Pulmonary tuberculosis with secondary aspergillosis in a captive Asian elephant (Elephas maximus): A case report

Introduction

Tuberculosis in captive elephants represents a complex intersection of infectious disease, public health concern, and animal welfare challenge. Since its recognition as a re-emerging zoonotic condition, TB has posed persistent difficulties in early detection, clinical management, and containment within captive populations (Mikota et al. 2000; Mikota 2008) [6,5] . Elephants often present with non-specific, insidious clinical signs, including gradual weight loss, anorexia, intermittent respiratory distress, and behavioural changes frequently leading to delayed diagnosis and advanced disease at presentation (Fowler & Mikota 2006; Lyashchenko et al. 2006) [2,4] . Pathologically, tuberculosis is characterized by granuloma formation, caseation, and progressive pulmonary destruction (Mikota et al. 2000) [6] . Chronic infection compromises host immunity, predisposing affected individuals to secondary opportunistic infections, notably aspergillosis, which further exacerbates respiratory dysfunction (Tell 2005; Beernaert et al. 2010) [7,1] . Despite increasing recognition of tuberculosis in elephants, documented cases involving concurrent fungal infections remain limited, particularly in the Indian context. Such coinfections not only complicate diagnosis and treatment but also significantly worsen clinical outcomes. This case report aims to present a clinically and pathologically comprehensive account of pulmonary tuberculosis with secondary aspergillosis, while emphasizing the critical welfare implications, diagnostic gaps, and need for early intervention strategies in captive elephant management Methodology A 15-year-old female Asian elephant, previously used in circus conditions and subsequently rehabilitated at the Elephant Conservation and Care Centre (Wildlife SOS, India), was monitored longitudinally. Clinical observations began in June 2023 with progressive weight loss and osteoarthritic changes. Body weight was recorded using a calibrated electronic scale, and body condition scoring (BCS) was conducted following established visual assessment criteria (Wijeyamohan et al. 2014) [10] . By November 2024, the animal developed gastrointestinal disturbances, anorexia, and progressive systemic decline. In January 2025, advanced respiratory distress, mucopurulent trunk discharge, and behavioural signs of discomfort were evident. Comprehensive hematological and biochemical analyses were performed. Serological testing for MTBC was conducted using the MycoPac Dual Kit (CisGEN Biotech Discoveries Pvt. Ltd., Tamil Nadu, India), while repeated triple trunk wash cultures were attempted in accordance with standard tuberculosis surveillance protocols (USAHA 2012) [9] . Despite intensive clinical management, the animal succumbed to disease progression. A full necropsy was conducted, with tissue samples submitted for histopathology, Ziehl-Neelsen staining, molecular diagnostics, and fungal culture.

Results and Discussion Clinical progression and systemic decline

The elephant demonstrated a marked decline in body condition, with weight reduction from 3440 kg (BCS 7/10; Fig. 1a) to 2510 kg (BCS 4/10; Fig. 1b), reflecting chronic disease progression and sustained metabolic compromise. Hematobiochemical findings indicated progressive anemia, significant hepatic enzyme elevation, renal compromise and systemic inflammatory response. These findings collectively suggest multi-organ involvement, consistent with chronic infectious disease and prolonged physiological stress. The detailed hematobiochemical parameters are presented in Table 1. Repeated triple trunk wash cultures were negative, consistent with previous reports highlighting the limited sensitivity of trunk wash culture in early or latent stages of tuberculosis in elephants (Mikota et al. 2000; Greenwald et al. 2009) [3,6] . In contrast, serological testing demonstrated strong reactivity (Fig. 2), supporting the growing evidence that serology and molecular diagnostics are essential tools for early and reliable detection (Lyashchenko et al. 2006) [4] .

Therapeutic Limitations

Despite initiation of anti-tubercular therapy (INH and PZA), clinical response was poor. This highlights a critical reality that in elephants, therapeutic success is heavily dependent on early diagnosis. Advanced-stage disease is often refractory to treatment (Fowler & Mikota 2006) [2] . Challenges such as poor drug acceptance and advanced pathology further complicate management.

Pathological findings and disease severity: Post-mortem examination revealed extensive pulmonary cavitation, diffuse caseous granulomas, severe pulmonary destruction (Fig. 3). Cytological examination of impression smears further demonstrated clusters of acid-fast bacilli (Fig. 4), histopathology confirmed chronic active tuberculosis, while PCR identified Mycobacterium orygis, an emerging pathogen of regional importance. The presence of Aspergillus spp. within necrotic lung cavities is particularly significant, indicating severe immunosuppression, advanced disease stage and compounded respiratory dysfunction.

Welfare Interpretation

This case exemplifies the silent progression of chronic disease in captive elephants, where clinical signs often become evident only at advanced stages. Key welfare concerns include; prolonged undetected suffering, chronic systemic stress, reduced quality of life due to respiratory compromise and metabolic decline and co-morbid conditions such as osteoarthritis likely contributed to immunosuppression, further accelerating disease progression.

Conclusion

This case highlights pulmonary tuberculosis caused by Mycobacterium orygis, complicated by secondary aspergillosis, in a captive Asian elephant. The findings emphasize:

1) the chronic and insidious nature of tuberculosis in elephants, 2) the limitations of conventional diagnostics, 3) the critical role of opportunistic infections in disease severity, and 4) the urgent need for early, proactive disease surveillance systems.

Key Recommendations

Key recommendations for veterinary and management practice include: 1) implementation of routine TB surveillance using serological and molecular tools, 2) development of standardized health monitoring protocols for captive elephants, 3) early identification and management of co-morbid conditions, 4) strengthening biosecurity and zoonotic risk mitigation measures, and adoption of a preventive, welfare-centered veterinary approach.

Final impact statement

Early detection is not merely a diagnostic goal-it is a welfare obligation. In captive elephants, timely intervention defines the difference between managed disease and prolonged, silent suffering.

Acknowledgement

AcknowledgmentsThe authors gratefully acknowledge the guidance and institutional support of Kartick Satyanarayan, CEO and Co-Founder, and Geeta Seshamani, Co-Founder and Secretary, Wildlife SOS. The authors also acknowledge Baijuraj M.V., Director of Conservation Projects, Wildlife SOS, for his support. Sincere appreciation is extended to the Uttar Pradesh Forest Department for their cooperation and assistance. The authors further recognize the dedicated efforts of the animal care staff at Wildlife SOS for their contribution to the clinical management of the case.

References

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