West Nile Virus
Transfusion Medicine Residents
Nov.30, 2007
Margaret Fearon
First Case of West Nile infection in
Canada
• 75 yr old man visits relatives in Queen’s,
New York, Sept. 1 - 5, 1999
• Returns to Toronto and is seen by GP for
myalgia and ‘heartburn
• Seen in Emerg on Sept. 10 with fever,
myalgia, diarrhea, headache and
confusion
• Lapsed into coma on Sept. 11
West Nile Encephalitis: Toronto Case
(cont.)
• CSF exam typical for viral meningoencephalitis (^protein, ^WBC, n. gluc.,neg.
gram)
• Serology at Toronto PHL (haemagglutination
inhibition)
– Sept. 13 SLE <1:10
– Sept. 18 SLE 1:40
– Sept. 25 SLE 1:350
– Confirmed as WNV specific Ab. by CDC
West Nile Encephalitis: Toronto Case
(cont.)
• Required mechanical ventilation Sept. 15
• Developed nosocomial pneumonia
• Treated with Clinda/Ceftriax., Acyclovir,
IVIG
• Died Sept. 25, 1999
Organ Donation Transmission of WNV
– 1st case
Iwamoto M et al. NEJM 2003;348:2196-2203
1st reported case of WNV transmission by organ donation
August 2002
• Organ donor from Georgia (epizootic WNV)
– Trauma July 30, 2002
– Received 63 blood components
– Declared brain dead July 31  organs recovered
August 1
– No WNV pre/post transfusion, but PCR + at time of
organ recovery
Organ Donation Transmission of WNV
– 1st case
Iwamoto M et al. NEJM 2003;348:2196-2203
2 recipients of cadaveric kidneys from same
donor in Georgia develop headache and fever 
WNV encephalitis  1 died
2 recipients of heart and liver from same donor
in Florida develop febrile illness  1 with
encephalitis
Transfusion Transmission Cases
of WNV in U.S, 2002
Pealer L.,et al. NEJM 2003;349;13 1236-1245
• 23 patients confirmed to have acquired WNV
infection via RBCs, platelets, FFP
– 15 identified by development of WNV illness (13 meningoencephalitis, 2 – fever)
– 7 received co-components
– 1 post-donation notification by donor
– Incubation 2 - 21 days
– 7 deaths
Transfusion Transmission
Cases of WNV in U.S, 2002
• 16 donors
– Found to have evidence of viremia at time of donation
(PCR) retrospectively (low viral load <80 pfu/mL)
– All IgM negative at time of donation
– 9 symptomatic before or after donation
Transfusion Transmission of WNV in
Canada 2002
414 cases of reported probable or confirmed WNV (majority
in Ontario)
5 cases of reported WNV had received blood transfusion
within 28 days:
Total 4 probable cases of TT-WNV
• 2 cases - 1 platelet, and companion (RBC) component from
an antibody positive donor
• 2 cases with multiple transfusions (60 – 100), 1 with organ
transplant with no other risk factor (antibody positive donors
not located)
• 5th case – all donors tested and no antibody positive donor
located
Public Health Agency of Canada WNV Human Cases – Surveillance Maps*
2002
414 cases
*Pink – endemic cases
Yellow – travel related cases
2003
1481 cases
2005
225 cases
2006
151 cases
2007
2335 cases
CBS preparations for 2003
• Inventory management
– Withdrew frozen plasma collected in Ontario prior to October 31,
2002
– Stockpiled red cells and frozen plasma prior to 2003 WNV season
• Donor questionnaire
– Added question about fever and headache in week prior to donation
(U.S. and Canada)
• Fast-tracked development of NAT assays (U.S., Canada)
– Roche TaqScreen WNV Assay (mini-pools of 6)
– Chiron Procleix WNV Assay (mini-pools of 16)
– CBS tested all collected units as of July 2, 2003
• (used an in house assay June 17-July 2, 2003)
CBS WNV NAT
• Roche TaqScreen WNV Assay
– Qualitative Real Time PCR
– Automated specimen prep. (COBAS AmpliPrep)
– Automated amplification & detection (COBAS TaqMan
Analyzer)
– Minipools of 6
– Reactive with all flaviviruses in Japanese encephalitis
group
– Reported sensitivity*
• 95% LOD 77.7 – 36.8 c/mL
*After 2004 modification of elution buffer and positive control
Supplemental WNV Testing
WNV NAT repeat reactives sent to National
Testing Lab (NTL) in Ottawa for:
1) Alternate NAT - Chiron (Gen Probe) Procleix WNV
Assay
– Qualitative Transcription Mediated Amplification
format
– Minipool of 16 (we run in single unit for this purpose)
– Specific for West Nile Virus
2) Serology
– PanBio- ELISA – IgM and IgG
Transfusion Transmission Cases of
WNV in North America, 2003
• 914 presumptive viremic donors identified
in U.S.,
• 14 presumptive viremic donors in Canada
• 5 cases of transfusion transmission
reported in U.S. (0 in Canada)
– Cases occurred in donors with viral load too
low to be detected in MP.
