Johne's disease

Seroprevalence of Mycobacterium avium subspecies paratuberculosis in Florida beef and dairy cattle.

Abstract

The objective of this study was to estimate the prevalence of M. avium subsp. paratuberculosis infection among beef and dairy cattle in Florida, USA. This was a retrospective seroprevalence study on serum samples from 32?011 cattle originating from 75 herds. Selection was limited to whole herds being tested for diagnostic purposes by owners considering participation in the voluntary Johne's Control Programme or the voluntary Florida Johne's Disease Herd Status Programme. Data were obtained from the Florida State Veterinary Diagnostic Laboratory and USDA-APHIS statewide submission of specimens for Johne's testing from 1999 to 2001. Specimens were evaluated using a commercial IDEXX ELISA kit with a published sensitivity and specificity of 50 and 99%, respectively. Overall prevalence in the sample population was 6.5%; prevalence in beef and dairy cattle was 7.4 and 6.3%, respectively. 83% of herds included in the study had one or more positive cows in the herd. Larger herds (>100 head) had statistically higher herd prevalence than herds with less than 100 cattle. The true prevalence estimate was calculated to be 11.2%. Although within-herd prevalence was lower than previously reported in Florida, seroprevalence appears to be widely distributed and pervasive among Florida cattle. Our findings suggest there could be 168?000 or more cattle in Florida infected with the organism. There is a need for increased awareness of the disease and implementation of control methods appropriate for each individual herd.