Evaluation of environmental sampling to determine distribution and herd infection status for Mycobacterium avium subspecies paratuberculosis

A total of 483 environmental samples were collected from 98 dairy operations; 216 (44.7%) were culture positive for Mycobacterium avium subspecies paratuberculosis (MAP). The hi ghest percentage of positive environmental samples were collected from parlor exits (52.3%), holding pen floors (49.1%), common alleyways (48.0%), lagoons (47.4%) and manure spreaders (42.3%). Of the 98 operations tested with environmental sample culture, also obtained were individual fecal culture results from 60, individual serum ELISA from 97 and individual milk ELISA from 34. Of the 50 herds classified as infected by fecal culture, 38 (76.0%) were identified by environmental culture. Two of the 10 op erations classified as not infected based on individual animal fecal culture were environmental culture positive. Of the 80 operations classified as infected based on serum ELISA positive test results, 61 (76.3%) were identified as environmental positive. Environmental sample collection and culture is more cost effective than individual animal sampling and identified more than 75% of infected operations in this study. Environmental sampling is another diagnostic tool that veterinarians and dairy producers can use to determine herd MAP infection status.