Detection of Mycobacterium avium subspecies paratuberculosis in dairy cattle from Shahrekord, Iran

Abstract

Mycobacterium avium subspecies paratuberculosis (MAP) is the causative agent of an incurable intestinal disease in ruminants commonly known as Johne’s disease (JD). This study aimed to evalu-ate the situation of MAP infection from dairy cattle by faecal PCR, milk PCR and milk culture in Shahrekord. In this study, from 19 herds, 80 individual milk and faecal samples were collected from cows of herds suspected to have JD. In addition, 19 tank milk and 19 corresponding environmental faecal samples from the milking parlour were collected. All samples were microscopically assessed; DNA were extracted using the phenol-chloroform method and analysed by IS900-PCR. Finally, milk samples were also cultured on Herold’s Egg Yolk medium (HEYM). Based on microscopic results, eight individual milk (10%), five individual faecal (6.25%), five tank milk (26.3%) and three envi-ronmental faecal (15.8%) samples were positive for acid-fast bacteria. In IS900-PCR, MAP-DNA was detected in six individual milk (7.5%), one individual faecal (1.25%), two tank milk (10.5%) and two environmental faecal (10.5%) samples. MAP cultures were obtained on HEYM from three individual milk and three tank milk samples. Using this study design, six out of the 19 herds were identified as positive for JD. Furthermore, there wass a good agreement between ZN-staining and IS900-PCR (Kappa value 0.66). Sensitivity and negative predictive value of the IS900-PCR was determined as 100%. It can be concluded that serious precautions with respect to JD are needed in Shahrekord.

Keywords

• is900-pcr
• milk
• mycobacterium avium subsp paratuberculosis
• ziehl–neelsen staining