| dc.description.abstract | Johne’s disease is a chronic and debilitating disease of cattle caused by infection
with Mycobacterium avium subsp. paratuberculosis (Mptb). This disease affects both
dairy and beef cattle, though it is more commonly recognized in dairy cattle. Mptb is
able to persist in the environment of cattle for extended periods of time; therefore the
distribution of the disease depends on the presence of infected animals and
environmental conditions. Three surveillance systems were used to describe the spatial
distribution of Johne’s disease seropositivity in Texas cattle. These three systems were
hypothesized to describe different spatial patterns. These systems involved sampling, 1)
herds throughout Texas, 2) market cattle from four markets each month (one each from
northern, southern, eastern, and western regions of Texas) and 3) sick animals submitted
by veterinarians throughout Texas. Samples were tested for Johne’s disease at the Texas
Veterinary Medical Diagnostic Laboratory using serum ELISA. Spatial distributions
were estimated by kriging the sample-to-positive control ratios (S/P). Sera were
evaluated for Mptb antibodies from 2358 cattle with 1084 animals in system 1, 1200
from system 2 and 74 from system 3. Total number of positive ELISA results was 51,
with 25, 19 and 7 positve ELISA results for systems one, two and three, respectively. Results showed an overall prevalence of 2.16%, and prevalence’s of 2.31%, 1.58% and
9.46% for systems one, two and three, respectively. Differences in the spatial
distribution of Johne’s disease seropositvity, based on the three surveillance systems,
confirmed our hypothesis that estimation of disease distribution is dependant upon the
source of surveillance samples. | en |
