Haemophilus parainfluenzae endocarditis presenting with symptoms of COVID-19

A young man presented early in the UK's second COVID-19 pandemic surge with a twelve-day history of fever, dry cough, breathlessness, myalgia and loss of smell and taste. His chest X-ray showed bilateral ground-glass opacities. He was treated for COVID-19 pneumonitis but covered for bacterial infection with antibiotics. He developed shock and respiratory failure, requiring vasopressors and continuous positive airway pressure. He improved but experienced transient visual disturbances and headache. Nasopharyngeal swabs and antibody tests for COVID-19 were negative. Blood cultures grew Haemophilus parainfluenzae A new murmur prompted an echocardiogram. This confirmed a large, mobile mitral valve vegetation. An MRI of the brain showed bilateral embolic infarcts. He underwent urgent mitral valve repair and made an excellent recovery. Whether COVID-19 caused his presenting symptoms or facilitated the bacteraemia remains unclear. It seems more likely that infective endocarditis masqueraded as COVID-19. Clinicians should be aware of how context of the pandemic can bias diagnostic reasoning.