Among the 8 study herds, only 4 were infected, and
a significant difference was seen in serum and milk ELISA
results between infected and noninfected herds (P , 0.001).
Furthermore, agreement among tests was higher in the
more heavily infected herds; therefore, herd infection status
was reflected in the serum and milk ELISA results
(Table 1). The infected herds were generally larger,
managed intensively, and systematically violated most
recommendations for control of paratuberculosis by herd
management, including routine introduction of animals of
unknown paratuberculosis test status from herds of
unknown MAP infection status. 5,16 These herds experi-
enced clinical cases of paratuberculosis and even mortalities
caused by the disease.