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 31, Number 11—November 2025

Research Letter

Orientia tsutsugamushi Antibodies in Patients with Eschars and Suspected Tickborne Disease

Haley A. Abernathy1, Lauryn Ursery1, Brooke A. Merdjane, Dana A. Giandomenico, and Ross M. BoyceComments to Author 
Author affiliation: Author affiliation: University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA

Main Article

Table 1

Seropositivity estimates based on IgM and IgG ELISA at varying optical density thresholds in study of Orientia tsutsugamushi bacteria in patients with eschars and suspected tickborne disease, North Carolina, USA, 2020–2022*

Test Optical density cutoff Sensitivity Specificity Positive, n = 92 % Seropositive (95% CI)
IgG ELISA 0.37 NR NR 8 8.7 (3.8–16.4)
IgG ELISA (8) 1.0 97.5 60 1 1.1 (0.0–5.9)
IgG ELISA (8) 1.6 91 75 0 0.0 (0.0–3.9)
IgM ELISA (8,9) 0.6 96.4 82.7 2 2.2 (0.3–7.6)
IgM ELISA (8) 0.492 97.1 79.1 4 4.3 (1.2–10.8)

*NR, not reported.

Main Article

References
  1. Rajapakse  S, Weeratunga  P, Sivayoganathan  S, Fernando  SD. Clinical manifestations of scrub typhus. Trans R Soc Trop Med Hyg. 2017;111:43–54. DOIPubMedGoogle Scholar
  2. Bonell  A, Lubell  Y, Newton  PN, Crump  JA, Paris  DH. Estimating the burden of scrub typhus: A systematic review. PLoS Negl Trop Dis. 2017;11:e0005838. DOIPubMedGoogle Scholar
  3. Wang  Q, Ma  T, Ding  F, Lim  A, Takaya  S, Saraswati  K, et al. Global and regional seroprevalence, incidence, mortality of, and risk factors for scrub typhus: A systematic review and meta-analysis. Int J Infect Dis. 2024;146:107151. DOIPubMedGoogle Scholar
  4. Chen  K, Travanty  NV, Garshong  R, Crossley  D, Wasserberg  G, Apperson  CS, et al. Detection of Orientia spp. bacteria in field-collected free-living Eutrombicula chigger mites, United States. Emerg Infect Dis. 2023;29:1676–9. DOIPubMedGoogle Scholar
  5. Paddock  CD, Sumner  JW, Comer  JA, Zaki  SR, Goldsmith  CS, Goddard  J, et al. Rickettsia parkeri: a newly recognized cause of spotted fever rickettsiosis in the United States. Clin Infect Dis. 2004;38:805–11. DOIPubMedGoogle Scholar
  6. Ursery  L, Mansour  O, Abernathy  H, Wichmann  E, Yackley  A, Siegler  A, et al. Enhanced surveillance for tick-borne rickettsiosis and ehrlichiosis in North Carolina: Protocol and preliminary results. PLoS One. 2025;20:e0320361. DOIPubMedGoogle Scholar
  7. Gupta  N, Chaudhry  R, Thakur  CK. Determination of cutoff of ELISA and immunofluorescence assay for scrub typhus. J Glob Infect Dis. 2016;8:97–9. DOIPubMedGoogle Scholar
  8. Blacksell  SD, Tanganuchitcharnchai  A, Nawtaisong  P, Kantipong  P, Laongnualpanich  A, Day  NP, et al. Diagnostic accuracy of the InBios Scrub Typhus Detect enzyme-linked immunoassay for the detection of IgM antibodies in northern Thailand. Clin Vaccine Immunol. 2015;23:148–54. DOIPubMedGoogle Scholar
  9. Rawat  V, Singh  RK, Kumar  A, Singh  Y, Chaturvedi  P, Saxena  SR, et al. Diagnostic validation of IgM and IgG ELISA and real-time PCR in detecting scrub typhus infection in endemic regions. J Vector Borne Dis. 2018;55:165–7. DOIPubMedGoogle Scholar
  10. Council of State and Territorial Epidemiologists. Changes to public health reporting and national notification for spotted fever rickettsiosis (including Rocky Mountain spotted fever). Council of State and Territorial Epidemiologists; 2019.

Main Article

1These first authors contributed equally to this article.

Page created: September 30, 2025
Page updated: December 04, 2025
Page reviewed: December 04, 2025
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