Johne\'s disease (JD) is a chronic enteric infection in ruminants caused by Mycobacterium avium subspecies paratuberculosis (MAP). JD infection is more difficult to diagnose in goats than cattle because MAP can insidiously affect small ruminants. Few reports have used pathological and molecular diagnosis for cases in Korean black goats. Here, we present our results from two MAP-infected goats. Case 1 was categorized as clinically significant (stage IV), with severe clinical signs and a high antibody titer (S/P ratio, 158.9%). Case 2 was in the subclinical stage (stage II); however, the goat suddenly died without any clinical signs (S/P ratio, 70.9%). DNA from the organ tissues and feces from Case 1 showed a strong positive PCR result for MAP, whereas Case 2 only exhibited a very weak reaction in the fecal sample. Moreover, fecal DNA from both cases was genotyped as C-type MAP using the PCR-REA method. Gastrointestinal organ tissues (jejunum, ileum, colon, and mesenteric lymph nodes) from Case 1 showed moderate-to-severe lesions, and acid-fast bacilli were observed. In contrast, Case 2 showed intact-to-mild pathological lesions, and acid-fast bacilli were detected in the colon, mesenteric lymph nodes, and liver. In addition, Case 2 was co-infected with Corynebacterium pseudotuberculosis, which caused caseous lymphadenitis. This case study provides valuable information regarding the pathological and molecular characteristics of JD-infected Korean black goats. The results highlighted the differences in pathological lesions between clinically and subclinically infected goats, which help veterinarians to develop better strategies to control MAP in goat farms.

Correctly identifying bovine tuberculosis (bTB) in cattle remains a significant problem in endemic countries. We hypothesized that animal characteristics (sex, age, breed), histories (herd effects, testing, movement) and potential exposure to other pathogens (co-infection; BVDV, liver fluke and Mycobacterium avium reactors) could significantly impact the immune responsiveness detected at skin testing and the variation in post-mortem pathology (confirmation) in bTB-exposed cattle. Three model suites were developed using a retrospective observational data set of 5,698 cattle culled during herd breakdowns in Northern Ireland. A linear regression model suggested that antemortem tuberculin reaction size (difference in purified protein derivative avium [PPDa] and bovine [PPDb] reactions) was significantly positively associated with post-mortem maximum lesion size and the number of lesions found. This indicated that reaction size could be considered a predictor of both the extent (number of lesions/tissues) and the pathological progression of infection (maximum lesion size). Tuberculin reaction size was related to age class, and younger animals (<2.85 years) displayed larger reaction sizes than older animals. Tuberculin reaction size was also associated with breed and animal movement and increased with the time between the penultimate and disclosing tests. A negative binomial random-effects model indicated a significant increase in lesion counts for animals with M. avium reactions (PPDb-PPDa < 0) relative to non-reactors (PPDb-PPDa = 0). Lesion counts were significantly increased in animals with previous positive severe interpretation skin-test results. Animals with increased movement histories, young animals and non-dairy breed animals also had significantly increased lesion counts. Animals from herds that had BVDV-positive cattle had significantly lower lesion counts than animals from herds without evidence of BVDV infection. Restricting the data set to only animals with a bTB visible lesion at slaughter (n = 2471), an ordinal regression model indicated that liver fluke-infected animals disclosed smaller lesions, relative to liver fluke-negative animals, and larger lesions were disclosed in animals with increased movement histories.