B52-12 Murine Typhus-associated Cardiomyopathy: A Rare Cause of Reversible Heart Failure in Severe Systemic Illness

Abstract Introduction Murine (also known as ‘endemic’ or ‘flea-borne’) typhus is a rickettsial disease caused by the gram-negative, obligately intracellular coccobacillus Rickettsia typhi. In this case report, we highlight a patient who presented with sepsis and cardiomyopathy secondary to murine typhus who was subsequently treated using targeted antibiotics and guideline directed medical therapy for heart failure. Case description A 37-year-old previously healthy female presented with a one-week history of recurrent fevers, persistent cough, and progressive dyspnea. On admission, she was septic and in acute hypoxic respiratory failure. Initial laboratory evaluation revealed hyponatremia (Na + 131 mmol/L), transaminitis (AST 190 U/L, ALT 228 U/L), and thrombocytopenia (55 × 10³/µL). Chest radiography demonstrated bilateral interstitial and bibasilar opacities with blunting of the costophrenic angles. Empiric therapy for community-acquired pneumonia was initiated, along with doxycycline due to clinical suspicion for Rickettsia typhi infection. Transthoracic echocardiography showed a reduced left ventricular ejection fraction (LVEF) of 46% with diffuse left ventricular hypokinesis. The differential diagnosis for new-onset heart failure with reduced ejection fraction included R. typhi myocarditis, stress-induced cardiomyopathy, or a multifactorial etiology. Rickettsial serologies subsequently returned positive for R. typhi (IgM 1:1024). Antibiotics were narrowed to doxycycline, resulting in marked improvement in the patient’s respiratory status, laboratory abnormalities, and overall clinical condition. Prior to discharge, guideline-directed medical therapy for heart failure (sacubitril/valsartan and carvedilol) was initiated. At follow-up, the patient’s symptoms had completely resolved, and repeat transthoracic echocardiography demonstrated normalization of her left ventricular systolic function (LVEF 54%) and no regional wall motion abnormalities. Discussion In recent years, the incidence of murine typhus has increased in the United States, particularly in southern Texas and California. Multiple reports have been published highlighting severe and sometimes fatal cases due to multi-organ dysfunction, including neurologic and cardiac involvement. Initial clinical presentations can be nonspecific, most commonly manifesting as an acute febrile illness with associated signs and symptoms, including headaches, chills, malaise, myalgias, anorexia, and a macular or maculopapular rash, often located on the trunk. Given the lack of rapid confirmatory diagnostic testing and the potential for progression to fulminant disease, empiric treatment with doxycycline should be initiated promptly when murine typhus is suspected. Delayed treatment is associated with increased morbidity and mortality. This case highlights murine typhus as a rare cause of reversible cardiomyopathy and underscores the importance of early recognition and targeted therapy in patients presenting with severe systemic illness and cardiac involvement. This abstract is funded by: None