Acknowledgments We are grateful to Stanley W. Chapman, the Wilson Research Foundation, Raoult Ratard, Andrea Vicari, Grant L. Campbell, Michael Bunning, and Susan P. Montgomery for their important contributions to this investigation. Dr. Sejvar is a neurologist and epidemiologist with the Centers for Disease Control and Prevention’s Division of Viral and Rickettsial Diseases, National Center for Infectious Diseases. His current areas of research include the epidemiology of encephalitis, prion diseases, and other infections of the nervous system. References 1. Tsai T, Popovici F, Cernescu C, Campbell G, Nedelcu N. West Nile encephalitis epidemic in southeastern Romania. Lancet 1998; 352:767–71. 2. Mostashari F, Bunning M, Kitsutani P, Singer D, Nash D, Cooper M, et al. Epidemic West Nile encephalitis, New York, 1999: results of a household-based seroepidemiological survey. Lancet 2001; 358:261–4. 3. Chowers M, Lang R, Nassar F, Giladi D, Rubinshtein E, Itzhaki A, et al. Clinical characteristics of the West Nile fever outbreak, Israel, 2000. Emerg Infect Dis 2001;7:675–8. 4. Nash D, Mostashari F, Fine A, Miller J, O’Leary D, Murray K, et al. The outbreak of West Nile virus infection in the New York City area in 1999. N Engl J Med 2001;344:1807–14. 5. Sampson B, Ambrosi C, Charlot A, Reiber K, Veress J, Armbrustmacher V, et al. The pathology of human West Nile virus infection. Hum Pathol 2000;31:527–31. 6. Asnis D, Conetta R, Teixeira A, Waldman G, Sampson B. The West Nile virus outbreak of 1999 in New York City: the Flushing Hospital experience. Clin Infect Dis 2000;30:413–8. 7. Leis A, Stokic D, Polk J, Dostrow V, Winkelmann M. A poliomyelitis-like syndrome from West Nile virus infection. N Engl J Med 2002;347:1279–80 8. Glass J, Samuels O, Rich M. Poliomyelitis due to West Nile virus. N Engl J Med 2002;347:1280–1. 9. Centers for Disease Control and Prevention. Acute flaccid paralysis syndrome associated with West Nile virus infection—Mississippi and Louisiana, July–August 2002. MMWR Morb Mortal Wkly Rep 2002;51:825–7. 10. Martin D, Muth D, Brown T, Johnson A, Karabatsos N, Roehrig J. Standardization of immunoglobulin M capture enzyme-linked immunosorbent assays for routine diagnosis of arboviral infections. J Clin Microbiol 2000;38:1823–6. 11. Beaty B, Calisher C, Shope R. Arboviruses. In: Lennette E, Lennette D, and Lennette E, editors. Diagnostic procedures for viral, rick- ettsial, and chlamydial infections. Washington: American Public Health Association; 1995. p. 89–212. 12. Prince H, Hogrefe W. Performance characteristics of an in-house assay system used to detect West Nile virus (WNV)-specific immunoglobulin M during the 2001 WNV season in the United States. Clin Diagn Lab Immunol 2003;10:66–9. 13. Martin D, Biggerstaff B, Allen B, Johnson A, Lanciotti R, Roehrig J. Use of immunoglobulin M cross-reactions in differential diagnosis of human flaviviral encephalitis infections in the United States. Clin Diagn Lab Immunol 2002;9:544–9. 14. Petersen L, Marfin A. West Nile virus: a primer for the clinician. Ann Intern Med 2002;137:173–9. 15. Kimura J. Electrodiagnosis in diseases of nerve and muscle: princi- ples and practice. 2nd ed. Philadelphia: F.A. Davis Co.; 1989. p. 249–74. 16. Kornreich L, Dagan O, Grunebaum M. MRI in acute poliomyelitis. Neuroradiology 1996;38:371–2. RESEARCH 17. Rao D, Bateman D. Hyperintensities of the anterior horn cells on MRI due to poliomyelitis. Journal of Neurology, Neurosurgery, and Psychiatry 1997;63:720. 