Theresa L' Smith, MD, MPH Division of VectorBorne Infectious Diseases Centers for Disease Control an

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Theresa L. Smith, MD, MPHDivision of
Vector-Borne Infectious DiseasesCenters for
Disease Control and PreventionFort Collins, CO

• West Nile Virus
• Epidemiology Surveillance Update 2005
• Blood Product Advisory Committee
• Gaithersburg, MDNovember 3, 2005

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West Nile Virus (WNV) Update

• Virology
• Epidemiology of WNV in US 1999 2005
• 2005 surveillance update
• Blood donation surveillance events
• Unless marked, all data including 2005 was in
  ArboNET as of 11/1/05

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WNV Virology

• Flavivirus in the Japanese encephalitis serogroup
• WNV St. Louis encephalitis in the US
• Primarily bird pathogen
• Bird mosquito bird transmission cycle
• Mammals are dead-end hosts in natural cycle
• Low-level viremia before illness onset

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WNV Update

• Virology
• Epidemiology of WNV in US 1999 2005
• 2005 surveillance update
• Blood donation surveillance events

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ArboNET A National Arbovirus Surveillance System

• Web-based passive system begun in 2000
• 57 area health departments to DVBID
• Mosquito, bird, horse, other animal surveillance
• Year, state, county, date of collection
• Human cases
• Age, sex, race/ethnicity
• Residence
• Clinical illness, onset date and outcome
• Blood or organ donation/receipt

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First Reported WNV Activity, by State, 1999-2005
1999
2002
2000
2003
2001
2004
Human
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2,539 human cases 1,142 WNND 100 deaths
40 states DC 523 counties
2004
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2,581 human cases 1,053 WNND 83 deaths
40 states 563 counties
2005
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WNV Update

• Virology
• Epidemiology of WNV in US 1999 2005
• 2005 surveillance update
• Blood donation surveillance events

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Human WNV Disease Casesby week of illness onset
and date reported to ArboNETUnited States, 2004
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Reported Human WNV disease cases,United States,
1999-2005

• Year Cases States/District
• 1999 62 1
• 2000 21 3
• 2001 66 10
• 2002 4,156 39 DC
• 2003 9,862 45 DC
• 2004 2,539 40 DC
• 2005 2,581 42

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Human WNV Disease, ArboNET 2005

• 2,581 case reports
• 42 states
• Neuroinvasive 1,053
• Fever 1,363
• Deaths 83
• Median age 78 yrs
• Age range 36 98 yrs

• States with gt 100 case reports
• California 824
• Illinois 241
• South Dakota 235
• Texas 139
• Louisiana 111
• Arizona 102
• 64 of all reports

78 fatalities had age available
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WNV Update

• Virology
• Epidemiology of WNV in US 1999 2005
• 2005 surveillance update
• Blood donation surveillance events

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WNV Blood Screening, US, 2003-2005

• Year Screened PVDs WNND WNF TAT
• 2003 6.2 818 6 137 6
• 2004 8.2 224 4 66 1
• 2005 NA 374 3 82 1
• In millions

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Data unavailable
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Reported PVDs to ArboNET, 2004 vs. 2005

• 2004
• 224 in 29 states
• Top four states
• California 66
• Arizona 36
• Colorado 24
• Texas 16

• 2005
• 374 in 30 states
• Top four states
• California 87
• Texas 57
• Nebraska 53
• Louisiana 22

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Implicated Donation Viral Concentrations

• 2002
• 16 implicated donations had virus titers ranging
  from 0.8 to 75.1 pfu/mL with a of median of 10.5
  pfu/mL
• 2003
• Four implicated donations had virus titers
  ranging from 0.06 to 0.5 pfu/mL with a median of
  0.11 pfu/mL
• 2004
• One implicated donation had a viral titer of 0.12
  pfu/mL

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2005 Investigations

• Blood Transmission
• 6 investigations
• 3 negative
• 3 pending plasma return from Switzerland
• Organ Transplantation Transmission
• Likely mosquito-borne infection in donor
• Possible febrile illness
• IgM positive, PCR negative before donation
• Three of four organ recipients PCR positive
• Two became ill

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Organ Donor TimelineAugust 2005
WNV Mosquitoes In Nearby Park
Injury and Surgery
Organ Recovery
BrainDeath
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26
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16
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Serum, Plasma PCR (-) IgM, IgG ()
Febrile Illness?
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2005 Summary

• WNV activity over most of the continental US
• Continued westward expansion
• Full season of transmission in CA
• Human cases reported from all states except
  Alaska, Hawaii, Maine, Washington
• Risk of WNV TAT unknown
• Continue to investigate possible TAT
• TAT less likely to cause organ transplant related
  WNV transmission