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NCT Number: NCT03083197

Scrub Typhus Antibiotic Resistance Trial

Study type: Randomized Control Treatment Trial

Study population: Male and female patients with ≥15 years of age and acute scrub typhus

Duration: 2 years

Study Design: Prospective, open-label, randomized-controlled treatment trial in patients ≥15 years old admitted to hospital with acute scrub typhus. Randomization into 3 oral treatment arms (each n=59 patients, total n=177): i) 7 days of doxycycline, ii) 3 days of doxycycline, and iii) 3 days of azithromycin

Primary Objective: To evaluate the clinical and microbiological responses in scrub typhus patients to three oral treatment regimens: 7 days of doxycycline, 3 days of doxycycline, and 3 days of azithromycin

Secondary Objectives:

1. To perform pharmacokinetic/pharmacodynamics (PK/PD) characterization of the therapeutic responses for doxycycline and azithromycin, incl. serial bacterial load measurements. 2. To define clinical, bacterial, pathophysiological and pharmacological factors associated with disease severity, fever-clearance times (FCT), treatment failures and relapse/re-infection. 3. To determine the minimum inhibitory concentrations (MIC) of clinical Orientia tsutsugamushi isolates to doxycycline, azithromycin and chloramphenicol, using in vitro growth-inhibition assays 4. To genotype all clinical isolates using whole genome sequencing for comparative genomics. 5. To dissect the natural immune response in scrub typhus, using antigen-specific cellular immune and antibody studies, and cytokine profiling

Active, Not Recruiting

This study is active but is not currently recruiting participants.

Key information

Age range

15 year and older

Sex eligibility

All sexes

Study type

Interventional

Phase

Phase 4

Primary location

Shoklo-Malaria Research Unit (SMRU), Mae Sot, Changwat Tak, Thailand

Loading trial locations.

About this study

The funder is USAMRMC - MIDRP and Grant No. DHP-Award D6.7_15_C2_I_15_J9_1317

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Age ≥ 15 years old
  • Hospitalization with acute undifferentiated fever (temperature > 37.5°C, tympanic) ≤14 days or patients admitted to hospital with a history of fever ≤ 14 days who subsequently develop fever within 24 hours of admission
  • Clinically suspected scrub typhus: defined as acute undifferentiated fever with no clear focus of infection and negative malaria blood smear and/or negative malaria RDT. Patients may have one, none, or a combination of other clinical findings such as eschar, rash, lymphadenopathy, headache, myalgia, cough, nausea and abdominal discomfort.
  • A positive scrub typhus RDT (Scrub Typhus IgM RDT, InBios International, Seattle, WA, USA) and/or positive PCR-based detection of O. tsutsugamushi DNA from the admission blood sample
  • Written informed consent and/or, written informed assent as required
  • Able to take oral medication

Exclusion criteria

  • Known hypersensitivity to tetracycline, doxycycline or azithromycin
  • Administration of doxycycline, azithromycin, chloramphenicol, rifampicin, or tetracycline during the preceding 7 days
  • Pregnancy or breast-feeding
  • Patients with myasthenia gravis or systemic lupus erythematosus
  • Patients with an established infection (diagnostic test required) e.g. acute malaria, dengue, leptospirosis, typhoid, Japanese encephalitis etc.
  • Current TB or TB treatment in ≤ 6 months (contain active antibiotics against Orientia spp.)
  • Current HAART use for HIV, long term use of immunosuppressants (e.g. steroids, chemotherapy, TNF-inhibitors and related agents)
  • Patients with severe disease whom the clinical team feel their condition necessitates the need for additional scrub typhus treatment beyond the allocated antibiotic treatment assigned at randomization (e.g. IV chloramphenicol and/or PO/NG rifampicin)

Treatment and study plan

Doxycycline 7 days

Drug

loading dose 200mg PO, then 100mg PO every 12 hours for 7 days

Doxycycline 3 days

Drug

loading dose 200mg PO, then 100mg PO every 12 hours for 3 days

Azithromycin 3 days

Drug

loading dose 1000mg PO on day 1, then 500mg PO every 24 hours on days 2 and 3

Primary outcomes

  1. Fever clearance time (FCT)

    Time frame: at least 24 hours

    Based on the time from first dose of antibiotic treatment to when the tympanic temperature first falls ≤37.5°C and remains ≤37.5°C for at least 24 hours, outside of the influence of paracetamol.

Secondary outcomes

  1. Resolution of bacteraemia in relation to Drug plasma level

    Time frame: 8 Weeks

  2. Occurrence of severe disease or treatment failure/relapse

    Time frame: 8 Weeks

  3. Presence of in vitro antimicrobial resistance

    Time frame: 8 Weeks

    (Minimum inhibitory concentrations (MIC) over susceptibility cut off)

  4. Genotyping of clinical Orientia tsutsugamushi isolates (56kDa gene +/- whole genome sequencing)

    Time frame: 2 years

    Genotyping of clinical OT isolates will be performed on patient samples that are PCR positive (approximately 50-60%) and/or culture positive (approximately 30%). Extracted DNA will be sent for 56kDa gene sequencing +/- whole genome sequencing, revealing the clinically important strains and allowing for comparative analysis with disease severity and patient outcomes.

  5. Antigen-specific positive cellular and humoral immune responses

    Time frame: 8 Weeks

Sponsors and collaborators

Lead sponsor

University of Oxford

Other

Collaborators

  • Chiangrai Prachanukroh Hospital
  • Mae Chan District Hospital
  • Mae Fa Luang District Hospital
  • Mae Suai District Hospital
  • Shoklo Malaria Research Unit

Registry information

Official study title

The Scrub Typhus Antibiotic Resistance Trial (START) Comparing Doxycycline and Azithromycin Treatment Modalities in Areas of Reported Antimicrobial Resistance for Scrub Typhus

Acronym: START

Important dates

Study start
2017
Primary completion
2026
Study completion
2028
First posted
Mar 17, 2017
Registry last updated
Apr 28, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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