Holland Laboratory Tests Used In Blood Screening (II) Test Performance; Optimal Use of Reference Panels David A. Leiby, PhD Head, Transmissible Diseases.

Holland Laboratory

Tests Used In Blood Screening (II)Test Performance; Optimal Use ofReference Panels

David A. Leiby, PhDHead, Transmissible Diseases

WHO Consultation27-28 January 2009

WHO Headquarters, Geneva

Common Serologic Assays for T. cruzi

indirect immunofluoresence (IFA) indirect hemagglutination (IHA) ELISA RIPA Western/immuno blots rapid tests*

* not used for blood screening

U.S./Canadian Transfusion Cases:

1987: California - Mexican donor

1989: New York City - Bolivian donorManitoba - Paraguayan donor

1993: Houston - unknown donor

1999: Miami - Chilean donor

2000: Manitoba - German/Paraguayan donor

2002: Rhode Island – Bolivian donor

Impact of Latin American Immigration

LA Seroprevalence: 1996-98

% D

onor

s P

osit

ive

0.000

0.002

0.004

0.006

0.008

0.010

0.012

0.014

0.016

0.018

1996 1997 1998

1/9,900

1/7,200

1/5,400

Leiby et al., Transfusion 2002;42: 549-555

Models for Testing/Implementation

universal blood screening screening + confirmatory assays parallel testing (2-3 assays)

risk-factor models birth in endemic country lived in rural area, thatched roof, vector

exposure, etc. immunosuppressed patients

must identify recipients at greatest risk test each donor only once/twice

logistically complex needs cost/benefit analysis analysis of sensitivity

T. cruzi Ab Testing

Sample sent fromNTL for RIPA

Positive, Indeterminate, Negative

Index donation

Repeat Reactive Non-Reactive

No Actions

SSO collates test resultsand sends reports

Retrieve index frozen plasma or index retention sample (IRS)

Defer donor and enroll in Chagas follow-up study (CFS)

Current ARC Testing Algorithm

Chagas Follow-Up Studies

RIPA Positive Donor

Donor follow-up: questionnaire2 clot tubes2 EDTA tubes3 heparin tube

T. cruzi Ab TestingRIPAPCR

Hemoculture

SSO collates test results and sends reports

Donor Management Practices in U.S.

RRs notified/deferred supplemental testing encouraged

no FDA licensed tests exists RIPA most sensitive test available

donor counseling including donor follow-up studies encouraged

no donor reentry refer RIPA positive donors to physicians recipient tracing for RIPA positive donors

T. cruzi Reactive Donors (01/29/07-11/30/08)

Total Cases RIPA Pos RIPA Reported

2633 639 (25%) 2597

17.8 million donations screened0.015% RR rateRR from 46 states (-DE, RI)RIPA pos (25%) from 38 states (+PR, DC)60% from FL and CA (1:3700-1:7500)Overall: 1:27,000

24

2673

343

25115

95

219

19

64

58

70

41

25

17

30

464

29

PR

21

30

12

59

37

45

77

6

52

80

16 9

50

5541

39

25

33

13

31

39

35

23

21

12

8

4

9

15DC

2

Continental U.S. Map: RIPA Positives (thru 11/30/08)

Total Repeat Reactive RIPA Positive RIPA Negative/Ind RIPA Pending/NT

2989 735 2135 / 45 74

>80% from ARC/BSL

22 Month Experience – ARC

Donation Type No. Screened No. RIPA Positive Prevalence

Total Donors 5,459,496 235 1:23,232

Allogeneic 5,046,741 225 1:22,430

Autologous 65,960 6 1:10,993

Pheresis 346,795 4 1:86,699

Total Donations 12,059,270 235 1:51,316

Allogeneic 10,666,437 225 1:47,406

Autologous 99,863 6 1:16,644

Pheresis 1,292,970 4 1:323,243

2,482,904 donors contributed 2,317,801 person years(only intervals between donations that were tested were counted)

+ - %

PCR

(EDTA)22 106 17

Hemoculture

(Heparin)9 105 8

PCR/Hemoculture Results for RIPA Pos Donors

0

2

4

6

8

10

12

14

16

18

Do

no

r S

tatu

s

8/1

/2006

9/1

/2006

10/1

/2006

11/1

/2006

12/1

/2006

1/1

/2007

2/1

/2007

3/1

/2007

4/1

/2007

5/1

/2007

6/1

/2007

7/1

/2007

8/1

/2007

9/1

/2007

10/1

/2007

11/1

/2007

12/1

/2007

1/1

/2008

2/1

/2008

3/1

/2008

4/1

/2008

5/1

/2008

6/1

/2008

7/1

/2008

8/1

/2008

9/1

/2008

10/1

/2008

11/1

/2008

First Time (n=250, 63.45%) Repeat (n=144, 36.55%)

