eMedicine Specialties > Pediatrics: General Medicine > Infectious Disease

Ehrlichiosis: Differential Diagnoses & Workup

Author: Nicholas John Bennett, MB, BCh, PhD, Fellow in Pediatric Infectious Disease, Department of Pediatrics, State University of New York Upstate Medical University
Coauthor(s): Joseph Domachowske, MD, Professor of Pediatrics, Microbiology and Immunology, Department of Pediatrics, Division of Infectious Diseases, State University of New York-Upstate Medical University; Walid Abuhammour, MD, FAAP, Associate Professor of Pediatrics, Michigan State University; Director of Pediatric Infectious Disease, Department of Pediatrics, Hurley Medical Center
Contributor Information and Disclosures

Updated: Jun 2, 2009

Differential Diagnoses

Endocarditis, Bacterial
Meningitis, Bacterial
Henoch-Schoenlein Purpura
Meningococcal Infections
Malaria
Rheumatic Fever
Meningitis, Aseptic
Syphilis

Other Problems to Be Considered

Tick-borne Diseases, Colorado
Relapsing Fever
Acute or chronic gonococcemia
Typhoid fever
Collagen vascular disease
Idiopathic thrombocytopenic purpura
Malaria
Miliary tuberculosis
Erythema multiforme/nodosum
Neoplastic diseases
Haverhill and rat-bite fever (Streptobacillus moniliformis)

Workup

Laboratory Studies

  • Dr E. Dale Everett stated, "The problem is not so much that ehrlichiosis is specifically difficult to diagnose, it is more that some physicians are still unaware of it and thus do not recognize the clinical syndrome."
  • Case definition depends on a positive serologic test or positive polymerase chain reaction (PCR) assay. An alternative may be a single immunofluorescence antibody (IFA) titer of 64 or higher in conjunction with morulae on microscopy (see below).
    • A positive serologic test demonstrates a 4-fold or greater change in antibody titer in blood sera obtained at 4-week intervals following onset of symptoms.
    • Microscopic examination (by an experienced microbiologist) of blood smears stained with eosin-azure type dyes, such as Wright-Giemsa stain, may reveal morulae in the cytoplasm of leukocytes. As many as 20% of patients with human monocytic ehrlichiosis (HME) and 20%-80% of patients with human granulocytic anaplasmosis (HGA) may demonstrate this in the first week of infection. A negative result should not be taken as proof of noninfection.
    • Individual laboratories vary as to their specific positive criteria for indirect IFA testing. A probable infection is one with an IFA titer of 64 or higher or morulae on microscopy. Some laboratories are able to perform an enzyme-linked immunoassay (ELISA).
    • The Centers for Disease Control and Prevention (CDC), certain state health laboratories, and a limited number of research and commercial laboratories offer the PCR test. A peripheral blood test is sufficient to perform this because these pathogens infect circulating lymphocytes.
    • Abnormal liver enzymes are found in 86% of patients.
    • Leukopenia is found in 60% of patients.
    • Thrombocytopenia is found in 68% of patients.
    • Abnormal cerebrospinal fluid also can be observed.
    • Hyponatremia (<130 mEq/L) is found in 40% of patients.
    • Elevated C-reactive protein (CRP) levels are common in the first week of illness and typically resolve by the end of the second week.

Imaging Studies

  • An abnormal chest radiograph is observed in 50% of patients with ehrlichiosis and respiratory symptoms.

Histologic Findings

  • Buffy coat examination may reveal intracytoplasmic inclusions (morulae), which are characteristic of ehrlichiosis.
  • Morulae are observed in the cytoplasm of neutrophils in patients with HGA and in mononuclear cells in patients with HME. Only a minority of patients with HME have detectable morulae.

More on Ehrlichiosis

Overview: Ehrlichiosis
Differential Diagnoses & Workup: Ehrlichiosis
Treatment & Medication: Ehrlichiosis
Follow-up: Ehrlichiosis
Multimedia: Ehrlichiosis
References
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References

  1. Schneider JG. Human ehrlichiosis: a case study. Clin Lab Sci. Winter 2009;22(1):3-8. [Medline].

  2. Ganguly S, Mukhopadhayay SK. Tick-borne ehrlichiosis infection in human beings. J Vector Borne Dis. Dec 2008;45(4):273-80. [Medline].

