Serological detection and molecular typing of Mycobacterium avium subspecies paratuberculosis in sheep and goats co-infected with gastrointestinal parasites from the northern Himalayan territories of India.

Abstract

Aim: The present study was conducted to investigate the occurrence of paratuberculosis infection and gastrointestinal (GI) parasitism in small ruminants, including the threatened Changthangi goats of the Ladakh region and to characterize the Map strain diversity and detection of anti-Mycobacterium avium subspecies paratuberculosis (Map) antibodies in serum samples of sheep and goats.

Methods and results: A total of 327 faecal samples were collected from 32 flocks across various locations in the Kashmir and Ladakh regions and were examined for the presence of Map bacilli. Initial screening using Ziehl-Neelsen staining detected acid-fast bacilli in 111 samples (33.9%), of which 88 were confirmed positive for Map by IS900 and IS1311 Polymerase chain reaction (PCR) assays. The overall occurrence of Map infection in sheep and goats was 26.9%. Molecular typing of the 88 PCR-positive samples using IS1311 PCR-restriction enzyme analysis identified the B-type Map in 85 samples (96.5%) while 3 samples (3.4%) belonged to S-type strain; no C-type strains were detected in this study. Sequencing of 13 representative IS1311 amplicons (B-type = 10; S-type = 3) demonstrated that all B-type sequences possessed intact Thymine & Guanine nucleotides at positions 64 and 65, consistent with the US Bison type, while the S-type sequences also showed complete homology, confirming single bison and sheep biotypes circulating in the study population. Additionally, the faecal analysis indicated a high occurrence (85.32%) of GI parasites in small ruminants with Haemonchus spp. being the most prevalent (79.0%), followed by Trichostrongylus spp. (12%). Furthermore, among 150 serum samples collected from 20 flocks in the Kashmir region, enzyme-linked immunosorbent assay (ELISA) detected anti-Map antibodies in 39 (26.0%) samples. At the flock level, 65% were seropositive, while individual-level seroprevalence was 18.0% in sheep and 42.0% in goats.

Conclusion: The study reveals an overall Map infection rate of 26.9% in small ruminants, with the B-type strain as the dominant biotype, exhibiting sequence identity with the US Bison type. ELISA-based seroprevalence was 26.0%, while GI parasitism was widespread, affecting over 85% of animals, with Haemonchus spp. as the predominant parasite affecting sheep and goats.