Approach Considerations

The current treatment for scrub typhus is administration of a tetracycline (most commonly doxycycline).^[59]Chloramphenicol is also effective, and macrolides have been used as well. Relapses may occur if the antibiotics are not taken for a long enough period. Intravenous (IV) antibiotics may be administered to patients who are seriously ill and unable to swallow pills.

When patients who are HIV-positive become infected with certain strains of scrub typhus, their viral load can dramatically decrease. This is an important area of research. A proposed hypothesis is that patients infected with HIV who acquire scrub typhus have a powerful immune response raised to the scrub typhus and that is being turned against the HIV.^[60]

Diet and activity are as tolerated. Inpatient care may be necessary for patients with severe scrub typhus. In such cases, meticulous supportive management is necessary to abort progression to disseminated intravascular coagulation (DIC) or circulatory collapse.

Pharmacologic Treatment

To reduce morbidity and mortality, treatment of scrub typhus must be initiated early in the course of the disease, on the basis of a presumptive diagnosis. Patients respond more promptly than in rickettsial infections, with resolution of fever expected within 24-36 hours.

The treatment of choice is tetracycline or doxycycline.^[61](O tsutsugamushi strains with reduced susceptibility to doxycycline have been identified, especially in northern Thailand.^{[8, 5, 62]}) A 7-day antibiotic regimen is usually effective.^[4]Relapse may occur and necessitate administration of additional courses of antibiotics.^[38]

Newer macrolides may be appropriate for children and pregnant women.^{[8, 38]}In a small trial, azithromycin was shown to have efficacy comparable to that of doxycycline.^[48]Rifampin and azithromycin have been used successfully in areas where scrub typhus is resistant to conventional therapy.^{[5, 8, 63]}

In another small trial, roxithromycin was as effective as doxycycline and chloramphenicol for the treatment of scrub typhus^[64]; however, a subsequent study found it to be ineffective.^[34]In a prospective, open-label, randomized trial of Korean patients with mild-to-moderate scrub typhus, the efficacy and safety of a 5-day telithromycin regimen compared favorably with those of a 5-day doxycycline regimen.^[65]

Studies of fluoroquinolones have yielded mixed results, and their use cannot be advocated at this time.^{[61, 66, 67]}

Consultation with an infectious diseases specialist should be considered if the patient does not improve on antibiotics or has atypical symptoms. The persistence of viable O tsutsugamushi was evaluated in patients who had recovered from scrub typhus.^[68]O tsutsugamushi may cause a chronic latent symptomatic infection in spite of what is now considered adequate antibiotic therapy.

Further studies are needed to improve antibiotic treatment of severe and resistant scrub typhus, as well as to improve treatment in children and pregnant women.

Prevention

Preventive measures in endemic areas include the use of protective clothing and insect repellents (potentially including plant essential oils^[69]). Short-term vector reduction using environmental insecticides and vegetation control can be instituted.

Chemoprophylaxis regimens have included the following:

A single dose of doxycycline given weekly, started before exposure and continued for 6 weeks after exposure^[1]
A single oral dose of chloramphenicol or tetracycline given every 5 days for a total of 35 days, with 5-day nontreatment intervals

Reports of scrub typhus outbreaks in endemic areas and decreased effectiveness of antibiotic treatment suggest a continued need for a suitable vaccine.^[70]At present, no such vaccine is available.^[71]

Medication

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Media Gallery

Transmission electron micrograph depicts peritoneal mesothelial cell of mouse that had been experimentally infected intraperitoneally with Orientia tsutsugamushi. Several organisms are visible within mesothelial cell's cytoplasm.
Eschar on neck.
Eschar on scrotum.
Typical eschar.
Maculopapular rash.
Chigger. Image taken from "Food and Environmental Hygiene Department" Web site and is reproduced under license from the Government of Hong Kong Special Administrative Region.

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Author

David J Cennimo, MD, FAAP, FACP, FIDSA, AAHIVS Associate Professor of Medicine and Pediatrics, Adult and Pediatric Infectious Diseases, Rutgers New Jersey Medical School

David J Cennimo, MD, FAAP, FACP, FIDSA, AAHIVS is a member of the following medical societies: American Academy of HIV Medicine, American Academy of Pediatrics, American College of Physicians, American Medical Association, HIV Medicine Association, Infectious Diseases Society of America, Medical Society of New Jersey, Pediatric Infectious Diseases Society

Disclosure: Nothing to disclose.

Coauthor(s)

Arry Dieudonne, MD Associate Professor of Pediatrics, Division of Pulmonology, Allergy, Immunology and Infectious Diseases, Rutgers New Jersey Medical School; Clinical Director, Francois-Xavier Bagnold Center for Children, University Hospital

Arry Dieudonne, MD is a member of the following medical societies: American Academy of Pediatrics, American Medical Association, Pediatric Infectious Diseases Society

Disclosure: Nothing to disclose.

Chief Editor

Russell W Steele, MD Clinical Professor, Tulane University School of Medicine; Staff Physician, Ochsner Clinic Foundation

Russell W Steele, MD is a member of the following medical societies: American Academy of Pediatrics, American Association of Immunologists, American Pediatric Society, American Society for Microbiology, Infectious Diseases Society of America, Louisiana State Medical Society, Pediatric Infectious Diseases Society, Society for Pediatric Research, Southern Medical Association

Disclosure: Nothing to disclose.

Acknowledgements

David F Butler, MD Professor of Dermatology, Texas A&M University College of Medicine; Chair, Department of Dermatology, Director, Dermatology Residency Training Program, Scott and White Clinic, Northside Clinic

David F Butler, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Dermatology, American Medical Association, American Society for Dermatologic Surgery, American Society for MOHS Surgery, Association of Military Dermatologists, and Phi Beta Kappa