Spatial associations among density of cattle, abundance of wild canids, and seroprevalence to Neospora caninum in a population of beef calves

J Am Vet Med Assoc. 2000 Nov 1;217(9):1361-5. doi: 10.2460/javma.2000.217.1361.

Abstract

Objective: To determine the epidemiologic plausibility of a sylvatic transmission cycle for Neospora caninum between wild canids and beef cattle.

Design: Spatial analysis study.

Animals: 1,009 weaned beef steers from 94 beef herds in Texas.

Procedure: Calves were grouped on the basis of seroprevalence for N caninum and ecologic region in Texas. The Morans I test was used to evaluate spatial interdependence for adjusted seroprevalence by ecologic region. Cattle density (Number of cattle/259 km2 [Number of cattle/100 mile2] of each ecologic region) and abundance indices for gray foxes and coyotes (Number of animals/161 spotlight-transect [census] km [Number of animals/100 census miles] of each ecologic region) were used as covariates in spatial regression models, with adjusted seroprevalence as the outcome variable. A geographic information system (GIS) that used similar covariate information for each county was used to validate spatial regression models. Results-Spatial interdependence was not detected for ecologic regions. Three spatial regression models were tested. Each model contained a variable for cattle density for the ecologic regions. Results for the 3 models revealed that seroprevalence was associated with cattle density and abundances of gray foxes, coyotes, or both. Abundances of gray foxes and coyotes were collinear. Results of a GIS-generated model validated these spatial models.

Conclusions and clinical relevance: In Texas, beef cattle are at increased risk of exposure to N caninum as a result of the abundance of wild canids and the density of beef cattle. It is plausible that a sylvatic transmission cycle for neosporosis exists.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Carnivora / parasitology*
  • Cattle
  • Cattle Diseases / epidemiology
  • Cattle Diseases / parasitology*
  • Cattle Diseases / transmission
  • Coccidiosis / epidemiology
  • Coccidiosis / transmission
  • Coccidiosis / veterinary*
  • Environment
  • Female
  • Foxes / parasitology*
  • Male
  • Models, Biological
  • Neospora / isolation & purification*
  • Regression Analysis
  • Seroepidemiologic Studies
  • Texas / epidemiology