  3. Buller RS, Arens M, Hmiel SP, et al. Ehrlichia ewingii, a newly recognized agent of human ehrlichiosis. N Engl J Med. Jul 15 1999;341(3):148-55. [Medline].

  4. Anaplasma phagocytophilum transmitted through blood transfusion--Minnesota, 2007. MMWR Morb Mortal Wkly Rep. Oct 24 2008;57(42):1145-8. [Medline].

  5. McQuiston JH, Paddock CD, Holman RC, Childs JE. The human ehrlichioses in the United States. Emerg Infect Dis. Sep-Oct 1999;5(5):635-42. [Medline].

  6. Demma LJ, Holman RC, McQuiston JH, Krebs JW, Swerdlow DL. Human monocytic ehrlichiosis and human granulocytic anaplasmosis in the United States, 2001-2002. Ann N Y Acad Sci. Oct 2006;1078:118-9. [Medline].

  7. [Guideline] Chapman AS, Bakken JS, Folk SM, et al. Diagnosis and management of tickborne rickettsial diseases: Rocky Mountain spotted fever, ehrlichioses, and anaplasmosis--United States: a practical guide for physicians and other health-care and public health professionals. MMWR Recomm Rep. Mar 31 2006;55(RR-4):1-27. [Medline]. [Full Text].

  8. Bakken JS, Krueth J, Wilson-Nordskog C, et al. Clinical and laboratory characteristics of human granulocytic ehrlichiosis. JAMA. Jan 17 1996;275(3):199-205. [Medline].

  9. Committee on Infectious Diseases. Ehrlichiosis. In: Red Book. 2006:281-4.

  10. Dumler JS, Barbet AF, Bekker CP, et al. Reorganization of genera in the families Rickettsiaceae and Anaplasmataceae in the order Rickettsiales: unification of some species of Ehrlichia with Anaplasma, Cowdria with Ehrlichia and Ehrlichia with Neorickettsia, descriptions of six new species combinations and designation of Ehrlichia equi and 'HGE agent' as subjective synonyms of Ehrlichia phagocytophila. Int J Syst Evol Microbiol. Nov 2001;51(Pt 6):2145-65. [Medline].

  11. Dumler JS, Choi KS, Garcia-Garcia JC, et al. Human granulocytic anaplasmosis and Anaplasma phagocytophilum. Emerg Infect Dis. Dec 2005;11(12):1828-34. [Medline].

  12. Glushko GM. Human ehrlichiosis. Postgrad Med. Jun 1997;101(6):225-30. [Medline].

  13. Jacobs RF, Schutze GE. Ehrlichiosis in children. J Pediatr. Aug 1997;131(2):184-92. [Medline].

  14. Laudicina RJ, Hilger AE. Human ehrlichiosis: a case review. Clin Lab Sci. 1997;10(3):149-66.

  15. Ogden NH, Woldehiwet Z, Hart CA. Granulocytic ehrlichiosis: an emerging or rediscovered tick-borne disease?. J Med Microbiol. Jun 1998;47(6):475-82. [Medline].

  16. Schaffner W, Standaert SM. Ehrlichiosis--in pursuit of an emerging infection. N Engl J Med. Jan 25 1996;334(4):262-3. [Medline].

  17. Wormser GP, Dattwyler RJ, Shapiro ED, et al. The clinical assessment, treatment, and prevention of lyme disease, human granulocytic anaplasmosis, and babesiosis: clinical practice guidelines by the Infectious Diseases Society of America. Clin Infect Dis. Nov 1 2006;43(9):1089-134. [Medline]. [Full Text].

