Tick-borne anaplasmosis and myocarditis in eastern Ontario

Key points• Anaplasmosis is the second most common tick-borne disease in Canada, with rapidly rising incidence owing to the expanding geographic distribution of Ixodes scapularis.• Anaplasmosis should be suspected when patients living in endemic regions present with fever, malaise, headache, and gastrointestinal symptoms, even if they do not recall any tick bites.• Infection with end-organ complications is less common and can include myocarditis, encephalitis, acute respiratory distress syndrome, and acute renal failure.• Early recognition and empiric treatment of anaplasmosis with doxycycline can prevent associated life-threatening complications.