P0462 - Don’t Forget to Ask About Ticks: An Unusual Clinical Course of Ehrlichiosis in a Teenage Boy

Introduction: This case demonstrates a severe clinical course, including septic shock and an HLH-like syndrome, of a teenager who presented with febrile illness and was ultimately diagnosed with Ehrlichiosis.

Case Description: A 16 y/o male was admitted to our facility with a 5-day h/o vomiting, fatigue, nonspecific abdominal pain and fever. He reported a recent 15lb weight loss and tick bites on his left ankle. On admission, he was febrile to 39.4°C and moderately tachycardic. He had a petechial rash on his back and lower extremities, and a maculopapular rash on his abdomen. He was leukopenic (3.2), thrombocytopenic (63), borderline hyponatremic (135), and had elevated LFTs (AST 125, ALT 107). Doxycycline was started initially, but soon he developed florid shock and flushing, so vancomycin and clindamycin were added to cover for Toxic Shock Syndrome. The patient developed a right-sided pleural effusion and required chest tube placement and escalation of his respiratory support to high flow nasal cannula. Further workup revealed anemia (11.1), hypoalbuminemia (2.6), elevated ferritin (6161), hypertriglyceridemia (328) and splenomegaly. We also tested him for Rickettsia, EBV, CMV, Ehrlichia, and HIV. Due to the above clinical findings, there was strong suspicion for HLH. However, the patient only met 4 out of 5 diagnostic criteria [1]. Of note, BM biopsy and NK cell testing were not performed. The patient gradually improved over the first week of admission. The patient tested positive for Ehrlichia DNA but negative for Ehrlichia antibody, consistent with acute infection. Hematology was consulted, and agreed with a likely diagnosis of HLH-like syndrome although the patient never fully met diagnostic criteria. Patient was discharged home on day 12 of admission.

Discussion: Ehrlichiosis is a tick-borne disease that presents as an acute febrile illness with headache, myalgias, and a nonspecific rash [2]. Leukopenia and hyponatremia are common laboratory abnormalities. Doxycycline is the treatment of choice. Although Ehrlichiosis can have a mild presentation, it can progress to severe sepsis that is unresponsive to conventional antibiotics. Ehrlichiosis is a rare cause of HLH, a disease that primarily affects macrophages and T-lymphocytes resulting in excessive production of inflammatory cytokines that can cause irreversible tissue damage and multi-organ failure [1]. A literature review of the past 5 years revealed 3 case reports of pediatric patients who developed HLH due to Ehrlichiosis infection [3, 4, 5]. HLH should be considered in severe cases of Ehrlichiosis. Due to these possible complications, prompt empiric treatment with doxycycline while awaiting test results is crucial.

Conclusion: Ehrlichiosis is an increasingly common disease that may present with septic shock and HLH. Appropriate provider knowledge of the disease, and thus prompt diagnosis and treatment, is essential.