Contribution of Leptospira, Neospora caninum and bovine viral diarrhea virus to fetal loss of beef cattle in New Zealand.
The profitability of beef breeding farms in New Zealand depends principally on optimal reproductive performance. The aim of this study was to estimate the impact of four major pathogens, bovine viral diarrhea virus (BVDV), Neospora caninum (N. caninum), Leptospira borgpetersenii serovar Hardjo (Hardjo), and Leptospira interrogans serovar Pomona (Pomona), on rates of fetal loss in commercial beef breeding herds. Farms reporting fetal loss were recruited, and a blood sample from aborting cows (cases) was collected. Controls were normally calving cows from the same farm. At least four controls were selected from each farm contributing cases. Samples were tested using ELISA for detection of antibodies against BVDV and N. caninum, and microscopic agglutination test (MAT) for detection of antibody against Hardjo and Pomona. A selection of titer cut-offs was conducted to evaluate the relationship between fetal loss and seropositivity to each pathogen using conditional logistic regression. The cut-off titer with the strongest association with fetal loss was included in the multivariate model. A significant increased risk of fetal loss was found for animals seropositive to N. caninum (odds ratio (OR)=3.36; 95% confidence interval (95% CI)=1.27-8.89), Hardjo (OR=1.84; 95% CI=1.01-3.33), and Pomona in non-vaccinated cows (OR=14.91, 95% CI=1.73-128.84) at the ELISA titer ≥ 30, and MAT titers of ≥ 1:384 and ≥ 1:768 for a positive sample, respectively. A marginally non-significant increased risk of fetal loss was found for animals exposed to BVDV (OR=2.01; 95% CI=0.99-4.11) at the ELISA titer of ≤ 1. Vaccination did not affect ORs for Hardjo or BVDV and no herd vaccinated against N. caninum. Approximately 14.0% of all fetal loss in the beef breeding cattle population in New Zealand may be attributable to BVDV (3.5%), N. caninum (3.0%), Hardjo (4.7%), and Pomona (3.6%).
EpiCentre, Massey University, Private Bag 11 222, Palmerston North, New Zealand. j.m.sanhueza@massey.ac.nz
J M
JM
Sanhueza
C
C
Heuer
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D
West
D000034:Abortion, Veterinary / Q000453:epidemiology* / Q000382:microbiology / Q000469:parasitology / Q000821:virology; D000372:Agglutination Tests / Q000662:veterinary; D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood; D000913:Antibodies, Protozoan / Q000097:blood; D000914:Antibodies, Viral / Q000097:blood; D001912:Bovine Virus Diarrhea-Mucosal Disease / Q000150:complications / Q000453:epidemiology* / Q000821:virology; D016022:Case-Control Studies; D002417:Cattle; D002418:Cattle Diseases / Q000453:epidemiology* / Q000382:microbiology / Q000469:parasitology / Q000821:virology; D003048:Coccidiosis / Q000150:complications / Q000453:epidemiology / Q000469:parasitology / Q000662:veterinary*; D001908:Diarrhea Viruses, Bovine Viral / Q000302:isolation & purification; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary; D005260:Female; D007919:Leptospira / Q000302:isolation & purification; D007922:Leptospirosis / Q000150:complications / Q000453:epidemiology / Q000382:microbiology / Q000662:veterinary*; D018688:Neospora / Q000302:isolation & purification; D009520:New Zealand / Q000453:epidemiology; D011247:Pregnancy; D015995:Prevalence; D016036:Seroepidemiologic Studies
D000907:Antibodies, Bacterial; D000913:Antibodies, Protozoan; D000914:Antibodies, Viral
BVDV; Beef cattle; Fetal loss; Leptospira; Neospora caninum; PAF