Rickettsial diseases

Overview 
Theory 
Diagnosis 
Management 
Follow up 
Resources 

Please note that formulations/routes and doses may differ between drug names and brands, drug formularies, or locations. Treatment recommendations are specific to patient groups: see disclaimer

ACUTE

suspected or confirmed rickettsial infection: not pregnant or breastfeeding

1st line – doxycycline or tetracycline

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1st line –

doxycycline or tetracycline

It is important to start appropriate empirical antibiotic therapy as soon as rickettsial infection is reasonably considered in the differential, without waiting for the results of tests to confirm the diagnosis.

The first-line treatment for all rickettsial diseases in people of all ages is doxycycline (a tetracycline class antibiotic).[22] Doxycycline can be given as oral or intravenous therapy depending on the severity of symptoms. A clinical response, including abatement of fever, should be evident in 48 to 72 hours.[29] Doxycycline should be continued for at least 3 days after clinical improvement is seen, a typical course being 5 to 7 days.[22]

Doxycycline is the drug of choice for children with rickettsial infections.[22] Although repeated courses of tetracycline were associated with staining of permanent teeth in young children, no evidence suggests that doxycycline causes any such tooth staining.[33][34][35] CDC: research on doxycycline and tooth staining Opens in new window

Tetracycline may also be used in children >8 years of age and adults; however, doxycycline has a more convenient dosing schedule and can be used in younger children, so is the preferred option.

Primary options

doxycycline: children <45 kg body weight: 2.2 mg/kg orally/intravenously twice daily; children ≥45 kg body weight and adults: 100 mg orally/intravenously twice daily

Secondary options

tetracycline: children >8 years of age: 25-50 mg/kg/day orally given in 4 divided doses, maximum 2000 mg/day; adults: 250-500 mg orally four times daily

2nd line – alternative antibiotic therapy

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2nd line –

alternative antibiotic therapy

If the patient is allergic to tetracyclines, an infectious disease consultant and/or an allergy and immunology specialist should be consulted.[22]

Azithromycin is a suitable alternative in patients with scrub typhus and a severe doxycycline allergy.[30] Low-quality evidence suggests that it is as effective as doxycycline and tetracycline for the treatment of scrub typhus in terms of treatment failure and time to defervescence.[31] Rifampicin is an alternative option for patients with scrub typhus and a severe doxycycline allergy.[30] Chloramphenicol is another option, but its use is limited by adverse haematological effects.[22][30] Consult a specialist for guidance on a suitable regimen.

meningococcal or other pyogenic infectious disease or staphylococcal sepsis or toxic shock syndrome cannot be excluded

Plus – empirical antibiotic therapy

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Plus –

empirical antibiotic therapy

Treatment recommended for ALL patients in selected patient group

For patients whose presentation may be consistent with a serious, different bacterial infection, therapy needs to begin presumptively, and empirical antibiotics are indicated until blood cultures or clinical course rule out the alternative diagnosis.

An antibiotic active against Neisseria meningitidis, such as a parenteral third-generation cephalosporin, is also appropriate for other bacterial infections that can occasionally mimic rickettsial spotted fevers (e.g., pneumococcal bacteraemia in asplenic hosts).[22] If sepsis or toxic shock syndrome caused by Staphylococcus aureus cannot be excluded, empirical therapy is appropriate. Treatment is continued until cultures and clinical course exclude other infections.

See Meningococcal disease, Sepsis, or Toxic shock syndrome for more information.

critically ill

Plus – aggressive supportive therapy

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Plus –

aggressive supportive therapy

Treatment recommended for ALL patients in selected patient group

Some patients with rickettsial infection may be extremely unwell and close to death. This is particularly true of scrub typhus. Intensive medical support in the intensive care unit is urgently required. Fluid balance and serum electrolytes should be monitored closely. Some patients may need transfusions of packed red blood cells or platelets. Critically ill patients might require adjunctive therapies for seizures, intracranial hypertension, shock, or disseminated intravascular coagulation.[22][36]

suspected or confirmed rickettsial infection: pregnant or breastfeeding

1st line – doxycycline

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1st line –

doxycycline

The care of pregnant women with rickettsial infection should be undertaken in consultation with an infectious disease consultant. Maternal infection with scrub typhus has been associated with poor maternal and neonatal outcomes (including high miscarriage rates).[5]

Tetracyclines as a group are generally contraindicated in pregnant women, due to their potential toxicity to both fetus and mother.[22] However, a review of the evidence suggested that the safety profile of doxycycline is significantly different to other tetracyclines and that there was no correlation between use of doxycycline and teratogenic effects.[35] Low levels of doxycycline are excreted in breast milk. The use of a short course (5 to 7 days) of doxycycline typically recommended for treatment of rickettsial diseases is probably safe during lactation.[22]

Treatment alternatives for pregnant women may include azithromycin, chloramphenicol, or rifampicin; however, a specialist should decide the most appropriate regimen on a case by case basis. Caution is advised when using chloramphenicol late in the third trimester of pregnancy due to a theoretical risk of grey baby syndrome.[22]