Healthy or unhealthy? Risk factors and biomarkers associated with exposure to infectious agents in wild lowland tapirs (Tapirus terrestris)

Context Links between tapir health and environmental conditions are well-established, but substantial knowledge gaps on biological and environmental causes of ill-health remain. Furthermore, anthropogenic impacts and climate change effects on disease patterns are escalating issues. Aims Our study aimed to build on earlier research on wild lowland tapir (Tapirus terrestris) health and investigate risk factors and potential consequences associated with infectious agents. Methods Between 2008 and 2018, 174 samples from 115 wild lowland tapirs across two contrasting locations in Brazil were screened for four infectious agents (bluetongue virus, porcine parvovirus, Leptospira interrogans serovar Pomona, and Trypanosoma terrestris), along with clinical and haematological findings. Generalised linear models and boosted regression trees were applied to evaluate associations with risk factors, likely disease consequences, and meteorological conditions. Key results Tapirs in human-modified areas presented higher risk of exposure to livestock pathogens such as bluetongue virus (relative influence (RI) 94.2%) and porcine parvovirus (RI 58.5%), whereas those in pristine habitats exhibited higher risk to Trypanosoma terrestris (RI 92.5%) and Leptospira sp. (RI 39.9%). Bluetongue cases increased from one in Year 2 to 35 in Year 10 (odds ratio 2.90, 95% CI 2.12–3.97, P < 0.001). Significant associations were found between infectious agents and pale mucous membranes (RI 85.5%), high tick burden (RI 78.4%), low red (RI 78.3%) and high white (RI 38.1%) blood cell counts, and presence of wounds (RI 59.1%). Poor body condition was weakly linked to all variables. Elevated alkaline phosphatase, glucose, and total protein levels demonstrated associations with infectious agents, whereas high creatine kinase was linked to capture-related stress. No significant associations with meteorological data were detected. Conclusions Our study highlighted the complex influence of biological and environmental conditions on infectious disease dynamics in tapirs. Location emerged as the main risk factor for pathogen occurrence, with biomarkers such as heavy tick burden, pale mucous membranes, presence of wounds, high white blood cell count, and low red blood cell count representing key indicators of tapir health. Implications Our research has provided robust scientific evidence addressing long-standing hypotheses on tapir health, supporting practical applications and informing wildlife management and disease surveillance research.