Clinical and molecular investigation of johne’s disease among small ruminants in Makkah, Saudi Arabia

Abstract

Paratuberculosis (PTB) or Johne’s disease (JD) is a chronic debilitating disease caused by the Mycobacterium avium subsp . paratuberculosis (MAP). JD affects a wide range of animals including ruminants and characterized by enteritis and progressive diarrhea. The current study aimed to implement molecular tools for detection and identification of MAP among clinically suspected small ruminants in Makkah region, Kingdom of Saudi Arabia (KSA). A total of 2660 small ruminants from five different farms around Makkah were clinically investigated for characteristic signs of JD during the period of November 2013 to February of 2014. Out of investigated animals, 16 cases were selected as being suspected of JD infection based on the associated clinical symptoms (emaciation and unthriftiness with or without persistent diarrhea). Rectal scrapings were collected from all suspected animals and were subjected for molecular examination. Three different genetic targets were evaluated including 16S rDNA, insertion sequence 900 (IS900) and intergenic spacer (IGS). Initial examination of suspected specimens by amplification of universal bacterial primers for 16S rDNA revealed positive results in 6 out of 16 cases (37.5%). Further amplification of the Mycobacterium -specific IGS target from 16s rDNA-positive samples revealed the detection of 4 Mycobacterium species. Sequence analysis of the IGS sequence of these 4 Mycobacterium species revealed 2 cases only as Mycobacterium avium paratuberculosis . This finding was confirmed by the detection of MAP-specific IS900 target only from the same 2 cases. In conclusion, the current study genetically documented the first report of MAP (the causative agent of JD) among small ruminants of Makkah region.