|Rezig, Feth Eddine|
Submitted to: Comparative Clinical Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/8/2011
Publication Date: 10/1/2012
Citation: Hailat, N., Hemida, H., Hananeh, W., Stabel, J.R., Rezig, F., Jaradat, S., Al-Saleh, A. 2012. Investigation on the occurrence and pathology of paratuberculosis (Johne's disease) in apparently healthy cattle in Jordan. Comparative Clinical Pathology. 21(5):879-888. Interpretive Summary: Johne's disease is a chronic, debilitating intestinal disorder in cattle, sheep, and wild ruminants, characterized by diarrhea, reduced feed intake, weight loss, and death. Animals usually become infected when they are young by ingesting feces containing the causative bacteria. However, symptoms of disease do not usually present themselves until the animals reach 3 to 5 years of age or even older. During this time the animal is infected and may be shedding the organism in its feces without showing any clinical signs of disease. In addition to reduced production by these animals through reduced milk production, they also present a potential infective threat to the rest of the herd. Johne’s disease is difficult to diagnose and therefore to control. Development of accurate and sensitive diagnostic tests is essential for controlling the spread of this disease. In this paper, an antibody-mediated staining technique along with the pathologic study of the tissue from infected cattle was evaluated as methods of detection of infection in cattle populations in Jordan. Results of this study demonstrate that the evaluation of presence of lesions in the tissue is a very sensitive method for the detection of paratuberculosis in cattle. This paper is a premier paper demonstrating a high prevalence of paratuberculosis in cattle in Jordan. Being able to accurately detect infected animals will help allay the spread of this disease.
Technical Abstract: Paratuberculosis (Johne’s disease) is infectious, incurable, chronically progressive granulomatous enteritis which affects domestic and exotic ruminants. The causative agent is Mycobacterium avium paratuberculosis (M. Johnei), a slow growing mycobactin-dependent acid-fast bacillus. We investigated the occurrence of Johne’s disease in apparently healthy cattle, using 263 ileum and corresponding mesenteric lymph nodes, by histopathological examination, and 170 ileum and 120 mesenteric lymph nodes by immunohistochemical examination. The occurrence of the disease was 65% and 66% using immunohistochemistry and histopathology techniques respectively. When ZN and ELISA techniques were implemented, the occurrence was 1% (4/120) and 3% (8/278), respectively. Grading from I-IV of histopathological lesions based on type of cellular infiltrate and severity of lesions revealed that most of the positive cases in grade I and II. Furthermore staging I-III of immunohistochemistry results, has presented a high number of positive cases in stage I. ZN stain showed a very low occurrence; however, it is still used as a confirmatory test for clinical cases. On the other hand, ELISA technique showed a low occurrence of the disease (3%) in this study reflecting the low sensitivity of the technique in diagnosis of subclinical JD. These results showed that histopathology is a very good diagnostic method for subclinical paratuberculosis in cattle. From the present study, we conclude that the occurrence of JD in cattle is high in Jordan. It is interesting to note that this is the first study of JD in cattle in Jordan and the results strongly suggest alarming fears of severity of the disease at the national level. The urgent need for national control strategies are well founded due to the economical importance of the disease.