Enzootic toxoplasmosis in sheep in north-central United States.
Of 1,564 serum samples from adult ewes from 33 farms in Iowa, Minnesota, South Dakota, Kansas, and Nebraska where toxoplasmosis-induced ovine abortions had been diagnosed, 65.5% were found positive for Toxoplasma gondii antibodies using the modified agglutination test. Toxoplasma gondii antibody titers of ewes were: less than 64 (34.5%), 64 (14.9%), 256 (22.0%), 1,024 (14.5%), and greater than 4,096 (13.8%). Thus, 28.3% of sheep had high titers (greater than 1,024) indicating recently acquired T. gondii infection. On certain farms, up to 95% of ewes were seropositive. Prevalence of T. gondii antibodies increased with age of the ewe. Of 665 ewes, 53.6% of 1-yr-old ewes were seropositive (titers greater than 64) versus 75% of 5-yr-old ewes. Results indicate that T. gondii infection in sheep in the United States is widespread.
Dubey
J P
JP
Zoonotic Diseases Laboratory, U.S. Department of Agriculture, Beltsville, Maryland 20705.
Kirkbride
C A
CA
D000818:Animals; D000913:Antibodies, Protozoan / Q000032:analysis*; D005260:Female; D015146:Midwestern United States / Q000453:epidemiology; D012756:Sheep / Q000276:immunology*; D012757:Sheep Diseases / Q000453:epidemiology*; D014122:Toxoplasma / Q000276:immunology*; D014124:Toxoplasmosis, Animal / Q000453:epidemiology*
D000913:Antibodies, Protozoan