Case Presentation: 68-year-old man presented during summer with two weeks of weakness and shortness of breath. He had associated chills, myalgia, arthralgia, blurry vision, dry mouth, dizziness, dry cough, and dysuria. On initial presentation, he had new-onset atrial fibrillation (AFib) with rapid ventricular response and hypotension prompting admission to intensive care. After treatment with amiodarone and metoprolol he converted to normal sinus rhythm and was started on apixaban. He was transferred to Medicine service and continued to have fatigue, myalgia, weakness, dry mouth, and fevers. He had extensive animal exposure including two dogs, one cat, and a parrot at home. He lived in Texas by the bayou, known to have a lot of rats. He noted fleas on himself in the past. On exam, he appeared ill and fatigued with significant shortness of breath. Conjunctiva were slightly injected, there was marked xerostomia, and cervical lymphadenopathy. His pulse was normal rate and regular rhythm. There were normal heart sounds without murmurs. Slight bibasilar crackles heard on lung auscultation. There was vague abdominal tenderness. His skin appeared mottled. Labs were notable for thrombocytopenia, leukocytosis with neutrophilic predominance and left shift, elevated procalcitonin, hyponatremia, hyperbilirubinemia, elevated liver enzymes, and elevated lactate dehydrogenase. Peripheral smear had atypical lymphocytes without bacterial or fungal inclusions. Tests for influenza, RSV, HIV, Bartonella, mononucleosis, Cryptococcus, Legionella, viral hepatitis, and Histoplasmosis were negative. Blood, urine, and sputum cultures were negative. Thyroid function tests were normal. Chest X-ray revealed mild interstitial edema and computed tomography showed airspace and nodular opacities in the lung bases. He was empirically started on doxycycline given concern for zoonotic bacterial infection. He continued to feel poorly and had worsening hepatocellular injury for two more days, after which he started to improve significantly. Eventually typhus IgM and IgG antibodies resulted strongly positive. On discharge, he felt markedly better, and all labs were improving. He has paroxysmal AFib that had not returned at follow-up and is presumably the result of murine typhus.
Discussion: Murine typhus is a febrile illness caused by Rickettsia typhi, transmitted by fleas (most commonly from rats). In temperate regions, the disease is most common during hot, dry periods. It can be misdiagnosed due to nonspecific symptoms. The classic triad is fever, rash, and headache; observed in 33-59% of cases. The syndrome of a febrile illness with a prominence of headache and skin changes, thrombocytopenia, and liver injury should prompt concern for zoonotic bacterial infection including rickettsia or similar intracellular bacteria (e.g. rocky mountain spotted fever, ehrlichiosis, murine typhus, leptospirosis, etc). Many patients may not remember a fleabite or contact with rodents. Empiric treatment with tetracycline-containing regimen is recommended for patients in whom a diagnosis of murine typhus is suspected.
Conclusions: Murine typhus can be difficult to diagnosis due to presentation of nonspecific symptoms. A thorough history and physical is salient to recognize Rickettsial disease. Murine typhus is transmitted by fleas of rats, cats, and opossums with most cases reported in Texas, California, and Hawaii. While disease is often mild, complications can be severe and treatment with doxycycline significantly decreases duration.