Frequency of horizontal and vertical transmission for Sarcocystis cruzi and Neospora caninum in dairy cattle G. More ´ a,b, *, D. Bacigalupe a , W. Basso a,b , M. Rambeaud a,b , F. Beltrame c , B. Ramirez c , M.C. Venturini a , L. Venturini a a Immunoparasitology and Parasitology Laboratory, Faculty of Veterinary Medicine, National University of La Plata, La Plata, Argentina b Consejo Nacional de Investigaciones Cientı´ficas y Te ´cnicas (CONICET), Argentina c MTsur (MarA ˜ a Teresa Sur), 30 de Agosto, Buenos Aires, Argentina 1. Introduction Sarcocystis cruzi and Neospora caninum infections in cattle are common throughout the world, and cause important economical losses (Dubey, 2003; Dubey et al., 1989). In Argentina prevalence of S. cruzi infection was around 100% (More ´ et al., 2008) and N. caninum seroprevalence, evaluated by indirect fluorescent antibody test (IFAT), was 73% for slaughter animals (More ´ et al., 2008) and 82% for 576 dairy cows from several herds (Venturini, L. unpublished data). In cattle, S. cruzi and N. caninum can be transmitted horizontally by ingestion of sporocysts or oocysts excreted in the feces of dogs and other canids (Basso et al., 2001; Veterinary Parasitology 160 (2009) 51–54 ARTICLE INFO Article history: Received 19 September 2008 Received in revised form 15 October 2008 Accepted 15 October 2008 Keywords: Sarcocystis cruzi Neospora caninum IFAT Vertical transmission Horizontal transmission Dairy cattle ABSTRACT Sarcocystis cruzi and Neospora caninum infections in cattle are common throughout the world, and cause important economical losses. N. caninum can be transmitted horizontally by ingestion of oocysts or vertically from the infected dam to the fetus via the placenta. Vertical transmission for S. cruzi is infrequent and horizontal transmission is considered the most important route of infection. The objectives of this study were to evaluate the frequency of horizontal and vertical transmission for S. cruzi and N. caninum in a dairy cattle herd and to analyze IFAT titers as predictors of vertical transmission. Serum samples (n = 173) were collected from dairy calves at birth prior to colostrum ingestion and from their dams. In addition, 12 calves were also sampled after ingestion of colostrum, 25 female calves were sampled at 7 months, and 81 of the dams were also sampled at breeding. Sera were evaluated for S. cruzi and N. caninum antibodies by IFAT starting at 1:25 dilution. For S. cruzi, vertical transmission frequency was 1.7%, and all female calves evaluated at 7 months and cows were seropositive. Seroprevalence for N. caninum was 80.9% in cows and 30% in precolostrum calves. Vertical transmission frequency was 37.1%. Cows with high antibody titers (400) showed higher vertical transmission frequency (94.8%) than cows with low antibody titers (between 25 and 200) (14.8%). Negative precolostrum calves (7/12) had postcolostrum N. caninum titers 2–8 times higher than their dams. Estimated horizontal transmission frequency was 51 and 47%, based on differences of seroprevalences in calves and dams, and on the seroconversion of 9/19 negative precolostrum female calves when retested at 7 months, respectively. Average N. caninum titers of cows at breeding and calving were 120.6 and 320.9, respectively. Cows with a high titer at breeding had a high titer at calving. Therefore, N. caninum IFAT titers at breeding and calving could potentially be used as predictors of vertical transmission. ß 2008 Elsevier B.V. All rights reserved. * Corresponding author at: Universidad Nacional de La Plata, Facultad de Ciencias Veterinarias, Calle 60 y 118 (1900) La Plata, Argentina. Tel.: +54 221 4249621; fax: +54 221 4257980. E-mail address: gastonmore@fcv.unlp.edu.ar (G. More ´). Contents lists available at ScienceDirect Veterinary Parasitology journal homepage: www.elsevier.com/locate/vetpar 0304-4017/$ – see front matter ß 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.vetpar.2008.10.081