boutonneuse fever

Boutonneuse Fever: A Rare Spotted Fever Rickettsiosis

Boutonneuse fever, also known as Mediterranean spotted fever or African tick typhus, is a rare and potentially serious infectious disease caused by the bacterium Rickettsia conorii. This tick-borne illness is characterized by a distinctive rash, fever, and other symptoms.

Key Features:

• Fever: The onset of fever after an incubation period of about 1 week, followed by a centripetally spreading maculopapular rash, which may evolve into a petechial form [4][13].
• Rash: A distinctive pimpled or papular skin rash that follows the fever, often accompanied by headaches, myalgia, and/or arthralgia [5][12].
• Tick exposure: The disease is transmitted through the bite of an infected tick, typically Rhipicephalus sanguineus, which is found in the Mediterranean region, Africa, and India [2][7].

Geographic Distribution:

Boutonneuse fever is endemic in the Mediterranean basin, including countries such as France, Spain, Italy, and Greece. It also occurs in Africa, particularly in North Africa, and in India [1][6][14].

Complications:

While rare, complications of boutonneuse fever can include prolonged fever, reactive arthritis, and in severe cases, death [12]. However, the mortality risk is very low.

In summary, boutonneuse fever is a tick-borne illness characterized by a distinctive rash, fever, and other symptoms. It is relatively rare but potentially serious, and its geographic distribution includes the Mediterranean region, Africa, and India.

Boutonneuse fever, also known as Mediterranean spotted fever or Kenyan tick typhus, is a rickettsial disease that can cause a range of symptoms.

Common signs and symptoms include:

• High fever [6]
• Maculopapular skin rash, which develops primarily on the lower legs and occurs about 2-6 days after the fever [13]
• Eschar (tache noire) at the site of the tick bite [1, 4, 9]
• Headaches [11]
• Myalgia and/or arthralgia [3]
• Regional lymphadenopathy [7]

Other symptoms may include:

• Stupor
• Pulmonary infiltrates
• Bradycardia

It's worth noting that the symptoms of boutonneuse fever can be similar to those of other rickettsial diseases, and a definitive diagnosis is typically made through laboratory testing.

Diagnostic Tests for Boutonneuse Fever

Boutonneuse fever, also known as Mediterranean spotted fever (MSF), can be diagnosed through a combination of clinical symptoms and laboratory tests.

• Clinical Diagnosis: The diagnosis is commonly made based on a history of travel to an endemic location and clinical findings: fever, tache noire at the site of the tick bite, erythemato-papular rash, and prompt response to chloramphenicol or tetracycline treatment [12].
• Serologic Testing: Serologic testing is the mainstay of diagnosis for boutonneuse fever. This includes Enzyme-Linked Immunosorbent Assay (ELISA), indirect immunofluorescence tests, and other serological methods [10][9]. These tests can detect antibodies against Rickettsia conorii, the causative agent of the disease.
• PCR and Molecular Tests: Polymerase Chain Reaction (PCR) and molecular tests are also available for diagnosing boutonneuse fever. These tests can detect the genetic material of Rickettsia conorii in blood samples [4][5].
• Other Laboratory Tests: Other laboratory tests, such as blood cultures and immunoblotting, may be used to confirm the diagnosis.

Challenges in Diagnosis

The diagnosis of boutonneuse fever can be challenging, especially during the early stages of illness. The disease often presents with non-specific symptoms, making it difficult to diagnose based on clinical findings alone [7]. Therefore, laboratory tests play a crucial role in confirming the diagnosis.

References

[10] Boutonneuse fever (BF) is an eruptive disease and is classified as a spotted fever, which is endemic in the Mediterranean region. [9] The diagnosis of Boutonneuse Fever usually depends on clinical evidence (summer occurrence, fever, tache noire at the site of the tick bite, in 30-70% of cases, erythemato -papular rash, prompt response to chloramphenicol or tetracycline treatment). [12] The diagnosis is made with serologic methods, either the classic Weil–Felix test, ELISA, or indirect immunofluorescence tests. [7] Laboratory confirmation is made by blood tests, PCR or immun biopsied tissues, or culture.

Treatment Options for Boutonneuse Fever

Boutonneuse fever, also known as Mediterranean spotted fever (MSF), requires prompt and effective treatment to reduce morbidity, prevent complications, and eradicate the infection.

