A79.9
DESCRIPTION
A tick-borne febrile illness caused by Rickettsia conorii or africae .
The rash appears on days 3–5 of the illness. It spreads from the extremities to the trunk, neck, face, palms, and soles within 36 hours.
The lesions progress from macular to maculopapular and may persist for 2–3 weeks.
Atypical cutaneous findings may occur.
Complications include:
- vasculitis,
- encephalitis,
- thrombosis,
- renal failure,
- myocarditis,
- pneumonitis, and
- thrombocytopaenia.
DIAGNOSTIC CRITERIA
The diagnosis is made on clinical grounds.
Clinical
- Fever, headache, malaise, myalgia and arthralgia.
- Maculopapular rash that may involve the palms and soles.
- Eschar at the site of the tick bite is associated with regional lymphadenopathy and splenomegaly.
Investigations
- Initiate treatment empirically.
- If diagnostic uncertainty: PCR on blood sample or on swab from base of eschar.
- Do not perform serology.
GENERAL AND SUPPORTIVE MEASURES
- Remove tick as soon as possible after detection.
MEDICINE TREATMENT
Antibiotic therapy
Treatment must be started before confirmation of diagnosis.
Doxycycline is the drug of choice for all children with tick bite fever (despite usually not being recommended for use in children < 8 years).
- Doxycycline, oral.
- If < 50 kg: 4 mg/kg/24 hours in 2 divided doses on the first day, then 2 mg/kg/24 hours in 2 divided doses for 7 days.
- If > 50 kg: 100 mg 12 hourly for 7 days.
If unable to take oral therapy:
- Azithromycin, IV, 10 mg/kg/day for 5 days.
REFERRAL
- Patients not responding to adequate therapy.
- Patients with complications.