Towards evaluating the economic impact of bovine neosporosis

In spite of the global importance of neosporosis as a cause of bovine abort ion, there is very little information about its economic consequences. The economic costs are a product of estimations of the quantity of the effects attributable to Neospora infection, and the particular unit costs of those effects. In this brief review, which arose from a workshop on the economics of coccidiosis held at the COST 820 meeting, Toledo 1998, we discuss the p ossible effects of neosporosis which are of economic significance and summa rise the available estimates of their magnitude to provide a basis for furt her economic analysis. Neospora infection has been associated with abortion , increased culling and reduced milk yield. In addition, it has been diagno sed in cases of stillbirth and neonatal mortality, it is likely to contribu te to early foetal death and resorption and it is responsible for a reducti on in the value of female breeding cattle. In quantifying the role of Neosp ora, it is important that epidemiologically based, case-controlled studies are conducted because, given the extreme efficiency with which bovine Neosp ora infection is vertically transmitted, demonstration of prevalence of inf ection in affected animals (including foetuses) is not a true indicator of the significance of this disease. Relatively few epidemiological studies ha ve been conducted, but in investigations in the USA, Holland and Britain, i nfected cows have been shown to be about three times more likely to abort t han non-infected cattle. In the UK this approach has been used to estimate the proportion of abortions in the national dairy population which may be a ttributable to Neospora caninum. (C) 1999 Australian Society for Parasitolo gy Inc. Published by Elsevier Science Ltd. All rights reserved.