Emergence of Mycobacterium orygis-Associated Tuberculosis in Wild Ruminants, India

Tuberculosis in wild animals in India

India is renowned for its complex megadiverse ecosystems and abundant biodiversity. Bovine tuberculosis (bTB) often remains synonymous with Mycobacterium bovis infection in cattle. The domain of tuberculosis (TB) among wild animals, induced by members of the Mycobacterium tuberculosis complex organisms (MTBC), is often underexplored and underreported in India. Within this context, instances of wild animal tuberculosis (wTB) have manifested across both captive and free-roaming animals. The sources contributing to wTB in animals can be human, animal, or environmental factors, thus illuminating the complex transmission pathways. The diagnosis of wTB continues to pose a formidable challenge, a consequence of the expansive taxonomic diversity in both the host and the pathogen. Complications inherent in acquiring samples from wildlife, the absence of standardized diagnostic protocols, limited insights into infection prevalence, and resource constraints compound diagnosis. Amidst these, adopting the comprehensive One Health paradigm surfaces as an imperative, accentuating the interconnectedness bridging human, animal, and environmental health. Recognizing key stakeholders and fostering intersectoral collaboration to provide enhanced diagnostic techniques driven by skilled personnel and advanced infrastructure play pivotal roles in a comprehensive strategy. Additionally, leveraging vaccination efforts contributes to effective control. A national wTB surveillance program is a cornerstone, ensuring an integrated and holistic approach to disease management. Through this review, we delve into the current landscape of wTB in India, unveiling its multifaceted challenges, and further explore the multifarious strategies that the One Health approach proffers in this dynamic endeavor.

Whole genome sequencing and comparative genomics of Mycobacterium orygis isolated from different animal hosts to identify specific diagnostic markers

Introduction

Mycobacterium orygis, a member of MTBC has been identified in higher numbers in the recent years from animals of South Asia. Comparative genomics of this important zoonotic pathogen is not available which can provide data on the molecular difference between other MTBC members. Hence, the present study was carried out to isolate, whole genome sequence M. orygis from different animal species (cattle, buffalo and deer) and to identify molecular marker for the differentiation of M. orygis from other MTBC members.

Methods

Isolation and whole genome sequencing of M. orygis was carried out for 9 samples (4 cattle, 4 deer and 1 buffalo) died due to tuberculosis. Comparative genomics employing 53 genomes (44 from database and 9 newly sequenced) was performed to identify SNPs, spoligotype, pangenome structure, and region of difference.

Results

M. orygis was isolated from water buffalo and sambar deer which is the first of its kind report worldwide. Comparative pangenomics of all M. orygis strains worldwide (n= 53) showed a closed pangenome structure which is also reported for the first time. Pairwise SNP between TANUVAS_2, TANUVAS_4, TANUVAS_5, TANUVAS_7 and NIRTAH144 was less than 15 indicating that the same M. orygis strain may be the cause for infection. Region of difference prediction showed absence of RD7, RD8, RD9, RD10, RD12, RD301, RD315 in all the M. orygis analyzed. SNPs in virulence gene, PE35 was found to be unique to M. orygis which can be used as marker for identification.

Conclusion

The present study is yet another supportive evidence that M. orygis is more prevalent among animals in South Asia and the zoonotic potential of this organism needs to be evaluated.

Clinical features of human tuberculosis due to Mycobacterium orygis in Southern India

Mycobacterium orygis is a member of the Mycobacterium tuberculosis complex (MTBC) and causes tuberculosis in a variety of animals, including humans in South Asia. Here, we describe the clinical features associated with 8 human cases of whole genome sequence (WGS) confirmed M. orygis from a tertiary care hospital in South India during 2018-2019. The patient ages ranged from 9 to 51 years, with 5 females and 3 males included. All the patients had extrapulmonary disease with 2 having concomitant pulmonary involvement. Clinical improvement was documented after a full course of anti-tuberculosis therapy in 6 cases for whom follow-up was available. Taken together, the results show that M. orygis causes human tuberculosis in India, with a predominant extrapulmonary disease. Standardized molecular assays of this emerging member of the MTBC are needed to provide further information on the frequency of M. orygis infection in India and other countries where it is found in livestock and domestic wildlife.