A tale of "ticked" lung: a case report of anaplasmosis presenting as respiratory failure

SESSION TITLE: Chest Infections Case Report Posters 4 SESSION TYPE: Case Report Posters PRESENTED ON: 10/09/2023 12:00 pm - 12:45 pm INTRODUCTION: Anaplasmosis is a known tick-related illness caused by an intracellular bacterium Anaplasma phagocytophilum. The common presentation includes myalgias, fever, leukopenia, and thrombocytopenia. Complications like myocarditis, encephalitis, and pneumonitis are rare and are usually in immunocompromised patients. We present a case of anaplasmosis-related respiratory failure requiring mechanical ventilation in an immunocompetent patient. CASE PRESENTATION: A 58 yr old female with a history of supraventricular tachycardia presented to ED with 2 days of shortness of breath. Upon presentation, her heart rate was in the 150s with an oxygen saturation of 64% on room air requiring a rescue BIPAP. Her blood work at admission was positive for mild lymphopenia and thrombocytopenia, while the chest x-ray showed bilateral patchy opacification. The clinical picture supported a viral etiology, but we empirically covered her with antibiotics. In the next two days, her breathing worsened, requiring mechanical ventilation. Diagnostic workup including blood culture, sputum culture, and respiratory panel remained negative while peripheral blood film showed intracellular organisms. We replaced ceftriaxone and azithromycin with doxycycline due to strong suspicion of a tick-borne illness that was later proved by a positive PCR. Gradually patient improved, she was successfully extubated and was discharged from the hospital on oral doxycycline. DISCUSSION: Most infections of human Anaplasmosis are mildly symptomatic however upto 36% require hospitalization with 3% suffering from life threatening complications. Complications, including ARDS and respiratory failure, have been reported in the literature, but they are rare and the association has not been well understood. As an intracellular organism Anaplasma can decrease the phagocytic activity of neutrophils and simultaneously increases inflammatory interleukins production including IL8 and IL10 producing a picture-like cytokine storm. At the same time the bacteria can continue to survive inside of neutrophils by inhibiting apoptotic functions and antimicrobial function. Simply speaking the host deals with an exaggerated immune response with a dysfunctional defense mechanism. Currently, doxycycline is the preferred treatment usually given up to 10 days, while rifampin can be given in patients who have allergies to tetracycline. Although steroids have shown benefits in managing cytokine mediated injury, but their role is not well studied in anaplasmosis related pneumonia and ARDS. CONCLUSIONS: Anaplasmosis-induced pneumonia should be considered in patients who present with atypical pneumonia and do not improve with empiric coverage.The pathophysiology is very similar to COVID-19, where cytokines can cause intense inflammation and respiratory failure. So the importance of early diagnosis increases, as with the recent pandemic, an anchoring bias can easily lead to misdiagnosing and a delay of treatment. Currently, doxycycline is the standard treatment, but further studies will be required to determine the role of steroids in severe infections, as they may prove beneficial by cooling down the inflammatory cycle. REFERENCE #1: MacQueen D, Centellas F. Human Granulocytic Anaplasmosis. Infect Dis Clin North Am. 2022 Sep;36(3):639-654. doi: 10.1016/j.idc.2022.02.008. PMID: 36116840. REFERENCE #2: Rivera JE, Young K, Kwon TS, McKenzie PA, Grant MA, McBride DA. Anaplasmosis Presenting With Respiratory Symptoms and Pneumonitis. Open Forum Infect Dis. 2020 Jul 4;7(8):ofaa265. doi: 10.1093/ofid/ofaa265. PMID: 32793764; PMCID: PMC7415301. REFERENCE #3: Dahlgren FS, Heitman KN, Drexler NA, Massung RF, Behravesh CB. Human granulocytic anaplasmosis in the United States from 2008 to 2012: a summary of national surveillance data. Am J Trop Med Hyg. 2015 Jul;93(1):66-72. doi: 10.4269/ajtmh.15-0122. Epub 2015 Apr 13. PMID: 25870428; PMCID: PMC4497906. DISCLOSURES: No relevant relationships by Sameer Acharya No relevant relationships by Ali AKRAM No relevant relationships by Mariam Arif No relevant relationships by Sohrab Zand