WNV Donor Testing after 2003
• After 2003 it was recognized that low viral
load viremic donors could only be
identified by single unit testing (SUT)
rather than mini-pool.
• Testing all donors (CBS tests
approximately 1 million donors/yr.)
would not be feasible or cost-effective.
• A strategy for selected SUT had to be
devised.
SUT in 2004
• The Plan
– Use the detection of a positive donor (by mini-pool
testing) to trigger SUT for clinics in that health region.
– Use a population trigger to initiate SUT in those areas
where regular donor clinics are not held.
• The Reality
– CBS given an arbitrary start date in the absence of
positive donors or reported human cases - used
positive birds as a trigger for SUT in health regions.
Strategy for Single Unit Testing
2005 - 2007
SUT initiated in a health region when one WNV positive donor is
identified,
or
The number of new confirmed community cases reported in a health
region reaches the level of 1/1,000 (rural areas) or 1/2,500 (urban)
for the past 2 consecutive weeks.
SUT discontinued if no more positive donors or # of community cases
fall below population trigger
2005 - SUT discontinued after 14 days
2006 – 2007 SUT discontinued after 7 days
*Stockpiling of frozen plasma and RBCs discontinued in 2005
Clinics for Single Unit Testing
• The clinics selected for single unit
testing are decided on a weekly
basis and/or within 24 hours when a
new WNV positive donor is identified.
• Selected clinics are located:
– Within the public health district where
the donor lives, donated, + any clinics in
close proximity in neighbouring health
regions
Identification of Samples
• High tech solution
– Manufacturing will put red
stripe on lower label of NAT
EDTA tubes with industrial
“Sharpie” pen
CBS Blood Donor Clinics
Map Key
Green – No WNV activity
Blue – Non-human cases
Yellow – Prob.or Conf.
Human Cases
Orange - >1 MP pos.donor
Red – Prob.or Conf.
Human Cases
>1/1,000 (rural)
>1/2,500 (urban)
CBS Blood Donor Clinics
Donor Follow-up
• Donors contacted by Centre M.D.
• Advised to visit family practitioner
– Further testing through local PHL
• Permission for further (NAT and antibody)
testing by CBS
• Questioned re any symptoms
• Defer for 56 days from date of reactive test
• If donor develops WNV after donation, recall
donations made in past 56 days
WNV testing at CBS*
Year
#Positive
Donors
# Pos. by SUT
Province
2003
14
2
2004
0
-
2005
15
(2 false pos.)
6
Ont. 8, Sask. 3
Man. 3, Alta.1
2006
8
4
Man. 5, Alta. 2,
Sask. 1
2007
70
(4 false. Pos.)
