Dynamics of <i>Neospora caninum</i>-Associated Abortions in a Dairy Sheep Flock and Results of a Test-and-Cull Control Programme
Roberto Sánchez-Sánchez,
Ángela Vázquez-Calvo,
Mercedes Fernández-Escobar,
Javier Regidor-Cerrillo,
Julio Benavides,
Jorge Gutiérrez,
Daniel Gutiérrez-Expósito,
Francisco José Crespo-Ramos,
Luis Miguel Ortega-Mora,
Gema Álvarez-García
Affiliations
Roberto Sánchez-Sánchez
SALUVET Group, Animal Health Department, Faculty of Veterinary Sciences, Complutense University of Madrid, Ciudad Universitaria s/n, 28040 Madrid, Spain
Ángela Vázquez-Calvo
SALUVET-Innova, S.L., Complutense University of Madrid, 28040 Madrid, Spain
Mercedes Fernández-Escobar
SALUVET Group, Animal Health Department, Faculty of Veterinary Sciences, Complutense University of Madrid, Ciudad Universitaria s/n, 28040 Madrid, Spain
Javier Regidor-Cerrillo
SALUVET-Innova, S.L., Complutense University of Madrid, 28040 Madrid, Spain
Julio Benavides
Instituto de Ganadería de Montaña (CSIC-Universidad de León), 24346 León, Spain
Jorge Gutiérrez
MSD Animal Health, Polígono Industrial El Montalvo, C/Zeppelin, 6—Parcela 38, Carbajosa de La Sagrada, 37008 Salamanca, Spain
Daniel Gutiérrez-Expósito
Instituto de Ganadería de Montaña (CSIC-Universidad de León), 24346 León, Spain
Francisco José Crespo-Ramos
Consorcio de Promoción del Ovino, Camino Canillas s/n, Villalpando, 49630 Zamora, Spain
Luis Miguel Ortega-Mora
SALUVET Group, Animal Health Department, Faculty of Veterinary Sciences, Complutense University of Madrid, Ciudad Universitaria s/n, 28040 Madrid, Spain
Gema Álvarez-García
SALUVET Group, Animal Health Department, Faculty of Veterinary Sciences, Complutense University of Madrid, Ciudad Universitaria s/n, 28040 Madrid, Spain
Neospora caninum is an apicomplexan parasite that can cause abortions and perinatal mortality in sheep. Although ovine neosporosis has been described worldwide, there is a lack of information about the relationship between N. caninum serostatus and the reproductive performance. In this study, we described the infection dynamics in a dairy sheep flock with an abortion rate up to 25% and a N. caninum seroprevalence of 32%. Abortions were recorded in 36% and 9% of seropositive and seronegative sheep, respectively. Seropositive sheep were more likely to abort twice (OR = 4.44) or three or more times (OR = 10.13) than seronegative sheep. Endogenous transplacental transmission was the main route of transmission since 86% of seropositive sheep had seropositive offspring. Within dams that had any abortion, seropositive sheep were more likely than seronegative ones to have female descendants that aborted (OR = 8.12). The slight increase in seropositivity with the age, the low percentage of animals with postnatal seroconversion or with low avidity antibodies, and the seropositivity of one flock dog, indicated that horizontal transmission might have some relevance in this flock. A control programme based on selective culling of seropositive sheep and replacement with seronegative animals was effective in reducing the abortion rate to 7.2%.
