52-Lone Star Tick Bites Big Apple: Ehrlichia chaffeensis-Induced Hemophagocytic Lymphohistiocytosis
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Immunology, Pediatrics, 2021
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The Society of Critical Care Medicine's Critical Care Congress features internationally renowned faculty and content sessions highlighting the most up-to-date, evidence-based developments in critical care medicine. This is a presentation from the 2021 Critical Care Congress held virtually from January 31-February 12, 2021.

Shashikanth Reddy Ambati, MD


Introduction: Hemophagocytic lymphohistiocytosis (HLH) is a group of disorders of the mononuclear phagocyte system in which there is uncontrolled activation of the cellular immune system. While HLH is a rare disorder it can be a life-threatening condition with an overall mortality of 58-75%. HLH disease can be due to genetic defects but can also be triggered by infections, of which Ehrlichia is one rare cause. E.Chaffeensis is transmitted to humans through an infected lone star tick. Here we describe a case of HLH induced by Ehrlichia.

Description: A 9-year-old male presented with two-day history of rash and fever. He was visiting New York from his home in rural Tennessee and was previously healthy, except with a recent abrasion on his thigh with localized cellulitis being treated with trimethoprim-sulfamethoxazole (TMP-SMX). A week after starting TMP-SMX, he developed a full body macular rash and subsequently fever and hepatosplenomegaly. His blood tests showed leukopenia, anemia, thrombocytopenia, and transaminitis. His coagulation studies were also abnormal, ferritin was elevated to >50,000 and fibrinogen was low. Based on the above clinical and laboratory data, HLH was diagnosed. He was started on high dose dexamethasone. On Day 2 of hospitalization, E. chaffeensis was detected by PCR and doxycycline was started. His fever and rash improved by Day 3 of doxycycline and steroids and his ferritin significantly decreased. His overall clinical status improved, and laboratory studies ultimately returned to normal. He was discharged with doxycycline to complete a total 2-week course with tapering steroids.

Discussion: Drug induced rash from TMP-SMX was the initial impression in our patient. There was no known history of recent tick bites, however, his history of living in a rural part of Tennessee led us to test for tick borne diseases. HLH is typically due to pathological immune activation due to genetic defects but secondary causes such as infections must be ruled out. Due to the high mortality associated with HLH, this case highlights the importance of recognizing and evaluating for potential infectious causes when encountered with HLH. The prognosis of Ehrlichia induced HLH is excellent if diagnosed early with prompt initiation of treatment.


Meta Tag
Content Type Presentation
Knowledge Area Immunology
Knowledge Area Pediatrics
Knowledge Level Advanced
Membership Level Select
Tag Infectious Diseases
Year 2021
hemophagocytic lymphohistiocytosis
ehrlichia chafensis
tick-borne pathogen
genetic analysis


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