Comparative diagnostic evaluation and molecular typing of Mycobacterium avium subsp. Paratuberculosis in dromedary camels of Rajasthan, India.

Abstract

Mycobacterium avium subsp. paratuberculosis affects dairy animals (Animal paratuberculosis or Johne's disease) and humans (Human paratuberculosis or Crohn's disease). The dromedary camel (Camelus dromedarius) is a valuable livestock in arid regions, providing milk, meat, leather, and other products, in addition to being used as a pack animal. The study aims to examine the risk potential and molecular strain typing of Mycobacterium avium subsp. paratuberculosis (MAP) in dromedary camels raised in Rajasthan, India- a region with the highest camel population in the country. Faecal samples (88) were collected from six districts: Bikaner, Jaisalmer, Churu, Jodhpur, Nagaur, and Sirohi. From collected faecal samples, 45.45% tested positive for acid-fast bacilli in ZN staining. However, only 14.77%, 26.13%, and 18.18% were positive for MAP in the IS900 PCR, SYBR Green Real-Time (RT) PCR, and faecal culture tests, respectively. SYBR Green RT-PCR has demonstrated greater sensitivity in detecting low levels of MAP presence. A combination of faecal culture and SYBR Green RT-PCR targeting the IS900 gene amplification demonstrated high sensitivity and specificity in the diagnosis of MAP in camels. Molecular strain typing revealed that all MAP isolates were 'Indian Bison Type'. The study suggests a potentially high occurrence of subclinical MAP infections in Indian dromedary camels. However, affected animals were largely asymptomatic, and typical clinical signs of Johne's disease, such as loose feces or diarrhea, were not recorded in any animal. Therefore, continuous monitoring of subclinical MAP infections in dromedary camels is essential for effectively implementing MAP control programs and safeguarding animal and human health.