Update on West Nile Virus

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Update on West Nile Virus United States,
1999-2006
Blood Products Advisory Committee 89th
Meeting April 27, 2007

• Eileen C. Farnon, MD
• Arboviral Diseases Branch
• Division of Vector-Borne Infectious Diseases
• Centers for Disease Control and Prevention
• Fort Collins, Colorado

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WNV Transmission Cycle
Enzootic (Maintenance/Amplification)
Amplifying hosts
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(No Transcript)
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ArboNET

• Arboviral national electronic surveillance system
• Humans
• Ecologic
• Mosquitoes
• Birds
• Animals
• WNV, SLE, EEE, WEE, LAC, DEN, VEE
• All data current as of April 12, 2007

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Human WNV Syndromes Reported to ArboNET

• WN fever (WNF)
• WN neuroinvasive disease (WNND)
• Meningitis
• Encephalitis
• Acute flaccid paralysis
• Other
• Unspecified illness

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WNV Neuroinvasive Disease Incidence, by County,
US, 1999
N59
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WNV Neuroinvasive Disease Incidence, by County,
US, 2000
N19
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WNV Neuroinvasive Disease Incidence, by County,
US, 2001
N64
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WNV Neuroinvasive Disease Incidence, by County,
US, 2002
N2,946
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WNV Neuroinvasive Disease Incidence, by County,
US, 2003
N2,866
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WNV Neuroinvasive Disease Incidence, by County,
US, 2004
N1,148
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WNV Neuroinvasive Disease Incidence, by County,
US, 2005
N1,309
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WNV Neuroinvasive Disease Incidence, by County,
US, 2006
N1,491
Reported as of 4/12/2007
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Onset of Human WNV Disease, United States
1999-2006
Reported as of 4/12/2006
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Cumulative WNND Incidence, by County, US,
2002-2006
Reported as of 11/14/06 Lindsey N, et al, in
press
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Median Annual WNND Incidence Rank versus
Cumulative WNND Incidence Rank by County,
2002-2006
Reported as of 11/14/06 Lindsey N, et al, in
press
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Counties with Persistently High WNND Incidence,
2002-2006
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Reported WNV Disease Cases in Humans United
States, 1999-2006
Year Total WNND WNF/other Deaths
1999-2001 149 142 7 18
2002 4,156 2,946 1,210 284
2003 9,862 2,866 6,996 264
2004 2,539 1,148 1,391 100
2005 3,000 1,309 1,691 119
2006 4,261 1,491 2,770 176
Total 23,967 9,902 14,065 961
Reported as of 4/12/2007
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WNV Blood Screening

• 2002 23 cases of transfusion-associated
  transmission (TAT)
• 2003 Nucleic acid amplification tests (NAT)
• MP-NAT (6-16 units) ? ID-NAT
• Blood banks report presumptively viremic donors
  (PVDs) to local public health department
• Remove infectious blood products from circulation
• Public health departments report to ArboNET
• Perform clinical follow-up
• Perform trace-back investigations

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WNV PVDs by Year
Year PVDs
2003 818
2004 224
2005 417
2006 361
Total 1820
Reported as of 4/12/2007
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West Nile Viremic Blood Donors, by State of
Residence, 2006
Reported as of 4/12/2007
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PVDs Reported to ArboNET, 2006

• Over 8 million donations screened
• 361 PVDs reported to ArboNET
• 84 (23) WNF
• 4 (0.1) WNND
• 2 (0.1) other
• 118 (33) reported from 3 states NE, ID, TX

Reported as of 4/12/2007
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WNV Transfusion-associated Transmission, 2006
Case 1

• 82 y male resident of SD recently post-kidney
  transplant
• 4d post-transplant 2U PRBC
• 21d post-transplant encephalitis
• WNV IgM detected in serum and CSF
• Organ donor tested negative for WNV
• Blood donor tested positive for WNV IgM
• negative MP-NAT

MMWR 2/2/07
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WNV Transfusion-associated Transmission, 2006
Case 2

• 60 y male resident of IA 5y post-kidney
  transplant
• Spinal fracture repair in SD 15 blood products
• 6U FFP from blood donor
• 11d post-operatively encephalomyelitis
• WNV IgM detected in CSF

MMWR 2/2/07
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Summary

• WNV occurs throughout the continental U.S.
• Western plains have highest incidence of WNND
• Dates of onset for WNV disease span the year
• 2 cases of transfusion-associated transmission
  despite MP-NAT testing
• New approaches to triggering ID-NAT considered

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Acknowledgements

• Jennifer Lehman
• Nicole Lindsey
• Stephanie Kuhn
• Margaret Collins
• Kate Ellingson
• Matt Kuehnert
• Mark Duffy
• Marc Fischer
• Edward Hayes
• John Jones
• Nicholas Komar

• Roger Nasci
• John Roehrig
• Janet McAllister
• Harry Savage
• James Sejvar
• Theresa Smith
• Grant Campbell
• Brad Biggerstaff
• Lyle Petersen
• All reporting states, jurisdictions, and local
  health departments

The findings and conclusions in this presentation
are those of the authors and do not necessarily
represent the views of the Centers for Disease
Control and Prevention.
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Photo Meggan Gould
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Cumulative Incidence of WNND by State United
States, 2002-2006
Reported as of 11/14/06