A Rare Case Report of COVID-19 and Leptospirosis Co-infection Triggering Acute Myocarditis

Leptospirosis is a globally prevalent zoonotic infection, more common in tropical climates but increasingly recognised in temperate regions, such as the United Kingdom. Its clinical presentation varies widely, ranging from mild flu-like symptoms to severe complications including pulmonary haemorrhage and multi-organ failure, making diagnosis challenging. We report the case of a 25-year-old male who presented with a three-day history of fever, myalgia, non-productive cough, and shortness of breath. He tested positive for SARS-CoV-2 and was diagnosed with COVID-19 pneumonitis. His condition deteriorated, necessitating ICU admission and mechanical ventilation. During his ICU admission, he suffered complications such as pulmonary haemorrhage, a known complication of leptospirosis. Despite initial management with corticosteroids and broad-spectrum antibiotics, his liver function worsened, and echocardiography showed reduced ejection fraction with elevated troponin, suggesting myocarditis. A leptospirosis screen was sent and returned positive on day 14. Retrospective history revealed exposure to rats in his residence. The patient was started on oral doxycycline, which led to steady clinical improvement and eventual discharge. This case highlights the diagnostic difficulty in distinguishing leptospirosis from COVID-19 due to overlapping features. Early signs-including deranged liver function, pulmonary haemorrhage, and cardiac involvement-were present but not initially attributed to leptospirosis. Delayed consideration of zoonotic exposure contributed to a delay in targeted therapy. Clinicians should maintain a high index of suspicion for leptospirosis in patients presenting with multi-organ involvement, particularly in the setting of potential environmental exposure. Early diagnosis and initiation of appropriate antimicrobial therapy are vital to improving patient outcomes.