Scrub typhus: Treatment and prevention
- Daniel J Sexton, MD
Daniel J Sexton, MD
- Editor-in-Chief — Infectious Diseases
- Section Editor — Bacterial Infections
- Professor of Medicine
- Duke University Medical Center
Scrub typhus is a mite-borne infectious disease caused by Orientia tsutsugamushi (previously called Rickettsia tsutsugamushi). It is distributed throughout the Asia Pacific rim, being endemic in Korea, China, Taiwan, Japan, Pakistan, India, Thailand, Malaysia, and northern portions of Australia. However, cases also occur in the United States, Canada, and Europe, being imported by tourists returning from endemic regions.
Scrub typhus is manifested clinically by high fever, intense generalized headache, diffuse myalgias, and, in many patients, rash and an eschar at the site of the chigger bite. The diagnosis is suggested by the clinical history (including visit to an endemic area) and physical findings and confirmed by serologic testing or biopsy of an eschar. (See "Scrub typhus: Clinical features and diagnosis".)
Scrub typhus lasts for 14 to 21 days without treatment. Severe infections may be complicated by interstitial pneumonia, pulmonary edema, congestive heart failure, circulatory collapse, and a wide array of signs and symptoms of central nervous system dysfunction, including delirium, confusion, and seizures. Death may occur as a result of these complications, usually late in the second week of the illness.
By contrast, patients treated with appropriate antibiotics typically become afebrile within 48 hours of starting therapy . This response to treatment may be useful diagnostically; failure of defervescence within 48 hours is often considered evidence that scrub typhus is not present, and that an alternate diagnosis such as malaria or dengue should be considered. However, in a 2004 report, 20 of 93 patients with serologically confirmed scrub typhus had a delay in defervescence to more than 48 hours, making the reliability of this long-standing clinical truism suspect . The authors of another report retrospectively examined the clinical characteristics of 18 patients with Q fever (9), scrub typhus (7) or murine typhus (2) who failed to respond within 48 hours to treatment with doxycycline and compared their clinical features to 88 cases who responded promptly. Delayed defervescence was associated with jaundice and relative bradycardia .
Chloramphenicol was the first drug shown to be effective in the treatment of scrub typhus, and is still commonly used in endemic regions. Doses of 250 to 500 mg orally or intravenously every six hours are effective. However, doxycycline (100 mg orally or intravenously twice daily) is now the drug of choice for this illness. Azithromycin has been advocated as an alternative agent in special circumstances.
- Sheehy TW, Hazlett D, Turk RE. Scrub typhus. A comparison of chloramphenicol and tetracycline in its treatment. Arch Intern Med 1973; 132:77.
- Kim YS, Yun HJ, Shim SK, et al. A comparative trial of a single dose of azithromycin versus doxycycline for the treatment of mild scrub typhus. Clin Infect Dis 2004; 39:1329.
- Lai CH, Huang CK, Weng HC, et al. Clinical characteristics of acute Q fever, scrub typhus, and murine typhus with delayed defervescence despite doxycycline treatment. Am J Trop Med Hyg 2008; 79:441.
- Panpanich R, Garner P. Antibiotics for treating scrub typhus. Cochrane Database Syst Rev 2000; :CD002150.
- Lee N, Ip M, Wong B, et al. Risk factors associated with life-threatening rickettsial infections. Am J Trop Med Hyg 2008; 78:973.
- Brown GW, Saunders JP, Singh S, et al. Single dose doxycycline therapy for scrub typhus. Trans R Soc Trop Med Hyg 1978; 72:412.
- Song JH, Lee C, Chang WH, et al. Short-course doxycycline treatment versus conventional tetracycline therapy for scrub typhus: a multicenter randomized trial. Clin Infect Dis 1995; 21:506.
- Kim YS, Lee HJ, Chang M, et al. Scrub typhus during pregnancy and its treatment: a case series and review of the literature. Am J Trop Med Hyg 2006; 75:955.
- McGready R, Prakash JA, Benjamin SJ, et al. Pregnancy outcome in relation to treatment of murine typhus and scrub typhus infection: a fever cohort and a case series analysis. PLoS Negl Trop Dis 2014; 8:e3327.
- Meena M, Rohilla M, Jain V, et al. Scrub typhus in pregnancy: a case series. Trop Doct 2016; 46:153.
- Strickman D, Sheer T, Salata K, et al. In vitro effectiveness of azithromycin against doxycycline-resistant and -susceptible strains of Rickettsia tsutsugamushi, etiologic agent of scrub typhus. Antimicrob Agents Chemother 1995; 39:2406.
- Phimda K, Hoontrakul S, Suttinont C, et al. Doxycycline versus azithromycin for treatment of leptospirosis and scrub typhus. Antimicrob Agents Chemother 2007; 51:3259.
- Jang MO, Jang HC, Kim UJ, et al. Outcome of intravenous azithromycin therapy in patients with complicated scrub typhus compared with that of doxycycline therapy using propensity-matched analysis. Antimicrob Agents Chemother 2014; 58:1488.
- Watt G, Kantipong P, Jongsakul K, et al. Doxycycline and rifampicin for mild scrub-typhus infections in northern Thailand: a randomised trial. Lancet 2000; 356:1057.
- Chattopadhyay S, Richards AL. Scrub typhus vaccines: past history and recent developments. Hum Vaccin 2007; 3:73.
- ANDREW R, BONNIN JM, WILLIAMS S. Tick typhus in North Queensland. Med J Aust 1946; 2:253.