title: Risk of transplacental transmission of Sarcocystis neurona and Neospora hughesi in California horses.
abstract: The study objective was to assess the risk of transplacental transmission of Sarcocystis neurona and Neospora hughesi in foals from 4 California farms during 3 foaling seasons. Serum of presuckle foals and serum and colostrum of periparturient mares were tested using indirect fluorescent antibody tests for S. neurona and N. hughesi. Serum antibody titers were < or =10 in 366 presuckle foals tested. There was no serologic or histologic evidence of either parasite in aborted fetuses or placentas examined. Positivity for S. neurona and N. hughesi in mares increased with age. Mares < or =9 yr that originated from Kentucky were 3.8 and 1.4 times more likely to be positive for S. neurona and N. hughesi, respectively, than mares from California. The strength of association between positivity to either parasite and state of birth decreased as age increased. Mares positive for S. neurona and N. hughesi were 2.2 and 1.7 times more likely, respectively, to have a previous abortion than negative mares, adjusted for age and state of birth. The annual mortality rate for mares was 4%. The annual incidence rate of equine protozoal myeloencephalitis was 0.2%. In conclusion, there was no detectable risk of transplacental transmission of S. neurona and N. hughesi. Prevalence of antibodies against both parasites in mares increased with age.
authors.affiliation: Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, One Shields Avenue, Davis, California 95616, USA. pdduarte@ucdavis.edu
authors.forename: Paulo C
authors.initials: PC
authors.lastname: Duarte
authors.forename: Patricia A
authors.initials: PA
authors.lastname: Conrad
authors.forename: Bradd C
authors.initials: BC
authors.lastname: Barr
authors.forename: W David
authors.initials: WD
authors.lastname: Wilson
authors.forename: Gregory L
authors.initials: GL
authors.lastname: Ferraro
authors.forename: Andrea E
authors.initials: AE
authors.lastname: Packham
authors.forename: Tim E
authors.initials: TE
authors.lastname: Carpenter
authors.forename: Ian A
authors.initials: IA
authors.lastname: Gardner
mesh_terms: D000034:Abortion, Veterinary / Q000453:epidemiology / Q000469:parasitology; D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood; D002140:California / Q000453:epidemiology; D003048:Coccidiosis / Q000453:epidemiology / Q000635:transmission / Q000662:veterinary*; D015331:Cohort Studies; D003126:Colostrum / Q000276:immunology / Q000469:parasitology; D004679:Encephalomyelitis / Q000453:epidemiology / Q000469:parasitology / Q000662:veterinary; D005260:Female; D019084:Fluorescent Antibody Technique, Indirect / Q000662:veterinary; D006734:Horse Diseases / Q000453:epidemiology / Q000469:parasitology / Q000635:transmission*; D006736:Horses; D015994:Incidence; D018445:Infectious Disease Transmission, Vertical / Q000662:veterinary*; D018688:Neospora / Q000276:immunology*; D011247:Pregnancy; D015597:Pregnancy Complications, Parasitic / Q000453:epidemiology / Q000469:parasitology; D015995:Prevalence; D011446:Prospective Studies; D012307:Risk Factors; D012522:Sarcocystis / Q000276:immunology; D012523:Sarcocystosis / Q000453:epidemiology / Q000635:transmission / Q000662:veterinary*
chemical_list: D000913:Antibodies, Protozoan