Case Report

Ehrlichiosis: Making the Diagnosis in the Acute Setting

Authors: Lisa K. Prince, MD, Anita A. Shah, DO, Luis J. Martinez, MD, Kimberly A. Moran, MD


Human monocytic ehrlichiosis (HME) is a tick-borne disease transmitted during the summer months in the mid-Atlantic, southeastern and south-central United States. A large proportion of patients presenting with ehrlichiosis must be hospitalized because of the severity of their presenting signs, symptoms and lab abnormalities. We report a case of HME presenting with negative serologies and positive DNA PCR for Ehrlichia chaffeensis during the acute illness. The patient was empirically treated with doxycycline before the availability of diagnostic test results and had a rapid recovery. This report summarizes the common findings of ehrlichiosis on presentation, diagnostic strategies, and treatment options. This case emphasizes the importance of considering tick-borne diseases in the differential diagnosis for patients presenting with nonspecific febrile syndromes in endemic areas and using the clinical scenario to determine whether empiric treatment for a tick-borne disease is necessary. Delaying treatment while awaiting confirmatory tests is unnecessary, and may result in a less favorable patient outcome.

Key Points

* Serology for human monocytic ehrlichiosis may not be positive during the acute phase of the infection.

* PCR is a useful diagnostic tool in early Ehrlichia chaffeensis infection.

* Treatment for ehrlichiosis should not be delayed while awaiting confirmatory lab tests.

* Doxycycline is both diagnostic and therapeutic in cases of ehrlichiosis.

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1. Maeda K, Markowitz N, Hawley RC, et al. Human infection with Ehrlichia canis, a leukocytic rickettsia. N Engl J Med 1987;316:853–856.
2. Chapman AS, Bakken JS, Fold SM, et al. Diagnosis and management of tickborne rickettsial diseases: Rocky Mountain spotted fever, ehrlichiosis, and anaplasmosis—United States: a practical guide for physicians and other health-care and public health professionals. MMWR Recommendations and Reports 2006:55 (RR04);1–27.
3. Demma LJ, Holman RC, McQuiston JH, et al. Epidemiology of human ehrlichiosis and anaplasmosis in the United States, 2001–2002. Am J Trop Med Hyg 2005;73:400–409.
4. Paddock CD, Childs JE. Ehrlichia chaffeensis: a prototypical emerging pathogen. Clin Microbiol Rev2003;16:37–64.
5. Olano JP, Walker DH. Human ehrlichiosis. Med Clin North Am 2002;86:375–392.
6. Olano JP, Hogrefe W, Seaton B, et al. Clinical manifestations, epidemiology, and laboratory diagnosis of human monocytotropic ehrlichiosis in a commercial laboratory setting. Clin Diagn Lab Immunol 2003;10:891–896.
7. Hamilton KS, Stanaert SM, Kinney MC. Characteristic peripheral blood findings in human ehrlichiosis. Mod Pathol 2004;17:512–517.
8. Stone JH, Dierberg K, Aram G, et al. Human monocytic ehrlichiosis. JAMA 2004;292:2263–2270.