WEST NILE VIRUS INFECTION 2004 WESTWARD MIGRATION Laurene Mascola, MD, MPH, FAAP Chief, Acute Communicable Disease Control Program County of Los Angeles Department of Health Services UCLA Grand Rounds July 2, 2004 Contributor: Rachel Civen, MD, MPH and Carol Ann Glaser, DVM, et al. DHS D16:\WNV_UCLA July 2_2004.ppt No. 1 Acute Communicable Disease Control OUTLINE West Nile Virus Overview (cid:102) West Nile Virus Outbreaks and entry to (cid:102) U.S. 1999 Surveillance (cid:102) Epidemiology and Clinical Presentation (cid:102) Diagnosis (cid:102) New Modes of Transmission (cid:102) Prevention (cid:102) DHS Acute Communicable Disease Control Unit D16:\WNV_UCLA July 2_2004.ppt No. 2 ARTHROPOD-BORNE ENCEPHALITIS (1) Agents: Eastern equine, Western (cid:102) equine, St. Louis, La Crosse, California, West Nile viruses Incubation: 2-15 days (cid:102) Reservoir: Unknown, probably wild (cid:102) birds Transmission: Bite of infective mosquitoes (cid:102) DHS Acute Communicable Disease Control Unit D16:\WNV_UCLA July 2_2004.ppt No. 3 ARTHROPOD-BORNE ENCEPHALITIS (2) Presentation: Ranges from (cid:102) asymptomatic to aseptic meningitis to encephalitis Diagnosis: Serologic tests (cid:102) Treatment: Supportive (cid:102) Prevention: Mosquito avoidance, (cid:102) Mosquito abatement DHS Acute Communicable Disease Control Unit D16:\WNV_UCLA July 2_2004.ppt No. 4 WEST NILE VIRUS Single-stranded RNA enveloped virus (cid:102) of the familily Flaviviridae, genus Flavivirus Japanese encephalitis virus (cid:102) (cid:57)West Nile virus (WNV) (cid:57)Saint Louis encephalitis virus (cid:57)Japanese Equine encephalitis virus (cid:57)Murray Valley virus complex (cid:57)Kinjin virus DHS Acute Communicable Disease Control Unit D16:\WNV_UCLA July 2_2004.ppt No. 5 BACKGROUND: WNV INFECTIONS (1) 1937: First isolated in West Nile district (cid:102) of Uganda 1957: Israeli nursing home outbreak (cid:102) (cid:57)Associated with severe neurologic disease and higher mortality rate 1990s: Frequency and severity of WNV (cid:102) outbreaks increased DHS Acute Communicable Disease Control Unit D16:\WNV_UCLA July 2_2004.ppt No. 6 BACKGROUND: WNV INFECTIONS (2) Outbreaks in: (cid:102) (cid:57)1994 Algeria (cid:57)1996 Romania: associated with severe neurologic illness (cid:57)1997 Czech Republic (cid:57)1998 Italy (cid:57)1999 Russia: associated with severe neurologic illness (cid:57)1999 USA: entry into US/NY outbreak DHS Acute Communicable Disease Control Unit D16:\WNV_UCLA July 2_2004.ppt No. 7 WEST NILE FEVER: BACKGROUND AND EPIDEMIOLOGY (1) Worldwide distribution (cid:102) Enzootic many parts of the world: (cid:102) Africa, Middle East, West Asia, Australia Caused primarily outbreaks of (cid:102) febrile illnesses: soldiers, children, and healthy adults DHS Acute Communicable Disease Control Unit D16:\WNV_UCLA July 2_2004.ppt No. 8 WEST NILE FEVER: BACKGROUND AND EPIDEMIOLOGY (2) Commonly found in humans and birds (cid:102) and other vertebrates Basic transmission cycle involves (cid:102) mosquitoes feeding on birds infected with the West Nile Virus Infected mosquitoes then transmit (cid:102) West Nile Virus to humans and animals when taking a blood meal DHS Acute Communicable Disease Control Unit D16:\WNV_UCLA July 2_2004.ppt No. 9 WEST NILE VIRUS (WNV) TRANSMISSION CYCLE Mosquito Vector Incidental Infections West Nile Incidental Infections Virus Bird Reservoir Hosts DHS Acute Communicable Disease Control Unit D16:\WNV_UCLA July 2_2004.ppt No. 10