• Doxycycline: The preferred drug treatment is doxycycline, a tetracycline antibiotic, which should be administered for 7-14 days [8][11]. This medication inhibits bacterial DNA synthesis and growth, making it an effective choice for treating MSF.
• Chloramphenicol: Another effective regimen is chloramphenicol, which should be taken in doses of 2 g/day for 7-10 days [9].
• Ciprofloxacin: Ciprofloxacin is also a viable option, with recommended dosages of 1.5 g/day for 5-7 days [9].
• Rifampin: Rifampin is considered a safe drug for treating Mediterranean Spotted Fever or Boutonneuse Fever and can be used to prevent complications, reduce morbidity, and eradicate the infection [14].

Important Considerations

• Treatment should be continued for at least 2 days after signs and symptoms have resolved [3].
• Doxycycline is the only antibacterial agent recommended for treatment of all tickborne rickettsial diseases, including MSF [7].
• Immediate empiric treatment with a tetracycline (most commonly doxycycline) is recommended for patients of all ages [8].

References

[3] - A list of common medications used to treat or reduce the symptoms of boutonneuse fever. [7] - Doxycycline is the only antibacterial agent recommended for treatment of all tickborne rickettsial diseases, including MSF. [8] - Immediate empiric treatment with a tetracycline (most commonly doxycycline) is recommended for patients of all ages. [9] - Other effective regimens are chloramphenicol (2 g/day for 7–10 days) or ciprofloxacin (1.5 g/day for 5–7 days). [11] - The preferred drug treatment is doxycycline for seven days to fourteen days while erythromycin in pregnant women is not as effective as the other options. [14] - Rifampin is also considered to be a safe drug for treating Mediterranean Spotted Fever or Boutonneuse Fever.

Differential Diagnosis of Boutonneuse Fever

Boutonneuse fever, also known as Mediterranean spotted fever (MSF), requires prompt differential diagnosis to ensure immediate treatment and prevent complications.

• Rocky Mountain Spotted Fever (RMSF): While RMSF is caused by a different bacterium, it presents with similar symptoms, including fever, rash, and eschar. However, the case fatality rate for RMSF is significantly higher than that of Boutonneuse fever [3].
• African Tick-Bite Fever: This disease also presents with fever, rash, and eschar, but it is caused by a different bacterium and has a lower mortality risk compared to RMSF [5].
• Malaria: In areas where malaria is endemic, it should be considered in the differential diagnosis of Boutonneuse fever, especially in patients returning from tropical regions [6].
• Other Rickettsial Diseases: African tick-bite fever, Rickettsia parkeri rickettsiosis, and Queensland tick typhus are other diseases that may present with similar symptoms and require consideration in the differential diagnosis [13].

Key Diagnostic Features

To diagnose Boutonneuse fever accurately, clinicians should look for:

• Fever: A high fever is a common symptom of Boutonneuse fever.
• Rash: A characteristic rash, often described as pimpled or papular, follows the fever.
• Tache Noire (Eschar): The presence of an eschar at the site of the tick bite is a distinctive feature of Boutonneuse fever [1].
• History of Tick Bite and/or Travel to Endemic Area: A history of recent contact with a dog or travel to an area where the disease is known to exist can raise suspicion for Boutonneuse fever.

References

[1] Context 1: Boutonneuse fever (BF), also known as Mediterranean spotted fever (MSF), is transmitted by the dog tick Rhipicephalus sanguineus. The tick bite causes a characteristic rash and a distinct mark—namely, a tache noire (eschar).

[3] Context 3: While RMSF is caused by a different bacterium, it presents with similar symptoms, including fever, rash, and eschar. However, the case fatality rate for RMSF is significantly higher than that of Boutonneuse fever.

[5] Context 5: African tick-bite fever also presents with fever, rash, and eschar, but it is caused by a different bacterium and has a lower mortality risk compared to RMSF.

[6] Context 6: In areas where malaria is endemic, it should be considered in the differential diagnosis of Boutonneuse fever, especially in patients returning from tropical regions.

[13] Context 13: The differential diagnosis of a patient with an eschar and fever includes ecthyma gangrenosum, herpetic dermatitis, aspergillosis, cutaneous leishmaniasis, tularemia, melioidiosis, and cutaneous anthrax; however, several other rickettsial diseases, including African tick-bite fever, Rickettsia parkeri rickettsiosis, boutonneuse fever, Queensland tick typhus, should also be considered.