48
Sask. 40, Man. 21,
Alta. 4, BC/Yuk. 3,
Ont. 2
*No cases of transfusion transmission reported in Canada
since implementation of WNV testing
Sask. 10, Alta. 3,
Man. 1
-
West Nile Virus Transmission Through Blood Transfusion --- South
Dakota, 2006
MMWR Weekly February 2, 2007 / 56(04);76-79
This report describes two cases of probable transfusion-transmitted WNV
from a common blood donor despite a negative MP-NAT result at the time of
donation. The source of infection cannot be proven because blood samples
or co-components from the implicated donation were unavailable for testing;
however, evidence of WNND in two recipients of blood products from a
common donor with serologic evidence of recent infection makes WNV
transfusion-transmission probable. Because these two transfusion recipients
were hospitalized for at least 2 weeks each before onset of WNND, neither
patient was likely to have acquired infection from a mosquito bite.
Furthermore, for the patient who underwent transplant surgery on August 25,
transmission through the transplanted kidney is unlikely, given that neither
the organ donor nor the other organ recipient had evidence of WNV infection
Public Health Agency of Canada WNV Report
Public Health Agency of Canada WNV Report
AABB WNV
Biovigilence
Map
Includes ARC,
ABC, CBS and HQ
Update Nov 13
Usually significant delay
in updates
CBS provides data only
if Presumptive Positive
CBS WNV Screen Positive Donations - 2007
Clinic Info
No.
Cases
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
Date
2007-06-19
2007-07-03
2007-07-23
2007-07-26
2007-07-26
2007-07-27
2007-07-28
2007-07-30
2007-07-31
2007-07-31
2007-07-31
2007-08-01
2007-08-01
2007-08-02
2007-08-01
2007-08-03
2007-08-04
2007-08-07
2007-08-07
2007-08-07
2007-08-07
2007-08-07
2007-08-07
2007-08-07
2007-08-08
2007-08-08
2007-08-08
2007-08-08
2007-08-09
2007-08-09
2007-08-09
2007-08-09
2007-08-10
2007-08-10
2007-08-09
Province
Manitoba
Manitoba
Manitoba
Saskatchewan
Manitoba
Saskatchewan
BC
Saskatchewan
Saskatchewan
Manitoba
Saskatchewan
Saskatchewan
Saskatchewan
Saskatchewan
Manitoba
Manitoba
Saskatchewan
Saskatchewan
Saskatchewan
Saskatchewan
Manitoba
Manitoba
Manitoba
BC
Alberta
Saskatchewan
Manitoba
Saskatchewan
Saskatchewan
Saskatchewan
Saskatchewan
BC
Alberta
Saskatchewan
Manitoba
PHD
Winnipeg
North Eastman
Winnipeg
Saskatoon
Brandon
Regina Qu'Appelle
Vancouver(SK travel)
Saskatoon
Saskatoon
Winnipeg
Regina Qu'Appelle
Saskatoon
Saskatoon
Regina Qu'Appelle
Central
Winnipeg
Regina Qu'Appelle
Regina Qu'Appelle
Kelsey Trail
Regina Qu'Appelle
Assiniboine
Assiniboine
Assiniboine
S Vancouver Island
Calgary
Prince Albert Parkland
Central
Prince Albert Parkland
Regina Qu'Appelle
Regina Qu'Appelle
Regina Qu'Appelle
