Validation of a serum ELISA test for cyathostomin infection in equines.

Cyathostomins are ubiquitous equine nematodes. Infection can result in larval cyathostominosis due to mass larval emergence. Although faecal egg count (FEC) tests provide estimates of egg shedding, these correlate poorly with burden and provide no information on mucosal/luminal larvae. Previous studies describe a serum IgG(T)-based ELISA (CT3) that exhibits utility for detection of mucosal/luminal cyathostomins. Here, this ELISA is optimised/validated for commercial application using sera from horses for which burden data were available. Optimisation included addition of total IgG-based calibrators to provide standard curves for quantification of antigen-specific IgG(T) used to generate a CT3-specific 'serum score' for each horse. Validation dataset results were then used to assess the optimised test's performance and select serum score cut-off values for diagnosis of burdens above 1000, 5000 and 10,000 cyathostomins. The test demonstrated excellent performance (Receiver Operating Characteristic Area Under the Curve values >0.9) in diagnosing infection, with >90% sensitivity and >70% specificity at the selected serum score cut-off values. CT3-specific serum IgG(T) profiles in equines in different settings were assessed to provide information for commercial test use. These studies demonstrated maternal transfer of CT3-specific IgG(T) in colostrum to newborns, levels of which declined before increasing as foals consumed contaminated pasture. Studies in geographically distinct populations demonstrated that the proportion of horses that reported as test positive at a 14.37 CT3 serum score (1000-cyathostomin threshold) was associated with parasite transmission risk. Based on the results, inclusion criteria for commercial use were developed. Logistic regression models were developed to predict probabilities that burdens of individuals are above defined thresholds based on the reported serum score. The models performed at a similar level to the serum score cut-off approach. In conclusion, the CT3 test provides an option for veterinarians to obtain evidence of low cyathostomin burdens that do not require anthelmintic treatment and to support diagnosis of infection.

National estimates of racial segregation in rural and small-town America.

The objective of this paper is to provide, for the first time, comparative estimates of racial residential segregation of blacks, Hispanics, and Native Americans in nonmetropolitan and metropolitan places in 1990 and 2000. Analyses are based on block data from the 1990 and 2000 U.S. decennial censuses. The results reveal a singularly important and perhaps surprising central conclusion: levels and trends in recent patterns of racial segregation in America's small towns are remarkably similar to patterns observed in larger metropolitan cities. Like their big-city counterparts, nonmetropolitan blacks are America's most highly segregated racial minority--roughly 30% to 40% higher than the indices observed for Hispanics and Native Americans. Finally, baseline ecological models of spatial patterns of rural segregation reveal estimates that largely support the conclusions reached in previous metropolitan studies. Racial residential segregation in rural places increases with growing minority percentage shares and is typically lower in "new" places (as measured by growth in the housing stock), while racially selective annexation and the implied "racial threat" at the periphery exacerbate racial segregation in rural places. Our study reinforces the need to broaden the spatial scale of segregation beyond its traditional focus on metropolitan cities or suburban places, especially as America's population shifts down the urban hierarchy into exurban places and small towns.