Tahereh Gholamhosseini Moghaddam - Department of Pathobiology, School of Veterinary Medicine, Shiraz University, Shiraz, Iran.
Masoud Haghkhah - Department of Pathobiology, School of Veterinary Medicine, Shiraz University, Shiraz, Iran.
Gholam Reza Mohammadi - Department of Clinical Sciences, Faculty of Veterinary Medicine, Ferdowsi University of Mashhad, Mashhad, Iran.

Mycobacterium avium subspecies paratuberculosis (MAP) is the causative agent of Johne's disease in wild and domestic ruminants. Clinically, infected cattle show emaciation symptoms, diarrhea, and death. Asymptomatic subclinical cases can intermittently shed MAP through feces and milk and infect other cattle animals, thus increasing the risk of infection. The purpose of the present study was to detect the prevalence of this disease in dairy cattle. For this purpose, ۳۴۸ samples were randomly collected from ۱۵ cattle farms. All fecal samples were subjected to ZN staining and PCR of nucleotide sequences related to specific MAP gene fragments (IS۹۰۰, F۵۷) and were cultured in Harold's egg yolk culture medium after being disinfected with solution (۰.۰% HPC۷۵). PCR testing of ۱۱۶ fecal samples (۳۳.۳%, CI:۹۵% ۲۸.۳-۳۸.۲), ZN staining of ۲۳ samples (۶.۶%, CI: ۹۵% ۴-۹.۲), and fecal sample culture of only ۱۵ samples (۴.۳%, CI:۹۵% ۲.۳-۶.۳,) were infected with MAP. Comparison of test results showed poor agreement (kappa statistic: ۰.۱۹) between ZN staining and PCR results and poor agreement (kappa statistic: ۰.۱۳) between PCR test and fecal culture. This study highlights the advantages of PCR for detecting MAP in subclinically infected cattle compared to ZN staining and fecal culture. Therefore, it can be used for early detection and control of MAP in cattle and at-risk populations.

Johne's disease, Mycobacterium avium subsp. Paratuberculosis, Ziehl-Neelsen, PCR, Iran