West Nile Virus Encephalitis, Rickettsial Disease, and Syphilis/St. Louis Encephalitis: Triple Coinfection or Serologic Cross-Reactivity? A Case SeriesAkhondi Asl, Hossein MD*; Smith, Margo MD†Infectious Diseases in Clinical Practice: May 2013 - Volume 21 - Issue 3 - p e10–e12 doi: 10.1097/IPC.0b013e31827692a7 Case Reports Abstract Author Information Abstract: Infections of the central nervous system that are caused by more than one organism are on the rise. Dual or triple infections are diagnosed more commonly, and new tests are being developed to target this matter and diagnose multiple coinfection simultaneously. We present 2 cases of West Nile virus encephalitis, both with a concomitant rickettsial disease (typhus and ehrlichiosis) as well as syphilis in one case and positive serology for St. Louis encephalitis in another. Cross-reactivity with West Nile virus was thought to be the reason for the positivity of the St. Louis virus; but for the other tests, it was felt that they were true positive, as suggested by clinical findings. Suspicion for these coinfections can help with better diagnosis and management and hopefully reduce morbidity and mortality. From the *Washington Hospital Center, Washington, DC and †Infectious Disease Department, Washington Hospital Center, Washington, DC. Correspondence to: Hossein Akhondi Asl, MD, Washington Hospital Center, Washington, DC. E-mail: firstname.lastname@example.org. The authors have no funding or conflicts of interest to disclose. © 2013 by Lippincott Williams & Wilkins.