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Volume 21, Number 10—October 2015

Human Infection with Ehrlichia muris–like Pathogen, United States, 2007–20131

Diep K. Hoang Johnson2, Elizabeth Schiffman2, Jeffrey P. Davis, David Neitzel, Lynne M. Sloan, William L. Nicholson, Thomas R. Fritsche, Christopher R. Steward, Julie A. Ray, Tracy K. Miller, Michelle A. Feist, Timothy S. Uphoff, Joni J. Franson, Amy L. Livermore, Alecia K. Deedon, Elitza S. Theel, and Bobbi PrittComments to Author 
Author affiliations: Wisconsin Department of Health Services, Madison, Wisconsin, USA (D.K. Hoang Johnson, J.P. Davis, C.R. Steward, A.K. Deedon); Minnesota Department of Health, St. Paul, Minnesota, USA (E.K. Schiffman, D.F. Neitzel, J.A. Ray); Mayo Clinic, Rochester, Minnesota, USA (L.M. Sloan, E.S. Theel, B.S. Pritt); Centers for Disease Control and Prevention, Atlanta, Georgia, USA (W.L. Nicholson); Marshfield Clinic, Marshfield, Wisconsin, USA (T.R. Fritsche, T.S. Uphoff); North Dakota Department of Health, Bismarck, North Dakota, USA (T.K. Miller, M.A. Feist); Mayo Clinic Health System, Eau Claire, Wisconsin, USA (J.J. Franson); Mayo Medical Laboratories, Andover, Massachusetts, USA (A.L. Livermore).

Main Article

Table 2

Clinical features and laboratory findings among patients infected with the EML pathogen, United States, 2007–2013*

Clinical features
Patient age at illness onset, y
Range 15–94
Mean 60.8
M 44/69 (64%)
25/69 (36%)
Period from symptom onset to testing, d
Range 0–145
Mean 9.5
Immunocompromised state† 13/49 (27%)
Solid organ allograft recipient 7
Receipt of chemotherapy for malignancy 2
Receipt of systemic steroids for autoimmune disease‡
Patient symptoms†
Fever 60/69 (87%)
Malaise/fatigue 47/62 (76%)
Headache 46/69 (67%)
Myalgia 41/68 (60%)
Nausea/vomiting 15/69 (22%)
8/69 (12%)
Laboratory findings†§
Anemia 18/50 (36%)
Leukopenia 20/51 (39%)
Lymphopenia 17/32 (53%)
Thrombocytopenia 34/51 (67%)
Elevated AST or ALT 18/23 (78%)
Ehrlichia chaffeensis positive serology, acute 1/6 (17%)
Anaplasma phagocytophilum positive serology, acute 1/6 (17%)
Borrelia burgdorferi positive serology or PCR
2/28 (7%)
Doxycycline treatment†¶ 66/68 (96%)
Length of treatment, d
Range 7–30
Mean 15.0
Hospitalization†# 16/69 (23%)
Length of stay, d
Range 2–15
Mean 6.1
Immunocompromised patients† 10/15 (67%)
Death† 0/69 (0%)

*ALT, alanine aminotransferase; AST, aspartate aminotransferase; EML, Ehrlichia muris–like.
†Expressed as number of patients with a specific risk factor, symptom, laboratory finding, or outcome, divided by the number of patients with available data. Corresponding percentage is also provided.
‡Of the 4 patients receiving systemic steroids for an autoimmune condition, 3 had rheumatoid arthritis, and 1 had mixed connective tissue disease.
§Anemia, hemoglobin <13.5g/dL for male or <12.0g/dL for female patients; leukopenia, <3.5 cells x 10−9/liter; thrombocytopenia, <150 cells × 10−9/liter; elevated AST, >48 U/liter; elevated ALT, >55 U/liter; positive Ehrlichia chaffeensis or Anaplasma phagocytophilum serology, reciprocal IgG titer >64.
¶Two patients recovered without treatment. Treatment information was unavailable for 1 patient.
#Length of stay was unknown for 2 of the 16 hospitalized patients.

Main Article

1Preliminary data from this study were presented at the American Society for Clinical Laboratory Science–Minnesota meeting, March 8, 2012, St. Cloud, Minnesota, USA; the Interscience Conference of Antimicrobial Pathogens and Chemotherapy, September 9–12, 2012, San Francisco, California, USA; the Emerging Infections in Clinical Practice and Public Health Continuing Medical Education Conference, November 16, 2012, Minneapolis, Minnesota, USA; the Interscience Conference of Antimicrobial Pathogens and Chemotherapy, September 10–13, 2013, Washington, DC, USA; the Entomological Society of America annual meeting, November 10–13, 2013, Austin, Texas, USA; the American Society of Tropical Medicine and Hygiene annual meeting, November 13–17, 2013, Washington, DC, USA; the European Congress of Clinical Microbiology and Infectious Diseases, May 10–13, 2014, Barcelona, Spain; and the International Conference on Diseases in Nature Communicable to Man, August 10–12, 2014, Vancouver, British Columbia, Canada.

2These authors contributed equally to this article.

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Page updated: September 22, 2015
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