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Black Bugs Blood: West Nile Virus

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West Nile Virus ... mosquitoes then transmit West Nile virus to humans and ... Outcome of West Nile Virus Infection among Hospitalized Patients. At ... – PowerPoint PPT presentation

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Title: Black Bugs Blood: West Nile Virus


1
Black Bugs BloodWest Nile Virus the Blood
Supply
  • Infectious Transfusion Risks, Screening Blood
    donations for WNV and other icky things
  • Jed Gorlin, Memorial Blood Centers Duluth TAM
    11/04

2
Risks of Transmission
  • Infectious Risks
  • Viral
  • Bacterial
  • Protozoa
  • Ricketsia
  • Other
  • ?Prion
  • Non-infectious risks
  • Transfusion Reaction
  • Metabolic
  • Cardiac Overload
  • Dilutional Coagulopathy
  • TAGVHD
  • Alloimmunization

3
Transfusion Safety
  • Product Safety
  • Donor Recruitment
  • Donor history screening
  • Donor Testing
  • Manufacturing cGMP
  • Transfusion Safety
  • Patient blood sample
  • Med indication for Tx.
  • Special Tx needs
  • Select right unit
  • Issue to floor
  • administration
  • monitoring evaluation of reaction

4
Paling Risk Scale for Major Transfusion Hazards
101
102
103
104
100
105
106
107
108
HIV
General anesthesia
HCV
HBV
Bacteria
Mis-Transfusion
TRALI
TA-GVHD
Cardiac
Metabolic risk in neonates
Under transfusion
Sunny Dzik, MD
5
Window period risk
  • Why is there any residual risk? There is
    potential for transfusion transmission, if donors
    is drawn after acquiring the disease but before
    they make an antibody response.
  • Time from infectivity to test reactivity
  • Chance of transmission is a function of both
    incidence and length of window period.

6
NAT screening (HCV/HIV/HBV)
  • Two major testing platforms for HIV/HCV
  • Roche-Pools of 24, separate tests for HCV, HIV.
    Advantage automated detection, disadvantage,
    very manual sample prep
  • Chiron-Gen Probe (TMA) Multiplex test
  • Pools of 16, automated sample prep, manual
    detection. Requires extra round to resolve
    positive samples. More false positives

7
MBC Experience
  • After testing almost 2,000,000 samples, MBC has
    detected 1 HIV NAT window period case and 5 HCV
    NAT/EIA negative samples.
  • Almost 1,000,000 samples were tested for both HCV
    and HIV before a single NAT/EIA - sample was
    found.

8
U.S. NAT Program Yields
9
What Has NAT Testing Cost the US??
  • Assume 13 million blood donations annually
  • Assume an average cost/donation of 16
  • Cost of HCV/HIV- NAT
  • 208,000,000/yr or 104M each

10
Cost/HCV-NAT positive donation
  • Average HCV-NAT pos. rate in US 1276,000
    donations
  • 13 million donations/yr collected
  • 47 window case donations expected _at_ 104,000,000
    total
  • Cost/HCV-NAT positive donation detected
    gt2,200,000/donation

11
Cost/HIV-NAT positive donation
  • Average HIV-NAT pos. rate in US 13,760,000
    donations
  • 13 million donations/yr collected
  • 3.5 window case donations expected _at_
    104,000,000 total
  • Cost/HIV-NAT positive donation detected gt
    28,000,000/donation

12
Cost-Effectiveness Comparisons
Cost-effectiveness


(/YLE)
8,000,000
6,000,000
Transfusion Safety Interventions
4,000,000
2,000,000
600,000
400,000
200,000
Commonly Accepted Medical Practices
ALT Testing
p24 Ag Testing


RhIg/HDN

CABG (one vessel)

HTN

Annual Mammo- gram
Cardiac Trans- plantation
PAD-


SD FP
HCV Look- back

Anti-HBc Testing for HIV
MP NAT HIVHCV



MPgtSD NAT
Prophy-

CABG

Therapy
laxis
13
Other Transfusable Parasitic
  • Chagas
  • Trypanosoma cruzi Endemic Central So. America
  • Infected reduviid (kissing) bug falls from
    thatched roof, defecates and inoculates skin
  • May be under-recognized cause of heart failure
  • Only 7 cases Tx transmission in US/Canada
  • Screened for in Brazil and other LA countries
  • ARC proposes to implement screening
  • MBC to participate in Chagas trial 1/05

14
West Nile Virus Background and Ecology
West Nile Virus Background and Ecology
  • First isolated in West Nile district, Uganda,
    1937
  • Commonly found in humans and birds and other
    vertebrates in Africa, Eastern Europe, West Asia,
    and the Middle East, but has not previously been
    documented in the Western Hemisphere
  • Basic transmission cycle involves mosquitoes
    feeding on birds infected with the West Nile
    virus
  • Infected mosquitoes then transmit West Nile virus
    to humans and animals when taking a blood meal

15
The Japanese Encephalitis Serocomplexof the
Family Flaviviridae
16
1999 - 2002 Verified WNV Surveillance Results
Reported to ArboNet
17
Date of Symptom Onset, West Nile VirusUnited
States, 1999-2001
18
Clinical Epidemiology
  • Incubation period 3 - 14 days
  • 80 of infections are asymptomatic
  • 20 develop West Nile fever
  • 1 in 150 develop meningoencephalitis
  • Advanced age primary risk factor for severe
    neurological disease and death

19
Outcome of West Nile Virus Infection among
Hospitalized Patients
  • At discharge (NY and NJ, 2000)
  • More than half did not return to functional level
  • Only one-third fully ambulatory
  • At one year (NYC 1999 patients)
  • Fatigue 67, memory loss 50, difficulty walking
    49, muscle weakness 44, depression 38

20
Summer 2003
  • Implemented WNV NAT screening 7/1/03
  • Automated DNA extraction
  • Pool size 6-dedicated pooling machines
  • TaqMan platform requires lots of room. Total NAT
    laboratory space doubled
  • MBC detected 36 WNV blood donors, mostly in
    Nebraska, South Dakota and Iowa

21
More Automated System
COBAS TaqMan (96/48)
Hamilton Pipettor
COBAS AmpliPrep
22
(No Transcript)
23
WNV Human cases and deaths
24
WNV rate weekly (6/30-9/30)
25
2004 map as of 10/26/04
26
2004 counties 10/26/04
27
WNV blood donors - 10/26/04
28
2004 WNV Transfusion transmission in Arizona
  • MMWR Sept 17, 2004 p 842
  • In 2003 blood centers interdicted 800 blood
    components via pooled testing. Because of 6 cases
    of transfusion transmission, a policy for single
    donor (SD) testing was implemented for 2004.
  • 3 days before switch to SD in Arizona (from TMA
    pool of 16), a 43 yo with severe diabetes was
    transfused following a knee amputation. He
    subsequently developed WNV and died. The units
    were traced and one donor was shown to be WNV by
    SD but not pooled testing.

29
Implications
  • Despite reduced pool size and plans to implement
    single donor testing, window period cases of WNV
    continue to occur.
  • There have been two HIV transmissions despite
    pooled NAT testing
  • Both manufacturers are working to create more
    automated systems that facilitate single donor
    testing. These will be more expensive, but will
    allow greater throughput than current manual tests
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