Published Date: January 1, 2023
Authors: Kevin MacConnachie, Kevin Tishkowski
2023 Jul 3. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan–.
Boutonneuse fever (BF) is an illness first detailed in Tunisia, North Africa, nearly a century ago and was called “boutonneuse” (French for “spotty”) because of the pimpled or papular skin rash that followed the fever. Boutonneuse fever is a type of infectious disease caused by bacteria of the rickettsia genus, typically found in the Mediterranean region of Europe. Other common regions include sub-Saharan Africa, India, Greece, and select regions surrounding the Black Sea.
Rickettsia conorii (the causative organism) is an obligate intracellular bacterium that cannot reproduce outside of a host cell. It is a type of gram-negative bacteria (it does not retain the crystal violet stain during the Gram staining technique of bacterial identification).
Boutonneuse fever is transmitted by the bite of a dog tick (Rhipicephalus sanguineus) and is classified as a spotted fever; most people that get sick with a spotted fever will have a black eschar (a “tache noire” or black spot) at the site of the bite. The tick bite causes the zoonotic (non-human to human) bacteria to enter the blood and disseminate.
Boutonneuse fever typically has an incubation period of 5 to7 days following the tick bite. The tick bite is usually painless and may not be noticed if it occurs in an inconspicuous location. The diagnosis is commonly made based on a history of travel to an endemic location and clinical findings: fever, exanthem (rash), and the tache noire (black eschar). This disease that follows classically causes flu-like symptoms. It typically follows a similar, yet more benign clinical course compared to that of Rocky Mountain spotted fever but can occasionally cause more advanced signs and symptoms such as hepatomegaly, jaundice, meningitis, other neurologic complications, orchitis, retinopathy, gastrointestinal bleeding, and pneumonia.
Treatment of BF is largely the same as for all rickettsial infections. Doxycycline is a tetracycline that remains useful in the management of obligately intracellular bacterial pathogens such as rickettsia. Patients with a more benign progression are treated with antibiotics for 7 days. Those with more progressive symptoms are usually treated for 14 days. Macrolides such as azithromycin are efficacious in children and pregnant women.