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Transcript of Black Bugs Blood: West Nile Virus & the Blood Supply Infectious Transfusion Risks, Screening Blood...
Black Bugs Blood:West 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
Risks of Transmission
• Infectious Risks– Viral
– Bacterial
– Protozoa
– Ricketsia
– Other• ?Prion
• Non-infectious risks– Transfusion Reaction
– Metabolic
– Cardiac Overload
– Dilutional Coagulopathy
– TAGVHD
– Alloimmunization
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
101102103104 100105106107108
HIV
HCVHBV
Mis-Transfusion
TRALI
TA-GVHD
Under transfusion
Cardiac
Paling Risk Scale for Major Transfusion Hazards
Metabolic risk in neonates
Bacteria
General anesthesia
Sunny Dzik, MD
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.
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
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.
U.S. NAT Program Yields
Program # HCVRate
# HIVRate
UBS
ABC-Roche
AIBC
ARC
US Total
16
23
2
29
70
1:294,926
1:239,630
1:236,937
1:331,828
1:275,830
2
1
0
1
4
1:2,359,409
1:2,581,512
0:473,874
1:9,623,012
1:3,759,451
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
Cost/HCV-NAT positive donation:
• Average HCV-NAT pos. rate in US = 1:276,000 donations
• 13 million donations/yr collected
• 47 window case donations expected @ $104,000,000 total
• Cost/HCV-NAT positive donation detected = $>2,200,000/donation
Cost/HIV-NAT positive donation:
• Average HIV-NAT pos. rate in US = 1:3,760,000 donations
• 13 million donations/yr collected
• 3.5 window case donations expected @ $104,000,000 total
• Cost/HIV-NAT positive donation detected = > $28,000,000/donation
200,000
Cost-effectiveness ($/YLE)
600,000
400,000
2,000,000
4,000,000
6,000,000
8,000,000
ALTTesting
p24 AgTesting
Anti-HBcTestingfor HIV
MP NATHIV+HCV
SD FPHCVLook-back
RhIg/HDN Prophy-
laxis
CABG(one
vessel)
HTN
Therapy
AnnualMammo-
gram
CardiacTrans-
plantation
Transfusion Safety Interventions
Commonly Accepted Medical Practices
PAD- CABG
MP=>SDNAT
Cost-Effectiveness Comparisons
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
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
West Nile Virus: Background and Ecology
The Japanese Encephalitis Serocomplexof the Family Flaviviridae
1999 - 2002 Verified WNV Surveillance Results Reported to ArboNet
731919733266/927 + DC2001
44 + DC
11 + DC
4
States
11,450
63
25
Horses
593814,7903949/262 2002
515430521/22000
16?62/61999
MosquitoPools
BirdsHumans/Fatalities
Year
Date of Symptom Onset, West Nile VirusUnited States, 1999-2001
0
5
10
15
20
25
30
7/7
8/4
9/1
9/29
10/2
711
/24
12/2
3
Week ending
Nu
mb
er
of
ca
se
s
2001
2000
1999
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
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%
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
More Automated System
COBAS AmpliPrep
COBAS TaqMan (96/48)
Hamilton Pipettor
WNV Human cases and deaths
State Cases Deaths Colorado 2647 61 Nebraska 1942 29 South Dakota 1039 14 Texas 717 37 North Dakota 617 5 Wyoming 375 9 Pennsylvania 237 8 Total 9862 264
+ WNV rate weekly (6/30-9/30)WNV Incidence
0.000%
0.100%
0.200%
0.300%
0.400%
0.500%
0.600%
0.700%
0.800%
1 2 3 4 5 6 7 8 9 10 11 12 13
Week
% P
osi
tive CBBLAN
MBC
Siouxland
SFSV+Avera
1 / 500
2004 map as of 10/26/04
2004 counties 10/26/04
WNV+ blood donors - 10/26/04
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.
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