18. Huang C, Liu C, Chang Y, Chen C, Wang S, Yeh T, et al. Neurologic complications in children with enterovirus 71 infection. N Engl J Med 1999;341:936–42. 19. Ohry A, Karpin H, Yoeli D, Lazari A, Lerman Y. West Nile virus myelitis. Spinal Cord 2001;39:662–3. 20. Rotbart H. Viral meningitis and the aseptic meningitis syndrome. In: Scheld W, Whitley R, Durack D, editors. Infections of the central nervous system. Philadelphia: Lippincot-Raven Publishers; 1997. p. 239–63. 21. Solomon T, Kneen R, Dung N, Khan V, Thuy T, Ha D, et al. Poliomyelitis-like illness due to Japanese encephalitis virus. Lancet 1998;351:1094–7. 22. Kho L, Sumarmo W, Jahja E, Gubler D. Dengue hemorrhagic fever accompanied by encephalopathy in Jakarta. Southeast Asian J Trop Med Public Health 1981;12:83–6. 23. Sumarmo W, Wulur H, Jahja E, Gubler D, Suharyono W, Sorensen K. Clinical observations on virologically confirmed fatal dengue infec- tions in Jakarta, Indonesia. Bull World Health Organ 1983;61:693–701. 24. Gadoth N, Weitzman S, Lehmann E. Acute anterior myelitis compli- cating West Nile fever. Arch Neurol 1979;36:172–3. 25. Manuelidis EE. Neuropathology of experimental West Nile virus infection in monkeys. J Neuropathol Exp Neurol 1956;15:448–60. 26. Cantile C, Di Guardo G, Eleni C, Arispici M. Clinical and neu- ropathological features of West Nile virus equine encephalomyelitis in Italy. Equine Vet J 2000;32:31–5. 27. Cantile C, Del Piero F, Di Guardo G, Arispici M. Pathologic and immunohistochemical findings in naturally occurring West Nile virus infection in horses. Vet Pathol 2001;38:414–21. 28. Steele K, Linn M, Schoepp R, Komar N, Geisber T, Manduca R, et al. Pathology of fatal West Nile virus infection in native and exotic birds during the 1999 outbreak in New York City, New York. Vet Pathol 2000;37:208–24. 29. Gorson K, Ropper A. Nonpoliovirus poliomyelitis simulating Guillain-Barré syndrome. Arch Neurol 2001;58:1460–4. 30. Asbury A, Arnason B, Karp H. Criteria for diagnosis of Guillain- Barré syndrome. Ann Neurol 1978;3:565–6. 31. Weinberg D. AAEM case report #4: Guillain-Barré syndrome. Muscle Nerve 1999;22:271–81. 32. Hurwitz E, Holman R, Nelson D, Schonberger L, Breman D, Kaslow R, et al. National surveillance for Guillain-Barré syndrome. January 1978–March 1979. Neurology 1983;33:150–7. 33. Visser L, Van der Meche F, Van Doorn P, Meulstee J, Jacobs B, Oomes P, et al. Guillain-Barré syndrome without sensory loss (acute motor neuronopathy): a subgroup with specific clinical, electrodiag- nostic, and laboratory features. Brain 1995;118:841–7. 34. Norda R, Berseus O, Stemayr B. Adverse events and problems in therapeutic hemapheresis. A report from the Swedish registry. Transfusion and Apheresis Sciences 2001;25:33–41. 35. Stangel M, Muller M, Marx P. Adverse events during treatment with high-dose intravenous immunoglobulins for neurological disorders. Eur Neurol 1998;40:173–4. 36. Gottlieb S. Intravenous immunoglobulin increases the risk of throm- botic events. BMJ 2002;324:1056. 37. Struble E, Dice Y. Intravenous immune globulin (IVIG) precipitating acute myocardial infarction. J Miss State Med Assoc 2002;43:115. Address for correspondence: James J. Sejvar, Medical Epidemiologist, Division of Viral and Rickettsial Diseases, National Center for Infectious Diseases, Centers for Disease Control and Prevention, 1600 Clifton Road, Mailstop A39, Atlanta, GA 30333, USA; fax: 404-639-3163; email: zea3@cdc.gov Emerging Infectious Diseases • Vol. 9, No. 7, July 2003 793