Rickettsia rickettsii encephalitis in Brazilian spotted fever: a case report.
5 affiliations
- 1Graduate Program in Molecular Medicine, Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, Brazil. [email protected].
- 2Centro de Tecnologia em Medicina Molecular (CTMM), Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, Brazil. [email protected].
- 3Department of Neurology, Hospital das Clínicas da UFMG, Belo Horizonte, Brazil.
- 4Graduate Program in Medicine/Biomedicine, Faculdade Santa Casa de Belo Horizonte, Belo Horizonte, Minas Gerais, Brazil.
- 5Department of Internal Medicine, Faculdade de Medicina da UFMG, Belo Horizonte, Brazil.
Abstract
Brazilian spotted fever, caused by Rickettsia rickettsii, is a life-threatening tick-borne disease endemic to southeastern Brazil and is associated with high mortality when treatment is delayed. Central nervous system involvement poses a particular diagnostic challenge because of nonspecific early symptoms and frequent misdiagnosis as dengue or leptospirosis. We report a case illustrating characteristic neuroimaging findings and therapeutic considerations in rickettsial encephalitis. We describe the clinical course, cerebrospinal fluid (CSF) findings, magnetic resonance imaging (MRI) findings, serologic results, and treatment response in a 23-year-old man who presented with febrile encephalopathy in an endemic region of Brazil. The patient had a five-day history of fever, erythematous macules, and progressive encephalopathy. CSF analysis showed elevated protein and lymphocytic pleocytosis. MRI showed T2/fluid-attenuated inversion recovery hyperintensities with restricted diffusion involving the bilateral corticospinal tracts and the splenium of the corpus callosum, forming a "boomerang" pattern. Clinical improvement followed initiation of empirical doxycycline and pulse methylprednisolone. Serologic testing supported the diagnosis of R. rickettsii infection with a positive immunoglobulin M titer of 1:512. Follow-up MRI showed near-complete lesion resolution at 4 months, with a residual splenial lesion persisting at 18 months. This case illustrates the importance of recognizing characteristic MRI patterns, including the "starry sky" and "boomerang" signs, as diagnostic clues in rickettsial encephalitis, even when the classic triad is incomplete. Early empirical doxycycline remains critical for neurologic outcomes, and adjunctive corticosteroids may have a role in selected cases when immune-mediated central nervous system injury is suspected.
Related
- Molecular evidence of spotted fever group Rickettsia and Lyme disease– and relapsing fever–associated Borrelia, and the absence of scrub typhus-associated Orientia in ixodid ticks from contrasting habitats in Peninsular Malaysia
- Spotted fever group Rickettsia infection kinetics and cutaneous host response during single tick feeding events
- Molecular detection of Rickettsia spp. in ticks (Ixodida: Argasidae and Ixodidae) and mites (Trombiculoidae) from a Brazilian taxonomic collection.
- Case Report: Late postpartum eclampsia-associated reversible posterior encephalopathy syndrome with anti-DPPX encephalitis
- Autochthonous tick-borne lymphadenopathy (TIBOLA) in a 3-year-old child caused by Rickettsia slovaca in southwestern Germany
BibTeX
@article{brunheroto2026rickettsia,
title = {{Rickettsia rickettsii encephalitis in Brazilian spotted fever: a case report.}},
author = {Felipe B Brunheroto and Eduardo Roquim E Silva and Raquel Araujo and Paulo Christo},
journal = {Encephalitis (Seoul, Korea)},
year = {2026},
month = oct,
doi = {10.47936/encephalitis.2026.00073},
url = {https://europepmc.org/article/MED/42843902},
note = {CC BY-NC},
}
RIS
TY - JOUR
TI - Rickettsia rickettsii encephalitis in Brazilian spotted fever: a case report.
AU - Felipe B Brunheroto
AU - Eduardo Roquim E Silva
AU - Raquel Araujo
AU - Paulo Christo
PY - 2026
DA - 2026/10/08
JO - Encephalitis (Seoul, Korea)
DO - 10.47936/encephalitis.2026.00073
UR - https://europepmc.org/article/MED/42843902
AB - Brazilian spotted fever, caused by Rickettsia rickettsii, is a life-threatening tick-borne disease endemic to southeastern Brazil and is associated with high mortality when treatment is delayed. Central nervous system involvement poses a particular diagnostic challenge because of nonspecific early symptoms and frequent misdiagnosis as dengue or leptospirosis. We report a case illustrating characteristic neuroimaging findings and therapeutic considerations in rickettsial encephalitis. We describe the clinical course, cerebrospinal fluid (CSF) findings, magnetic resonance imaging (MRI) findings, serologic results, and treatment response in a 23-year-old man who presented with febrile encephalopathy in an endemic region of Brazil. The patient had a five-day history of fever, erythematous macules, and progressive encephalopathy. CSF analysis showed elevated protein and lymphocytic pleocytosis. MRI showed T2/fluid-attenuated inversion recovery hyperintensities with restricted diffusion involving the bilateral corticospinal tracts and the splenium of the corpus callosum, forming a "boomerang" pattern. Clinical improvement followed initiation of empirical doxycycline and pulse methylprednisolone. Serologic testing supported the diagnosis of R. rickettsii infection with a positive immunoglobulin M titer of 1:512. Follow-up MRI showed near-complete lesion resolution at 4 months, with a residual splenial lesion persisting at 18 months. This case illustrates the importance of recognizing characteristic MRI patterns, including the "starry sky" and "boomerang" signs, as diagnostic clues in rickettsial encephalitis, even when the classic triad is incomplete. Early empirical doxycycline remains critical for neurologic outcomes, and adjunctive corticosteroids may have a role in selected cases when immune-mediated central nervous system injury is suspected.
SN - 2765-4559
SN - 2734-1461
ER -