Confirmation of the prevention of vertical transmission of Neospora caninum in cattle by the use of embryo transfer

Point-source infections are most likely the cause for Neospora caninum–induced abortion outbreaks in cattle, whereas an increased annual abortion rate may be a consequence of vertical transmission. The aims of the present study were to examine the reproductive effects of neosporosis in a beef herd for 3 years, after a point-source outbreak and to use IgG avidity serology to examine the chronicity of infections and patterns of transmission. During the study, 76–78% of animals were seropositive for N. caninum. The pregnancy rate varied from 88% to 94%, without any reduction in the pregnancy rate of seropositive cows compared with seronegative cows. The annual abortion rate was 2.5–5.5%, and all but 1 abortion occurred in seropositive dams. The efficiency of vertical transmission was estimated to be 85%. Several calves, born to seronegative dams, were seropositive at 6–13 months of age, indicating a 22% mean annual rate of horizontal transmission. The mean avidity in seropositive cows increased from 30 during the initial outbreak to 74 after 3 years. The mode of IgG avidity was 21–40 during the initial abortion outbreak, 41–60 after 1 year, and 61–80 after 2 and 3 years. The results reveal high annual rates of both vertical and horizontal transmission of N. caninum in a herd of beef cows and provide further validation on the ability of the N. caninum IgG avidity ELISA to accurately assess the chronicity of infection.

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Serological Status and Abortion Rate in Progeny Obtained by Natural Service or Embryo Transfer from Neospora caninum-Seropositive Cows

Journal of Veterinary Medicine Series B ◽

10.1046/j.0931-1793.2003.00698.x ◽

2003 ◽

Vol 50 (9) ◽

pp. 458-460 ◽

Cited By ~ 13

Author(s):

C. M. Campero ◽

D. P. Moore ◽

H. Lagomarsino ◽

A. C. Odeon ◽

M. Castro ◽

...

Keyword(s):

Embryo Transfer ◽

Neospora Caninum ◽

Abortion Rate ◽

Serological Status ◽

Natural Service

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Endogenous and exogenous transplacental transmission of Neospora caninum – how the route of transmission impacts on epidemiology and control of disease

Parasitology ◽

10.1017/s0031182009990588 ◽

2009 ◽

Vol 136 (14) ◽

pp. 1895-1900 ◽

Cited By ~ 69

Author(s):

D. J. L. WILLIAMS ◽

C. S. HARTLEY ◽

C. BJÖRKMAN ◽

A. J. TREES

Keyword(s):

Immune Response ◽

Vertical Transmission ◽

Neospora Caninum ◽

Protozoan Parasite ◽

Transplacental Transmission ◽

Highly Efficient ◽

Route Of Transmission ◽

And Control

SUMMARYVertical transmission of the protozoan parasite, Neospora caninum is highly efficient and can take two forms – endogenous transplacental transmission resulting from activation of the quiescent bradyzoite stage during pregnancy or exogenous transplacental transmission resulting from ingestion of oocysts during pregnancy. Calves born carrying infection derived from either endogenous or exogenous transplacental transmission are capable of infecting their offspring when they start to breed. This review considers firstly the frequency with which exogenous and endogenous transmission occur, secondly the role of the immune response in controlling N. caninum infection and thirdly how the parasite persists in an immune-competent host and is re-activated during pregnancy.

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