Eruptive rickettsioses


Eruptive fevers caused by bacteria of the genus Rickettsia and transmitted to man by an arthropod vector. Three main groups are distinguished: typhus group, spotted fever group and scrub typhus group.

Clinical features

– Common to all forms:
• Sudden onset of fever (temperature of over 39 °C) with severe headache and myalgias.
• 3 to 5 days later; onset of generalised cutaneous eruption (see below).
• Hypotension; non-dissociated rapid heart rate (variable).
• Typhoid state: prostration, omnubilation, confusion and extreme asthenia, particularly marked in typhus forms.
• Inoculation eschar: painless, black crusted lesion surrounded by a erythematous halo at the site of the bite. Always check for this significant sign.
• Non-cutaneous signs vary from one form to another, and are atypical and variable (see below).

Group Typhus Spotted fever Scrub typhus

Form

Epidemic typhus

Murine typhus

Mediterranean
spotted fever

Rocky Mountain spotted fever

Other Old-World tick-borne fevers

Scrub typhus

Pathogen

R. prowasekii

R. typhi

R. conorii

R. rickettsii

R. sibirica, R. australis

O. tsutsugamushi

Vector

body lice

rat fleas

ticks

ticks

ticks

mites

Reservoir

man

rats

dogs

rodents

rodents, dogs, etc.

rodents

Occurence

epidemic

endemic

endemic

endemic

endemic

sporadic

Geographical distribution

worldwide, conflicts; main sites: Burundi/Rwanda, Ethiopia

worldwide

around the mediterranean,
Sub-Saharan Africa

North America,
Central America,
Columbia, Brazil

Southern Africa, Australia, Siberia

Extrême-Orient, Inde, Pacifique Sud

Rash

maculopapular

maculopapular

maculopapular

purpural

maculopapular

macular

Eschar

0

0

black necrotic area

rare

black necrotic area

black necrotic area

Typhoid state

+++

+++

+/-

+/-

+/-

+++

Extra-cutaneous signs

cough, myalgia, meningeal signs

gastrointestinal signs

meningeal signs

gastrointestinal and neurological signs, hypotension

variables

meningeal signs

Case fatality (%)

30 (without treatment)

5

2

5

1

0-30

– Complications can be severe, and sometimes fatal: encephalitis, myocarditis, hepatitis, acute renal failure, haemorrhage etc.

Laboratory

Detection of specific IgM of each group by indirect immunofluorescence. The diagnosis is confirmed by 2 serological tests at an interval of 10 days. In practice, clinical signs and the epidemiological context are sufficient to suggest the diagnosis and start treatment.

Treatment

– Symptomatic treatment:
• Hydration (PO or IV if the patient is unable to drink).
• Fever: paracetamol PO (Chapter 1). Acetylsalicylic acid (aspirin) is contra-indicated due to the risk of haemorrhage.

– Antibiotic therapy1 for 5 to 7 days or until 3 days after the fever has disappeared:
doxycycline PO (except in pregnant or lactating women)
Children over 8 years: 50 mg 2 times daily or 100 mg once daily 
Adult: 100 mg 2 times daily or 200 mg once daily 

– In a context of epidemic typhusdoxycycline PO is the choice treatment, but there is a risk of recurrence:
Children under 8 years: 4 mg/kg (max. 100 mg) single dose 
Children over 8 years: 100 mg single dose
Adults: 200 mg single dose

Note: doxycycline is usually contraindicated in pregnant or breast-feeding women and children under 8 years. However, the administration of a single dose should not, in theory, provoke adverse effects. Check national recommendations.

Prevention

– Epidemic typhus: control of body lice (see Pediculosis, Chapter 4).
– Murine typhus: control of fleas and then rats.
– Spotted fevers: avoid tick bites by wearing clothing and using repellents.
– Scrub typhus: use of repellents, chemoprophylaxis with doxycycline PO (200 mg once weekly in adults).



Footnotes
Ref Notes
1 Unlike borrelioses, antibiotic treatment of rickettsioses does not provoke a Jarisch-Herxheimer reaction. However, the geographical distribution of borrelioses and rickettsioses may overlap, and thus a reaction may occur due to a possible co-infection (see Borreliosis).