Fraser South (Winn travel)
David Thompson
Saskatoon
Winnipeg
Donor Info
PHD
South Eastman
North Eastman
Winnipeg
Saskatoon
Brandon
Regina Qu'Appelle
Fraser South
Saskatoon
Saskatoon
Winnipeg
Regina Qu'Appelle
Saskatoon
Saskatoon
Regina Qu'Appelle
Central
Winnipeg
Regina Qu'Appelle
Regina Qu'Appelle
Kelsey Trail
Regina Qu'Appelle
Assiniboine
Assiniboine
Assiniboine
S Vancouver Island
Calgary
Prince Albert Parkland
Central
Prince Albert Parkland
Regina Qu'Appelle
Regina Qu'Appelle
Regina Qu'Appelle
Fraser South
David Thompson
Saskatoon
South Eastman
Testing Information
Date Screened
2007-06-19
2007-07-05
2007-07-25
2007-07-27
2007-07-27
2007-07-28
2007-07-29
2007-07-31
2007-08-01
2007-08-01
2007-08-01
2007-08-02
2007-08-02
2007-08-03
2007-08-03
2007-08-04
2007-08-05
2007-08-08
2007-08-08
2007-08-08
2007-08-09
2007-08-09
2007-08-09
2007-08-09
2007-08-09
2007-08-10
2007-08-10
2007-08-10
2007-08-10
2007-08-10
2007-08-10
2007-08-11
2007-08-11
2007-08-11
2007-08-11
Screen Type
MP
MP
SU
MP
MP
MP
MP
SU
SU
MP
SU
SU
SU
SU
SU
SU
SU
SU
MP
SU
MP
MP
MP
MP
MP
SU
SU
SU
SU
SU
SU
MP
MP
SU
SU
2nd NAT
Pos
Pos
Pos
Pos
Pos
Pos
Pos
Pos
Pos
Pos
Pos
Pos
Pos
Pos
Pos
Pos
Pos
Pos
Pos
Pos
Pos
Neg
Pos
Neg
Neg
Pos
Pos
Pos
Pos
Pos
Pos
Pos
Pos
Pos
Pos
IgM
Neg
NT
Pos
Neg
Neg
Neg
Neg
Neg
Neg
Neg
Neg
Neg
Pos
Neg
Neg
Neg
Pos
Neg
Equiv
Neg
Neg
Neg
Neg
Neg
Neg
Pos
Pos
Neg
NT
NT
NT
NT
Neg
Neg
NT
IgG
Neg
NT
Pos
Neg
Neg
Neg
Neg
Neg
Neg
Neg
Neg
Neg
Neg
Neg
Neg
Neg
Neg
Neg
Neg
Neg
Neg
Neg
Neg
Neg
Neg
Neg
Neg
Neg
NT
NT
NT
NT
Neg
Neg
NT
Clinic Info
No.
Cases
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
Date
2007-08-09
2007-08-13
2007-08-14
2007-08-14
2007-08-14
2007-08-14
2007-08-14
2007-08-14
2007-08-15
2007-08-15
2007-08-16
2007-08-15
2007-08-15
2007-08-14
2007-08-16
2007-08-16
2007-08-16
2007-08-16
2007-08-16
2007-08-16
2007-08-16
2007-08-22
2007-08-22
2007-08-24
2007-08-25
2007-08-27
2007-08-28
2007-08-28
2007-08-29
2007-08-30
2007-09-08
2007-09-11
2007-09-12
2007-09-14
2007-09-17
Province
Saskatchewan
Saskatchewan
Saskatchewan
Saskatchewan
Saskatchewan
Manitoba
Manitoba
Saskatchewan
Alberta
Manitoba
Ontario
Saskatchewan
Saskatchewan
Saskatchewan
Saskatchewan
Alberta
Manitoba
Manitoba
Manitoba
Saskatchewan
Saskatchewan
Manitoba
Manitoba
Ontario
Saskatchewan
Manitoba
Saskatchewan
Saskatchewan
Saskatchewan
Saskatchewan
Saskatchewan
Saskatchewan
Saskatchewan
Saskatchewan
Saskatchewan
Donor Info
PHD
Saskatoon
Cypress
Saskatoon
Saskatoon
Saskatoon
Central
Winnipeg
Cypress
Palliser
Brandon
Thunder Bay
Heartland
Heartland
Saskatoon
Saskatoon
Chinook
South Eastman
South Eastman
Brandon
Saskatoon
Saskatoon
Brandon
Brandon
Toronto
Regina Qu'Appelle
Assiniboine
Regina Qu'Appelle
Sun Country
Regina Qu'Appelle
Regina Qu'Appelle
Saskatoon
