A Study on the Prevalence of Mycobacterium avium paratuberculosis in Three breeds of Sheep at Ahvaz Abattoir

This survey was carried out to determine the prevalence of Mycobacterium avium paratuberculosis in Ahvaz abattoir، khozestan، Iran. From a pathological examination of the intestinal tracts of 1950 sheeps killed at slaughterhouse، 111 cases (5. 69%) were suspected on gross examination، for having paratuberculosis. The diagnosis was confirmed by histopathological study and Ziehl-Neelsen staining on direct smears of rectal faeces. High numbers of acid-fast organisms were present in epithelioid macrophages of both intetestine and mesenteric lymph nodes. On microscopic examination، 18. 02 % of the suspected animals (111 cases) were found to have paratuberculosis in comparison with 6. 3 % by direct faecal smears. In addition، 37. 83% and 13. 51% and 4. 5% of the animals were diagnosed as having eosinophilic enteritis، lymphocytic enteritis and suppurative enteritis، respectively. Infection rate in arabian breed (0. 56%) was higher comparing to the rate in Lori (0. 21%) and Bakhtiari breed (0. 26%)، however differences between sheep breeds were not statistically significant (P=0. 34). The age specific infection rates among age groups were not significant (P=0. 59). Significant association was found between caracass condition and the rate of infection recated to Mycobacterium avium paratuberculosis (P<0. 001). According to the histopathology results، the prevalence of Johne''s disease in Ahvaz abattoir is 1. 03 % which correlates with previously published estimates.