Differential Diagnosis in the Age of COVID-19 and the Need to Maintain a Broad Differential

Abstract

During the coronavirus pandemic, patients admitted to emergency departments (ED) with constitutional symptoms, respiratory complaints, and/or history of sick contacts have high clinical suspicion for COVID-19 regardless of whether initial screening tests are negative. Although communities seek daily coronavirus infection rates of less than one percent, physicians can be highly focused on narrow differentials despite adequate history and physical exams. This case report focuses on an elderly patient with a past medical history of hypertension, chronic kidney disease (CKD), and gout who presented with three days of fevers, chills, body aches, and shortness of breath and reported a home oxygen saturation of 89%. The patient was a health care worker with high risk of contracting COVID-19, and on admission was febrile and found to have lymphopenia. Nevertheless, COVID-19 Polymerase Chain Reaction (PCR) testing returned negative on two separate occasions prompting the team to broaden their differential. Leukopenia, thrombocytopenia and mildly elevated transaminases can all be due to COVID-19, but should also lead medical teams to include tick-borne illnesses as a potential etiology. Parasite serology returned positive for Babesia microti via IgG antibodies (1:512) and Anaplasma phagocytophilum via PCR and the patient was discharged on appropriate antimicrobial therapy. It is important for providers to understand and recognize the following: 1) overlapping symptoms of tick-borne disease and COVID-19, 2) proper diagnosis and management of babesiosis and anaplasmosis, and 3) benefits of broad differentials for patient care during the COVID-19 pandemic.