Scrub Typhus Antibiotic Resistance Trial

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)