Submitted to: Australian Veterinary Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/23/2007
Publication Date: N/A
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, antibody-mediated staining technique along with pathologic study of the tissue from infected sheep are evaluated as methods of detection of infection in sheep flocks 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 sheep. This paper is a premier paper demonstrating a high prevalence of paratuberculosis in sheep in Jordan. Being able to accurately detect infected animals will help allay the spread of this disease.
Technical Abstract: Paratuberculosis (Johne’s disease) is an incurable infectious, chronically progressive enteric disease affecting domestic and exotic ruminants. The causative agent is Mycobacterium Avium Paratuberculosis. In this study the occurrence of subclinical Johne’s disease in Awassi sheep is investigated. Out of twenty sheep flocks surveyed, eighteen had untreatable bottle jaw and fifteen had emaciation. The emaciation was associated with intermittent and untreatable diarrhea. Histopathological examination of 202 ilea and the corresponding mesenteric lymph nodes was conducted. In addition, immunohistochemical examination using rabbit polyclonal antisera of 134 ilea and 83 mesenteric lymph nodes was also conducted. The prevalence of the disease was 97% and 93% using histopathology and immunohistochemistry (IHC) techniques, respectively. When the lymph nodes were tested, it was revealed that 79% of them were positive by IHC. The histopathological lesions were graded from I-IV, I being the least severe, based on the type of cellular infiltrate (lymphocytes, macrophages and epithelioid cells) and the severity of the lesions. Analysis of the results revealed that most positive cases were in grades I and II. Furthermore, the IHC reactions were classified into three types depending on the number of stained cells and the intensity of the staining (mild, moderate and strong). These results showed that subclinical paratuberculosis in sheep is very prevalent in Jordan. It is interesting to note that this is the first study of Johne's disease in sheep in Jordan and results strongly suggest alarming fears of severity of the disease at the national level.