S3643 Rocky Mountain Spotted Fever Masquerading as Gastroenteritis

Abstract

Introduction: Rocky Mountain spotted fever (RMSF) is a potentially lethal tick-borne illness. RMSF multiplies within blood vessels, causing endothelial damage before spreading hematologically to affect various organ. The classic triad of fever, rash, and a recent tick bite is rarely present at diagnosis. Less known, but more common initial presentations include hepatic and gastrointestinal (GI) symptoms such as anorexia, nausea, vomiting, abdominal pain, and elevated liver function tests (LFT’s). We present a case of RMSF that demonstrates the diagnostic challenges associated with this illness. Case Description/Methods: A 20-year-old male presented to the hospital with diarrhea and abdominal pain. He was tachycardic and febrile to 104oF. Blood work was remarkable for elevated LFT’s (AST 240 U/L, ALT 247 U/L, Tb 7.2 mg/dL and ALP 451 U/L). Abdominal computed tomography revealed ascites, periportal edema, and splenomegaly with infarction. The patient was empirically placed on piperacillin-tazobactam. Chronic liver disease and infectious disease work ups were unmemarkable. Over the next three days, his symptoms worsened and he had increasing leukocytosis and LFT’s. A liver biopsy was obtained revealing portal-based inflammation consisting predominantly of neutrophils, and mild bile ductular proliferation (Figure). On the fourth day, a serologic test for RMSF IgM antibodies was positive. The patient’s antibiotics were changed to doxycycline. One day after the antibiotic change his fever resolved, LFT’s decreased and GI symptoms improved. Discussion: RMSF is an uncommon disease that remains a diagnostic challenge for physicians. GI symptoms are the more prominent features in up to 80% of RMSF patients and often precedes the appearance of a rash. Liver involvement in RMSF is also common, most frequently manifesting as AST and ALT elevation, with jaundice being a poor prognostic factor. Liver biopsies reveal infection of the endothelial lining and periportal inflammation. The treatment of choice for RMSF is doxycycline and patients often experience rapid improvement within 72 hours. Delayed treatment can lead to fulminant disease with a mortality rate of 25%, thus prompt diagnosis and early administration of appropriate antibiotics is imperative. Clinicians should be educated about the early manifestation of RMSF and consider it among the differential diagnoses in a patient with fever, GI symptoms, and hepatic involvement.Figure 1.: Liver biopsy in Rocky Mountain spotted fever revealing a nonspecific reactive hepatitis with peri-portal inflammation and surrounding bile ductular inflammation and proliferation.