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Volume 29, Number 9—September 2023
CME ACTIVITY - Synopsis

Characteristics of Hard Tick Relapsing Fever Caused by Borrelia miyamotoi, United States, 2013–2019

David W. McCormick, Catherine M. Brown, Jenna Bjork, Kim Cervantes, Brenda Esponda-Morrison, Jason Garrett, Natalie Kwit, Abigail Mathewson, Charles McGinnis, Marco Notarangelo, Rebecca Osborn, Elizabeth Schiffman, Haris Sohail, Amy M. Schwartz, Alison F. Hinckley, and Kiersten J. KugelerComments to Author 
Author affiliations: Centers for Disease Control and Prevention, Fort Collins, Colorado, USA (D.W. McCormick, A.M. Schwartz, A.F. Hinckley, K.J. Kugeler); Massachusetts Department of Public Health, Boston, Massachusetts, USA (C.M. Brown); Minnesota Department of Health, Minneapolis, Minnesota, USA (J. Bjork, E. Schiffman); New Jersey Department of Health, Trenton, New Jersey, USA (K. Cervantes); Connecticut Department of Public Health, Hartford, Connecticut, USA (B. Esponda-Morrison); Rhode Island Department of Health, Providence, Rhode Island, USA (J. Garrett, C. McGinnis); Vermont Department of Health, Burlington, Vermont, USA (N. Kwit); New Hampshire Department of Health and Human Services, Concord, New Hampshire, USA (A. Mathewson, M. Notarangelo); Wisconsin Department of Health Services, Madison, Wisconsin, USA (R. Osborn); Maine Center for Disease Control and Prevention, Augusta, Maine, USA (H. Sohail)

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Table 2

Clinical and laboratory findings for persons who have confirmed and possible hard tick relapsing fever caused by Borrelia miyamotoi identified by public health surveillance, United States, 2013–2019*

Characteristic Confirmed, n = 165 Possible, n = 133 p value
Hospitalized
 20 (12)
 19 (14)
 0.61
Median duration of illness, d† (IQR)
 3 (2–7)
 9 (3–29)
 0.03
Required symptoms
Fever 157 (95) 108 (81) <0.0001
Chills
 115 (70)
 87 (65)
 0.27
Supporting signs and symptoms
Headache 118 (72) 96 (72) 0.85
Myalgia 104 (63) 94 (71) 0.20
Arthralgia 79 (48) 84 (63) 0.02
Malaise/fatigue 125 (76) 99 (74) 0.55
Rash 21 (13) 28 (21) 0.06
Abdominal pain 16 (10) 27 (20) 0.01
Nausea 55 (33) 36 (27) 0.26
Vomiting 23 (14) 15 (11) 0.44
Diarrhea 8 (5) 17 (13) 0.01
Dizziness 26 (16) 33 (25) 0.06
Confusion 7 (4) 24 (18) <0.0001
Photophobia 8 (5) 11 (8) 0.29
Leukopenia‡ 31 (46) 8 (22) 0.02
Thrombocytopenia§ 40 (58) 9 (25) 0.001
Increased levels of aminotransferases¶
 27 (45)
 13 (36)
 0.41
Other symptoms
Recurring fevers 37 (22) 47 (35) 0.01
Shortness of breath 5 (3) 14 (11) 0.01
Cough 15 (9) 10 (8) 0.53
Anorexia 32 (19) 26 (20) 0.99
Jaundice 2 (1) 4 (3) 0.21
Lymphadenopathy 0 (0) 0 (0) NA
Cognitive impairment/mood disturbance 7 (4) 21 (16) 0.0004
Meningitis/encephalitis 0 (0) 5 (4) 0.01
Neutropenia 6 (4) 2 (2) 0.11
Abnormal chest radiograph 11 (7) 2 (2) 0.04

*Values are no. (%) unless indicated otherwise. IQR, interquartile range; NA, not available. †Defined as duration from symptom onset to first seeking medical care. ‡Information regarding a patient’s leukocyte count was available for 68 confirmed and 37 possible cases. §Information regarding a patient’s platelet count was available for 69 confirmed and 36 possible cases. ¶Information regarding a patient’s alanine and aspartate aminotransferase levels was available for 60 confirmed and 36 possible cases.

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Page created: July 06, 2023
Page updated: August 18, 2023
Page reviewed: August 18, 2023
The conclusions, findings, and opinions expressed by authors contributing to this journal do not necessarily reflect the official position of the U.S. Department of Health and Human Services, the Public Health Service, the Centers for Disease Control and Prevention, or the authors' affiliated institutions. Use of trade names is for identification only and does not imply endorsement by any of the groups named above.
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