Comparison of host-, herd-, and environmental-factors associated with serpositivity to neospora caninum among adult beef and dairy cattle in alberta

摘要

This study represents an analysis of serological and risk factor data collectedpreviously in Alberta, Canada, involving neosporosis in beef and dairy cattle. Thecausative agent of neosporosis, Neospora caninum (NC), is a single-celled,apicomplexan protozoan parasite in which domesticated dogs have been identified as thedefinitive host. The primary economic impact involves beef and dairy cattle due toassociated abortions and neonatal mortality. The data used in this study were collectedfor cattle in both dairy and beef herds in an identical manner permitting a directcomparison of host-, herd-, and environmental risk factors for neosporosis among beefand dairy cattle using descriptive statistical methods and the construction ofmultivariable models. The outcome assessed in the multivariable models was cow-levelseropositivity for antibodies to N. caninum. Individual-level fixed, herd-level fixed, andrandom effects were evaluated with respect to the outcome. In the final multivariablemodels, there were few statistically significant potential risk factors identified. In thebeef multivariable model, the significant explanatory factors were related to acreage offarm, site of calving, and pH of soil. Among the potential risk factors identified in thethree multivariable models it appeared seropositivity to NC among beef cattle is morerelated to environmental conditions; on the other hand, it seems that seropositivity to NC in dairy cattle pertains to associated management factors. In the future, longitudinalstudies are needed to explore the validity of the current knowledge regarding N. caninumby investigating potential risk factors that have been identified due to the fact that crosssectionalstudies can not prove association.