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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 3

PCR results by timing of specimen collection and serologic findings of 103 specimens from patients with suspected Rickettsia typhi infection, Los Angeles County, California, USA, 2022–2024*

Characteristics PCR positive, n = 81 PCR negative, n = 22
No. days from symptom onset date to specimen collection date†
<7 34 (42) 4 (18)
8–10 40 (49) 11 (50)
>10 7 (9) 7 (32)
Median (range)†
 8 (1–15)
 9 (0–44)
Time from specimen collection date to doxycycline treatment start
Treated before or on same day of collection 49 (64) 11 (65)
Treated >1 days after collection date
 28 (36)
 6 (35)
Initial commercial laboratory R. typhi IgG titer†
<1:64 48 (59) 7 (32)
1:64
 33 (41)
 15 (68)
Initial commercial laboratory R. typhi IgM titer†
<1:64 6 (7) 12 (55)
1:64 51 (63) 8 (36)
1:128
 24 (30)
 2 (9)
Initial commercial laboratory R. typhi results†
IgM detected at 1:64 or 1:128 titer, IgG not detected 48 (59) 7 (32)
IgM not detected, IgG detected at 1:64 titer 6 (7) 12 (55)
IgM and IgG detected 27 (33) 3 (14)

*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.
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