii-infected pigs.

Conclusion

MAT, DT, and ELISA were more sensitive serologic assays than LAT and IHAT for detecting antibodies induced by low numbers of T gondii in pigs. (Am J Vet Res 1996;57:1733–1737)

Free access
in American Journal of Veterinary Research

SUMMARY

The sensitivity and specificity of various serologic tests for antibodies to Toxoplasma gondii were compared in 1,000 naturally exposed sows, using isolation of viable T gondii as the definitive test. Serum samples obtained from heart blood of 1,000 sows from Iowa were examined for T gondii antibodies by use of the modified agglutination test (mat), latex agglutination test (lat), indirect hemagglutination test (ihat), and elisa. Toxoplasma gondii was isolated from 170 hearts of 1,000 sows by bioassays in mice and cats. The percentage of samples diagnosed as positive for each of the serologic tests was: mat = 22.2% (titer ≥ 1:20), ihat = 6.4% (titer ≥ 1:64), lat = 10.4% (titer ≥ 1: 64), and elisa = 24.1% (OD > 0.360). The sensitivity and specificity of these tests were calculated respectively to be: 82.9 and 90.29% for mat, 29.4 and 98.3% for ihat, 45.9 and 96.9% for lat, and 72.9 and 85.9% for elisa. The dye test was run at 1:20 dilution on only 893 sera because of bacterial contamination and presence of anticomplement substances. Dye test antibodies were found in 17.8% of the sera, and sensitivity and specificity were 54.4 and 90.8%, respectively. Thus, the mat had the highest sensitivity among all serologic tests used.

Free access
in American Journal of Veterinary Research