Methemoglobinemia Secondary to Babesia Microti Infection: A Novel Case Report

Background Tick-borne illnesses and methemoglobinemia have not been known to occur together in humans. Few cases have been documented in various animals of methemoglobinemia secondary to tick-borne infections. Case Report A 49-year-old man with no significant medical history presented to the emergency department from an urgent care with hypoxia saturating in the mid 80s. He also reported a pruritic rash on his back and right shoulder as well as both of his lower extremities. The rash had been present for 4 days. The patient was tachycardic and hypoxic at 90% but denied shortness of breath. He had cyanosis of the lips and fingertips and multiple erythematous, raised, ovoid lesions on the right shoulder and left lower extremity. Methemoglobin levels were elevated at 26%. He was treated with methylene blue, supplemental oxygen, and empiric doxycycline with improvement in his oxygenation. A tick-borne illness panel later tested positive for Babesia microti infection. His skin lesions resolved with the above described treatment. Why Should an Emergency Physician Be Aware of This? Both tick-borne illnesses and methemoglobinemia are typically easily treatable with proper antimicrobial coverage and methylene blue, respectively. The current literature is bare regarding concurrent tick-borne illnesses, specifically babesiosis, and methemoglobinemia. Without knowledge and documentation of a potential link between the two conditions, hypoxia, if found to be due to methemoglobinemia, may be treated adequately, but a potentially life-threatening tick-borne illness may continue to cause damage and disease to the patient if not tested for, identified, and treated.