Estimation of vertical and horizontal transmission parameters of Neospora caninum infections in dairy cattle.
Transmission parameters of Neospora caninum infections in dairy cattle were determined in six herds with a history of Neospora-associated abortions, using an antibody-detection ELISA to detect evidence of infection. A total of 124 seropositive dams and their calves were tested at calving to estimate vertical transmission, and 154 seronegative heifers were monitored prospectively from birth for evidence of post-natal infection. The probability of vertical transmission was very high; 95.2% (95% confidence interval: 89.8%, 98.2%) of the seropositive dams produced calves that were seropositive prior to consumption of colostrum. In the prospective study, three heifers seroconverted, by 1, 8 and 16 months of age, and the overall incidence rate of seroconversion was 1.9 per 100 heifer-years at risk, ranging from 0 to 4.1 per 100 heifer-years at risk within herds. If heifers with inconclusive ELISA results were included in the analysis, the incidence rate of seroconversion was 3.8 per 100 heifer-years at risk, ranging from 0 to 8.3 per 100 heifer-years at risk within herds. This study showed that vertical transmission was the major route involved in the spread of N. caninum in these herds, and that there was only a low detectable level of horizontal transmission. However, further studies are needed to provide parasitological evidence of infection in those heifers that seroconverted.
Davison
H C
HC
Veterinary Parasitology, Liverpool School of Tropical Medicine/Faculty of Veterinary Science, University of Liverpool, UK.
Otter
A
A
Trees
A J
AJ
D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood; D002417:Cattle; D002418:Cattle Diseases / Q000635:transmission*; D003048:Coccidiosis / Q000635:transmission / Q000662:veterinary*; D003612:Dairying; D018562:Disease Transmission, Infectious / Q000662:veterinary*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D018445:Infectious Disease Transmission, Vertical / Q000662:veterinary*; D018688:Neospora / Q000276:immunology; D011247:Pregnancy; D015597:Pregnancy Complications, Parasitic / Q000662:veterinary
D000913:Antibodies, Protozoan