Rickettsia

Rickettsia conorii is an obligate intracellular Gram-negative bacterium of the Rickettsiaceae family. It is the causative agent of Mediterranean spotted fever, a tick-borne infectious disease endemic to Mediterranean countries, with seasonal peaks during spring and summer. The disease is transmitted to humans through the bite of infected ticks, mainly of the Rhipicephalus genus.

Clinical characteristics:
After an incubation period of approximately 6 days (ranging from 4 to 20 days), symptoms include high fever, severe headache, muscle and joint pain, and general malaise. A hallmark feature is the presence of a dark, crusted lesion (tache noire) at the site of the tick bite, usually painless.

Two to three days after the onset of fever, a maculopapular skin rash appears, typically affecting the trunk, limbs, and notably the palms and soles, sparing the face. Other symptoms may include enlarged lymph nodes and gastrointestinal manifestations such as nausea, vomiting, or abdominal pain.

Transmission:
The disease is transmitted by the bite of infected ticks that act as vectors after feeding on reservoir animals such as dogs, hares, or hedgehogs. Ticks may also be found on clothing or within domestic environments. Human-to-human transmission does not occur.

Diagnosis:
Diagnosis is primarily clinical, based on symptoms and exposure history. Confirmation can be achieved through serological tests (indirect immunofluorescence) or PCR on blood samples during the acute phase of illness.

Treatment:
The treatment of choice is antibiotic therapy with tetracyclines, particularly doxycycline, which should be started as early as possible. Most patients respond well, with fever subsiding within 48 hours and full recovery occurring within approximately 10 days. The prognosis is excellent with prompt and appropriate treatment.

Prevention:
Preventive measures include avoiding tick bites by wearing protective clothing in endemic areas, using tick repellents, checking for ticks after outdoor exposure, and controlling tick infestations in domestic animals.