The efficiency of vertical transmission of Neospora caninum in dairy cattle analysed by serological techniques

The association of Neospora caninum infections with cattle families was exa mined in a dairy cattle herd with sporadic abortions using three different serological tests. Cattle seropositive for N. caninum clustered in six fami lies, three of which encountered abortions. In absence of age related diffe rences in the N. caninum seroprevalence, the family association of N. canin um infection indicated that congenital infection represented the predominan t route of transmission in this herd. Fourteen (93%) out of 15 descendants of 10 seropositive cows were seropositive themselves. Only one female calf of a seropositive cow remained seronegative and gave birth to a calf which was tested seronegative again. Only one seronegative cow that had two seron egative descendants also gave birth to one seropositive calf. This was the only indication for potential postnatal transmission that occurred in the h erd. The results of this study suggest that the N, caninum-infection can be maintained over several generations at a nearly constant prevalence level, apparently without a need for dispersion by an definitive host. (C) 1998 E lsevier Science B.V. All rights reserved.