Regina Qu'Appelle
Regina Qu'Appelle
Saskatoon
Saskatoon
PHD
Saskatoon
Cypress
Saskatoon
Saskatoon
Saskatoon
Central
Winnipeg
Cypress
Palliser
Brandon
Thunder Bay
Heartland
Heartland
Saskatoon
Saskatoon
Chinook
South Eastman
South Eastman
Assiniboine
Saskatoon
Saskatoon
Assiniboine
Assiniboine
Toronto
Regina Qu'Appelle
Assiniboine
Regina Qu'Appelle
Sun Country
Regina Qu'Appelle
Regina Qu'Appelle
Saskatoon
Regina Qu'Appelle
Regina Qu'Appelle
Saskatoon
Saskatoon
Testing Information
Date Screened
2007-08-11
2007-08-14
2007-08-15
2007-08-15
2007-08-15
2007-08-15
2007-08-16
2007-08-16
2007-08-16
2007-08-16
2007-08-17
2007-08-16
2007-08-16
2007-08-16
2007-08-17
2007-08-17
2007-08-17
2007-08-17
2007-08-17
2007-08-17
2007-08-17
2007-08-24
2007-08-24
2007-08-25
2007-08-26
2007-08-29
2007-08-29
2007-08-29
2007-08-30
2007-08-31
2007-09-09
2007-09-13
2007-09-13
2007-09-15
2007-09-18
Screen Type
SU
MP
SU
SU
SU
SU
SU
SU
MP
MP
MP
SU
SU
SU
SU
MP
SU
SU
SU
SU
SU
SU
SU
MP
MP
SU
SU
SU
SU
SU
SU
SU
SU
SU
SU
2nd NAT
Pos
Pos
Pos
Pos
Pos
Pos
Pos
Pos
Pos
Pos
Pos
Neg
Pos
Pos
Pos
Pos
Pos
Pos
Pos
Pos
Pos
Pos
Pos
Pos
Pos
Pos
Pos
Neg
Pos
Neg
Pos
Pos
Neg
Pos
Pos
IgM
NT
Pos
Neg
Pos
Neg
Pos
Pos
Neg
Neg
Neg
Neg
Pos
Equiv
Pos
Neg
Pos
Pos
Neg
Neg
Pos
Neg
NT
NT
Neg
Pos
Pos
Neg
Pos
Pos
Pos
Pos
Neg
Neg
Pos
Pos
IgG
NT
Neg
Neg
Pos
Neg
Neg
Neg
Neg
Pos
Neg
Neg
Pos
Neg
Pos
Neg
Neg
Pos
Neg
Neg
Pos
Neg
NT
NT
Neg
Neg
Pos
Neg
Pos
Pos
Pos
Pos
Neg
Neg
Pos
Pos
Number WNV Screen Positive Donations
No. of WNV Screen Positive Donations by Week
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Week Week Week Week Week Week Week Week Week Week Week Week Week Week Week Week Week
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
2003 (N=14)
0
0
0
0
1
0
2
4
2
3
0
2
0
0
0
0
0
2004 (N=0)
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
2005 (N=15)
0
0
0
0
0
1
2
1
8
1
0
0
0
1
1
0
0
2006 (N=8)
0
0
0
0
0
0
1
3
3
1
0
0
0
0
0
0
0
2007 (N=70)
1
0
1
0
0
5
10
19
20
4
5
1
3
1
0
0
0
Date
Cumulative WNV Screen Positive Donations by Week
Number WNV Screen Positive Donations
80
70
60
50
40
30
20
10
0
Week Week Week Week Week Week Week Week Week Week Week Week Week Week Week Week Week
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
2003 Cumulative
0
0
0
0
1
1
3
7
9
12
12
14
14
14
14
14
14
2004 Cumulative
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
2005 Cumulative
0
0
0
0
0
1
3
4
12
13
13
13
13
14
15
15
15
2006 Cumulative
0
0
0
0
0
0
1
4
7
8
8
8
8
8
8
8
8
2007 Cumulative
1
1
2
2
2
7
17
36
56
60
65
66
69
70
70
70
70
Date
Donations Screen for WNV by SUT and MP
per Week
Donations screened for WNV by Single Unit (SU) and Minipool (MP) per week
25000
20000
# Donations
15000
10000
5000
0
Actual SU # Samples (Risk)
MP
