Von der Bedeutung der bovinen Neosporose beim Abortgeschehen in der Schweiz

Abstract

The protozoan parasite Neospora caninum is one of the most important infectious abortion causes in cattle worldwide. In a Swiss case-control-study we investigated 113 abortion problem farms and 113 control farms. It was possible to detect N. caninum in 21% of 242 investigated aborted fetuses by PCR upon brain samples. Eighty-four % of mothers aborting N. caninum positive fetuses were serologically positive for this parasite. The seroprevalence for N. caninum of all aborting mothers was 44%. Within a period of 3 to 12 months 4,505 cattle from the participating farms were investigated serologically at two different time points. Strong fluctuations of the specific antibody concentration could be observed, resulting in a conversion to seronegativity in the second blood sample in 39% of formerly seropositive animals. Eighteen months after the end of the study, 42 case- and 42 controlfarms were questioned about their present abortion-status. Analysis of the questionnaire revealed that 80% of the former abortion problem farms observed an improvement of the situation. However, in 43% of those farms no preventive measures had been taken and no significant differences in hygiene, forage and animal turnover could be observed between case- and control-farms. Additionally, no significant differences were detected concerning risk factors such as the presence of farm dogs and the disposal procedure for placental and fetal material.

Neosporacaninum immunoblotting improves serodiagnosisof bovine neosporosis

“…In cattle, N. caninum antibodies were shown to fluctuate during pregnancy and also in between, and they may, at least with some assays, even drop below detection limits (Björkman and Uggla 1999). Similar observations were done in Switzerland (Sager et al 2001;Fischer et al 2003) and a recent work specifically addressed this point (Haesler et al 2006). Again, for cattle, few attempts were made so far to critically evaluate the specificity of the antibody reactions in view of potential cross-reactions due to Toxoplasma gondii or other apicomplexan antibodies (Lally et al 1996;Chahan et al 2003).…”

Serological Survey of Neospora caninum Infection in Cattle Herds From Western Romania

“…0.05). However, the number of dogs per farm was positively associated with N. caninum seroprevalence in cows (P Wald 5 0.043), as previously observed by Paré et al (1998) and Dijkstra et al (2002) and, more recently, by Schares et al (2004) and Hobson et al (2005), although this contradicts several studies that did not find an association between farm dogs and bovine neosporosis (Rodriguez et al, 2002;Fischer et al, 2003). The lack of association between previous DOI: 10.1645/GE-3023.1 abortions and seroprevalence in cows is not surprising considering that a number of factors can influence the abortion in dams (Schares et al, 2004), not least the genetic and biological diversity of field isolates ) and the dam's immunity .…”

Epidemiology and Control of Neosporosis andNeospora caninum

“…The presence of farm dogs, their number, and the frequency of observation of dogs defecating in a feed manger were associated with an increased abortion risk at the herd level (37,218). Other studies failed to identify an association between farm dogs and bovine abortion at the herd level (174,289,376). However, because N. caninum-associated abortions are not always linked to horizontal transmission but also occur in chronically infected dams, it cannot be expected that there is always a positive association between the presence or number of farm dogs and bovine abortion.…”

“…There are a number of casecontrol and cross-sectional studies that have observed that a high N. caninum seroprevalence in herds is associated with an increased risk of abortion at the herd level (37,174,218,339,382,402,488). This is explained by the increased abortion risk in latently infected as well as in recently infected individual dams (see above).…”