DDx
Diagnostic Considerations
The malignant form of boutonneuse fever (MSF) is diagnosed on the basis of specific combinations of laboratory findings and clinical symptoms.
Laboratory findings indicative of malignant MSF when combined with clinical symptoms (see below), are as follows (≥2 required):
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Thrombocytopenia (< 100 X 10 9/L)
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Renal failure (creatinine level >150 mmol/L)
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Hyponatremia (< 130 mmol/L)
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Hypocalcemia (< 2.1 mmol/L)
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Hypoxemia (arterial oxygen pressure < 80 mm Hg)
Clinical symptoms indicative of malignant BF when combined with laboratory findings (see above), are as follows (≥2 required):
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Purpuric rash
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Stupor
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Pulmonary infiltrates
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Bradycardia
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Coma
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Jaundice
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Gastrointestinal bleeding
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Arthralgic and myalgic arthritis
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Hepatomegaly and splenomegaly
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Orchitis
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Conjunctival hyperemia
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Meningism [26]
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Local lymphadenopathy
In addition to the conditions listed in the differential diagnosis, other problems to be considered include the following:
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Hepatitis
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Aseptic acute arthritis
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Small-vessel vasculitis
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Sepsis
Differentials
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Rickettsia parkeri Rickettsiosis
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African Tick bite fever
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Meningococcemia
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Disseminated gonococcal infection
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Toxic Shock Syndrome
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Syphilis
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Parvovirus B19
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Erythema multiforme
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Toxic Epidermal Necrolysis
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Crimean-Congo hemorrhagic fever
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Omsk hemorrhagic fever
Media Gallery
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Distribution and incidence of Mediterranean spotted fever (boutonneuse fever). Courtesy of Professor Didier Raoult, Unité des Rickettsies, Marseille, France [Rovery C, Brouqui P, Raoult D. Questions on Mediterranean spotted fever a century after its discovery. Emerg Infect Dis. 2008 Sep; 14(9): 1360–1367. Online at: https://wwwnc.cdc.gov/eid/article/14/9/07-1133_article.].
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Rhipicephalus sanguineus (brown dog tick), found worldwide. Courtesy of Jim Occi Photography (https://jimocci.photoshelter.com/).
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Eschar (tache noire) at site of tick bite on chest. Courtesy of José A Oteo, MD, Centro de Rickettsiosis y Enfermedades Transmitidas por Artrópodos Vectores, Hospital Universitario San Pedro - Centro de Investigación Biomédica de La Rioja (CIBIR).
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Maculopapular purpuric rash in Mediterranean spotted fever involving extremities. Courtesy of José A Oteo, MD, Centro de Rickettsiosis y Enfermedades Transmitidas por Artrópodos Vectores, Hospital Universitario San Pedro - Centro de Investigación Biomédica de La Rioja (CIBIR).
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Maculopapular purpuric rash in Mediterranean spotted fever (close up). Courtesy of José A Oteo, MD, Centro de Rickettsiosis y Enfermedades Transmitidas por Artrópodos Vectores, Hospital Universitario San Pedro - Centro de Investigación Biomédica de La Rioja (CIBIR).
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Maculopapular rash in Mediterranean spotted fever involving palms. Courtesy of José A Oteo, MD, Centro de Rickettsiosis y Enfermedades Transmitidas por Artrópodos Vectores, Hospital Universitario San Pedro - Centro de Investigación Biomédica de La Rioja (CIBIR).
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Black spot or “tache noire” in Mediterranean spotted fever. Courtesy of Elsevier [Garcia-Fernandez-Bravo I, Demelo-Rodriguez P, Alejandre de Ona A, Del Toro Cervera J. Black spot or “tache noire” in Mediterranean spotted fever. Medicina Clinica (Barc). 2018 Aug 10;151(3):130. Online at: https://www.elsevier.es/en-revista-medicina-clinica-english-edition--462-articulo-black-spot-or-tache-noire-S2387020618302328.].
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