RIPA Confirmed Positive Donors (n=394)

Donor Demographics to 11/30/08

RIPA Pos (N=394)~ FT donors 250 (63%)~ RPT donors 144 (37%)~ Male 212 (54%)~ Female 182 (46%)~ Country of birth (N=149)

◦ Mexico 44

◦ US 37

◦ El Salvador 24◦ Bolivia

15◦ Honduras 6◦ Colombia 5◦ Argentina, Guatemala 4◦ Brazil 3◦ Ecuador, Nicaragua 2◦ Paraguay, Chile, Somalia 1

RIPA Neg/Ind (N=1490)~ FT donors 414 (28%)~ RPT donors 1076 (72%)~ Male 898 (60%)~ Female 592 (40%)~ Country of birth (N=420)

◦ US 400◦ India

3 ◦ China, Germany 2◦ Thailand, Taiwan, Cuba, Hungary,

New Zealand, Barbados, Ecuador, Panama, Ukraine, Venezuela, Canada 1

◦ Colombia 2*

*21-37 years in Colombia, 1/2 with ECGirregularities and 1 with upper GI symptoms

Autochthonous Transmission Summary

45 potential autochthonous cases identified from screening US blood donors 37 from the ARC 7 appear to be likely cases

5 parasitemic 2 donors thoroughly investigated by CDC (MS)

another 7 have other risk factors some may be false positive

continued investigation needed to determine frequency and risk factor (e.g., hunting, camping, time spent outdoors, etc.)

US-derived T. cruzi (USTC) study participants CDC, ARC and UBS

additional questionnaire re risk; CDC and ARC IRB approved

0

5

10

15

20

25

30

n1 n6n11 n16 n21 v4 v9 v1

4v1

9v2

4v2

9v3

4v3

9v4

4v4

9v5

4v5

9v6

4v6

9v7

4v7

9v8

4v8

9v9

4

Testing Week (IND (n) Start 08/28/06, IVD (v) Start 01/29/07)

Ca

se

s

RIPA pos (N = 24 ) RIPA neg/pend (N = 625 )

RIPA Positive Donors

Prior Non-reactive/Untested Donations

16 with prior S/CO values: 0.12-0.98 5 with multiple prior negative donations8 QNS or NT donations Unlikely to be true “incident” infections!

IND/clinical trial (28/08/06 -28/01/07) PPV = 32 RIPA pos/63 RR = 51%; pos in 2 states RR rate = 63/148,969 = 0.042% Prevalence = 32/148,969 = 1:4655

Nationwide screening (29/01/07-30/11/08) PPV = 639 RIPA pos/2597 RR RIPA tested = 25%;

pos in 38 states (+ PR, DC) 60% from FL and CA (1:3700-1:7500)

RR rate = 2597 RRs/>17.8 x 106 donations = 0.015% Projected prevalence = 1:27,000

Test Performance

Sensitivity of Universal Testing (Ortho ELISA PI)

860/861 = 99.88% (95% CI = 99.35% to 100.00%)

Proposed Chagas Reference Standard

requirements must include T. cruzi I and II

broad geographic reactivity pooled vs. neat? sensitivity in diluted samples targeted antibody titers stability over time

specified characteristics 1 medium reactive from south 1 medium reactive from north 1 clear negative

Importance of Global Reference Standards

test validation quality control comparisons with other tests

Interested Parties

test manufacturers evaluate candidate antigens measure sensitivity

regulatory agencies determine analytic sensitivity reproducibility/proficiency compare assays

blood establishments assay evaluation quality assessment

research institutions diagnostic centers

facilitate comparison with other laboratories internal controls

Summary & Conclusions

significant number of U.S. blood donors infected with T. cruzi 639 confirmed positives nationwide distribution 1:27,000 donors infected

current test performance 99.88% sensitivity 25% PPV

need for a global reference standard test validation quality control assay comparison

reference standard characteristics broad geographic reactivity is critical

Acknowledgements

American Red Cross Susan Stramer, SSO Greg Foster, SSO David Krysztof SSO Rebecca Townsend SSO Megan Nguyen, HL Melanie Proctor, HL Ross Herron, West Div Pamela Kahm, West Div Norma Espinoza, West Div Kay Crull, West Div

Blood Systems Laboratories Sally Caglioti Frank Radar Larry Morgan