Week Week Week Week Week Week Week Week Week Week Week Week Week Week Week Week
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
566
519
208
338
0
777
1860 2237 3540 2146 2525
695
910
548
406
25
18278 17637 16330 18941 18232 16256 15117 13421 15741 17852 17797 17120 20272 18789 18451 18678
Week #
Positive WNV Donations by Screen Type, Year & Month
80
70
# Positive Donations
60
50
40
30
20
10
0
June July August
September
Total June July August
September
Total June July August
September
Total June July August
September
Total June July August
September
Total
2003
2004
2005
2006
2007
MP
0
1
11
0
12
0
0
0
0
0
0
1
6
2
9
0
0
4
0
4
1
6
15
0
22
SU
0
0
0
2
2
0
0
0
0
0
0
0
6
0
6
0
0
4
0
4
0
4
39
5
48
Year / Month
WNV NAT Screen Reactive Donors by Province
Province
Total Positive Donors
BC/Yukon
3*1
Alberta
41
Saskatchewan
401
Manitoba
211
Ontario
2
TOTAL
70
*2 donors with travel history
1 1 false positive donor (alt. NAT and antibody negative)
Alternate NAT and Antibody Results
Positive Equivocal
Negative
Not
tested
Alternate
NAT
63
-
7
0
IgM
22
2
37
9
IgG
14
0
44
9
Donor Characteristics
• Age Range 19 – 69
• First time vs Repeat donor
3 vs 67
• Sex
50
20
Male
Female
• Symptomatic*
– 40/70 donors reported symptoms
• 28 pre-donation
• 5 post donation
• 7 timing of symptoms unknown
– 3 Presence of symptoms unknown
– 27 Asymptomatic
*Donors reported symptoms ranging from mild headache to rash and muscle pains , chills and fever
Donor Studies
6 donors identified as WNV positive by SUT
Results of Replicate Testing 2005
Toronto + Calgary SU WNV Only
Follow Up Study
WNV Initial Screening
2nd
IgM IgG No.
NAT
SU Testing
Resolution Testing
MP Testing
ID No.
Screen
Type
2005-08-02 Ottawa
WNV 02
SU
+
-
-
6
5
1
5
5
0
1
1
0
2005-08-17 Ottawa
WNV 05
SU
-
-
-
6
0
6
0
0
0
6
0
6
2005-08-18 Windsor-Essex
WNV 09
SU
+
-
-
6
6
0
6
6
0
0
0
0
2005-08-18 South Eastman
WNV 10
SU
+
-
-
6
6
0
6
6
0
0
0
0
2005-08-19 Windsor-Essex
WNV 11
SU
+
-
-
6
6
0
6
6
0
0
0
0
2005-08-22 Central MB
WNV 13
SU
+
+
+
6
3
3
3
2
1
4
2
2
Date
Collected
Clinic PHD
Pos Neg No.
Pos Neg No.
Pos Neg
Proposed Studies on 2007 Donors
"What I need is an exact list of specific unknown problems
we might encounter." (Lykes Lines Shipping)
Proposed Follow-up Studies
• Donor Survey
– Survey of 70 WNV NAT positive donors
• Impact of positive WNV test on behaviour - self,
family
• Knowledge of West Nile – presence in community,
preventative measures
• Symptoms
Laboratory Studies and Strategy
Evaluation
• All SUT positives to be tested by MP in
replicates of (TBD).
• Effectiveness of SUT strategy evaluated.
• Viral load testing – Roche Diagnostics and
National Microbiology Lab (NML)
Winnipeg
• Viral sequencing and comparison to Idaho
strain (stable mutation at 3’NCR) - NML