Skip directly to site content Skip directly to page options Skip directly to A-Z link Skip directly to A-Z link Skip directly to A-Z link

Disclaimer: Early release articles are not considered as final versions. Any changes will be reflected in the online version in the month the article is officially released.

Volume 32, Number 9—September 2026

Research

Improved Case Detection of Fleaborne Typhus by PCR Testing, Los Angeles County, California, USA, 2022–2024

Armine Sanosyan, Zuelma A. Contreras, Van Ngo, Michael K. Brown, Nicole M. Green, Lee A. Borenstein, Jill K. Hacker, Will S. Probert, Alexa C. Quintana, Monica P. Haw, and Umme-Aiman Halai
Author affiliation: Los Angeles County Department of Public Health, Los Angeles, California, USA (A. Sanosyan, Z.A. Contreras, V. Ngo, M.K. Brown, N.M. Green, L.A. Borenstein, U.-A. Halai); California Department of Public Health Center for Laboratory Sciences Viral and Rickettsial Disease Laboratory, Richmond, California, USA (J.K. Hacker, W.S. Probert, A.C. Quintana, M.P. Haw).

Main Article

Table 1

Demographic and clinical characteristics of patients with possible fleaborne typhus, comparing 114 patients with initial low-titer positive serologic results with 289 patients with initial high-titer positive serologic results, Los Angeles County, California, USA, 2022–2024

Characteristics Low-titer positive High-titer positive
Age categories, y
0–17 18 (16) 37 (13)
18–34 31 (27) 56 (19)
35–44 19 (17) 53 (18)
45–54 18 (16) 53 (18)
>55
28 (25)
90 (31)
Median age, y (range)
39 (1–81)
44 (2–87)
Sex
M 60 (53) 177 (61)
F 54 (47) 110 (38)
Other/unknown
0 (0)
2 (0.7)
Race/ethnicity
Hispanic/Latino 69 (61) 178 (62)
White 24 (21) 59 (21)
Asian 6 (5) 22 (8)
Other/unknown
15 (13)
22 (8)
Hospitalized 97 (85) 253 (88)
No. nights hospitalized, median (range)
5 (1–23)
5 (1–83)
Clinical characteristics
Fever 114 (100) 289 (100)
Headache 76 (67) 195 (68)
Muscle pain/myalgia 69 (61) 155 (54)
Nausea/vomiting† 79 (69) 158 (55)
Rash†
57 (50)
93 (32)
Hematology results
Thrombocytopenia, <150,000 platelets/µL† 87 (76) 177 (61)
Elevated ALT or AST, >40 IU/L
105 (96)
280 (98)
Treatment 104 (91) 244 (84)
No. days from specimen collection date to doxycycline treatment initiation, median (range) 0 (–3 to 31) 0 (–15 to 28)
Treated before or on same day of collection date 66 (63) 163 (67)
Treated >1 days after collection date
38 (37)
81 (33)
No. days from symptom onset date to specimen collection date†
<7 41 (36) 50 (17)
8–10 58 (51) 101 (35)
>10 15 (13) 138 (48)
Median (range)† 8 (0–44) 10 (2–65)

*Values are no. (%) except as indicated. †p value <0.05 for this variable indicating significance.

Main Article

Page created: July 17, 2026
Page updated: August 12, 2026
Page reviewed: August 12, 2026
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.
file_external