Imaging of rickettsial, spirochetal, and parasitic infections.

This article reviews the clinical signs, symptoms, and neuroimaging findings of the commonly known rickettsial, spirochetal, and parasitic infections (cysticercosis is covered elsewhere in this issue). Differential diagnoses and significant imaging characteristics are reviewed to help narrow the diagnostic possibilities. Several of the infections in this disparate group are not seen as commonly as they once were because of advances in early diagnosis, treatment, improvements in sanitation, and prevention of epidemics. Many of the infections, however, are endemic to certain parts of the world and are seen with increasing frequency in immunocompromised individuals.