What is Boutonneuse fever?
Boutonneuse fever is one of a group of several tick-borne spotted fever illnesses, including Rocky Mountain spotted fever, that are caused by closely-related rickettsiae (tiny bacteria in the genus Rickettsia).
Rickettsia conorii is the agent of Boutonneuse fever. The name for Boutonneuse fever arises from the black “button-like" (French “bouton") ulcer that occurs at the site of the tick bite. Boutonneuse fever sometimes goes by other names, often based upon the geographic location of occurrence, including Mediterranean spotted fever (most commonly), Mediterranean tick fever, Marseilles fever, Kenya tick typhus, South African tick typhus, India tick typhus, and Israeli tick typhus.
How is Boutonneuse fever tansmitted?
Boutonneuse fever is transmitted by the bite of a brown dog tick (Rhipicephalus sanguineus) that is infected with
the pathogen
R. conorii.
Rhipicephalus sanguineus ticks maintain
R. conorii in nature through transovarial passage (female tick to her eggs) and transstadial passage (from stage to stage during the tick’s life cycle). SinceR. sanguineus ticks are found (feed) mainly on dogs, people who have close contact with dogs are at a higher risk of exposure to potentially infected ticks. Rarely, infection may occur when crushed tissues or feces of the tick enter the body through breaks in the skin or the mucous membranes. Brown Dog Tick adult and nymph
before and after engorgement.
How common is Boutonneuse fever?
Boutonneuse fever is found in those parts of Europe and the Middle East that are adjacent to the Mediterranean, Black, and Caspian Seas. It also occurs throughout India as well as other locations within Africa. The true incidence is unknown. Because infection is often very mild, cases may go undiagnosed, may be misdiagnosed, or may simply not be reported. In the Mediterranean region, the incidence is estimated at 50 cases per 100,000 per year. In Croatia, 52% of a study population with a recent history of tick bite had antibodies to
R. conorii. In Portugal, as many as 20,000 cases are estimated to occur each year, but only about 5% are reported.**
What are the symptoms of Boutonneuse fever?
Symptoms of Boutonneuse fever begin abruptly 5-7 days after an infective tick bite, and often include high fever, severe headache, a tache noir (small black ulcer or scab, approximately 2-5 mm in diameter, at the site of the tick bite), and a widespread red maculopapular rash (both flat and raised spots) that is especially prominent on the legs, feet (soles) and hands (palms). Symptoms may also include myalgia (muscle aches), arthralgia (joint pain), chills, malaise (generalized, overall feeling of discomfort – feeling “unwell”), nausea, vomiting, and conjunctivitis. Severe complications can occur, especially in the elderly, or in those patients who have underlying disease or who are immunocompromised. The case-fatality rate for Boutonneuse fever is less than 3% even without specific treatment.
How is Boutonneuse fever diagnosed?
Boutonneuse fever should be suspected in a patient who has fever, rash, and a tache noir, especially when there is a history of tick bite and/or travel to an endemic area (location where the disease is known to exist). Recent contact with a dog may also raise suspicion. Prompt differential diagnosis is critical, ensuring immediate treatment is initiated in the event the symptoms are due to another, more severe, illness (e.g. Rocky Mountain spotted fever). Laboratory confirmation is made by blood tests, PCR or immunostains of biopsied tissues, or culture.
How is Boutonneuse fever treated?
Antibiotic therapy is important to shorten the course of illness, prevent complications, and eradicate the infection. Doxycycline is the drug of choice, although chloramphenicol and quinolones are also effective. Macrolides such as azithromycin and clarithromycin have been shown to be efficacious in children, or as alternatives to doxycycline in adults. Patients typically improve within 24 hours after initiation of treatment, and a delay in response should cast doubt upon the diagnosis. Since rickettsial diseases can be so severe in some cases, treatment should be initiated immediately upon suspicion without waiting for laboratory confirmation of the diagnosis.
How can I protect myself against Boutonneuse fever?
There is no vaccine against Boutonneuse fever. Therefore, in order to prevent this illness, as well as other tick-borne diseases, you must protect yourself from tick bites.
When in tick habitat (tall grass and weeds, scrubby areas, woods and leaf litter), follow these precautions:
- Wear proper clothing as a physical barrier against ticks – long pants tucked into boots or tightly-woven socks; long sleeve shirt; shirt tucked into pants; and light-colored clothing so as to more easily spot ticks.
- Check your skin and clothing periodically for ticks.
- Use both skin and clothing repellents that have been approved by the Environmental Protection Agency (EPA). They are safe and effective. Always FOLLOW LABEL DIRECTIONS.
- For optimum protection, soldiers should utilize the DOD INSECT REPELLENT SYSTEM.
Select the image for more information on the DoD Insect Repellent System.