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Further Reading

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Keywords

ehrlichiosis, human monocytic ehrlichiosis, HME, human granulocytic ehrlichiosis, HGE, human granulocytic anaplasmosis, HGA, tick-borne disease, Rickettsiae, Ehrlicia, Anaplasma, anaplasmosis, coccobacilli, Ehrlichia chaffeensis, Anaplasma phagocytophilum, human monocytic ehrlichiosis, HME, human granulocytic anaplasmosis, HGA, human granulocytic ehrlichiosis, HGE, Lyme disease, Ehrlichia phagocytophilum, Ehrlichia equi, Ehrlichia ewingii, Amblyomma americanum, Ixodes scapularis, Ixodes pacificus, Ixodes ricinus, Ixodes persulcatus, Rocky Mountain spotted fever, myalgia, arthralgia, malaise, photophobia

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Contributor Information and Disclosures

Author

Nicholas John Bennett, MB, BCh, PhD, Fellow in Pediatric Infectious Disease, Department of Pediatrics, State University of New York Upstate Medical University
Nicholas John Bennett, MB, BCh, PhD is a member of the following medical societies: Alpha Omega Alpha and American Academy of Pediatrics
Disclosure: Nothing to disclose.

Coauthor(s)

Joseph Domachowske, MD, Professor of Pediatrics, Microbiology and Immunology, Department of Pediatrics, Division of Infectious Diseases, State University of New York-Upstate Medical University
Joseph Domachowske, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Pediatrics, American Society for Microbiology, Infectious Diseases Society of America, Pediatric Infectious Diseases Society, and Phi Beta Kappa
Disclosure: Nothing to disclose.

Walid Abuhammour, MD, FAAP, Associate Professor of Pediatrics, Michigan State University; Director of Pediatric Infectious Disease, Department of Pediatrics, Hurley Medical Center
Walid Abuhammour, MD, FAAP is a member of the following medical societies: American Medical Association and Pediatric Infectious Diseases Society
Disclosure: Nothing to disclose.

Medical Editor

Michael D Nissen, MBBS, BMedSc, FRACP, FRCPA, Associate Professor in Biomolecular, Biomedical Science & Health, Griffith University; Director of Infectious Diseases and Unit Head of Queensland Paediatric Infectious Laboratory, Sir Albert Sakzewski Viral Research Centre, Royal Children's Hospital
Michael D Nissen, MBBS, BMedSc, FRACP, FRCPA is a member of the following medical societies: American Academy of Pediatrics, American Society for Microbiology, Pediatric Infectious Diseases Society, Royal Australasian College of Physicians, and Royal College of Pathologists of Australasia
Disclosure: Nothing to disclose.

Pharmacy Editor

Mary L Windle, PharmD, Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy, Pharmacy Editor, eMedicine
Disclosure: Pfizer Inc Stock Investment from financial planner; Avanir Pharma Stock Investment from financial planner ; WebMD Salary and stock Employment and investment from financial planner

Managing Editor

Joseph Domachowske, MD, Professor of Pediatrics, Microbiology and Immunology, Department of Pediatrics, Division of Infectious Diseases, State University of New York-Upstate Medical University
Joseph Domachowske, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Pediatrics, American Society for Microbiology, Infectious Diseases Society of America, Pediatric Infectious Diseases Society, and Phi Beta Kappa
Disclosure: Nothing to disclose.

CME Editor

Robert W Tolan Jr, MD, Chief, Division of Allergy, Immunology and Infectious Diseases, The Children's Hospital at Saint Peter's University Hospital; Clinical Associate Professor of Pediatrics, Drexel University College of Medicine
Robert W Tolan Jr, MD is a member of the following medical societies: American Academy of Pediatrics, American Medical Association, American Society for Microbiology, American Society of Tropical Medicine and Hygiene, Infectious Diseases Society of America, Pediatric Infectious Diseases Society, Phi Beta Kappa, and Physicians for Social Responsibility
Disclosure: GlaxoSmithKline Honoraria Speaking and teaching; MedImmune Honoraria Speaking and teaching; Merck Honoraria Speaking and teaching; sanofi pasteur Honoraria Speaking and teaching; Baxter Healthcare Honoraria Speaking and teaching

Chief Editor

Russell W Steele, MD, Head, Division of Pediatric Infectious Diseases, Ochsner Children's Health Center; Clinical Professor, Department of Pediatrics, Tulane University School of Medicine
Russell W Steele, MD is a member of the following medical societies: American Academy of Pediatrics, American Association of Immunologists, American Pediatric Society, American Society for Microbiology, Infectious Diseases Society of America, Louisiana State Medical Society, Pediatric Infectious Diseases Society, Society for Pediatric Research, and Southern Medical Association
Disclosure: None None None

 
 
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