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Experience With Testing Blood Donors for Babesia. David A. Leiby, PhD. Transmissible Diseases Department American Red Cross Holland Laboratory and Department of Microbiology and Tropical Medicine George Washington University. Outline. B. microti seroprevalence studies

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slide1

Experience With Testing Blood Donors for Babesia

David A. Leiby, PhD

Transmissible Diseases Department

American Red Cross Holland Laboratory

and

Department of Microbiology and Tropical Medicine

George Washington University

slide2

Outline

B. microti seroprevalence studies

2009 NAT pilot study

Longitudinal natural history study

Lookback results

slide3

B. microti Seroprevalence Study

  • conducted from 1999 to present
  • primarily focused in Connecticut
    • recently expanded to include MA, NH & ME
  • donors tested by IFA for antibodies to B. microti
    • cutoff titer of 1:64
  • IFA positive donors deferred indefinitely
    • during first 2 years, deferred based on PCR +
  • studies initially targeted highly endemic areas, but subsequently expanded statewide
slide4

Year # Tested Antibody + (%) PCR + (%)

19993,490 30 (0.9) 10/19 (53)

2000 2,681 28 (1.0) 10/18 (56)

  • 2,162 30 (1.4) 2/25 (8)
  • 2,230 18 (0.8) 2/14 (14)
  • 1,989 34 (1.7) 2/20 (10)
  • 2,864 43 (1.5) 1/33 (3)
  • 1,841 25 (1.4) 0/10 (0)
  • 3,251 39 (0.9) 3/19 (16)
  • 5,267 42 (0.8) 1/22 (5)

CT Donor Seroprevalence: 1999-2007

slide6

Seroprevalence/10,000 donations

Spatial cluster 1

Spatial cluster 2

Johnson et al., Transfusion 2009;49:2574-2582

slide7

Piloting NAT for B. microti

  • pilot study of ~1,000 CT donations
  • collected August/October 2009 from Middlesex and New London Counties
  • 1,002 tested to date:
    • 25 (2.5%) IFA positive
    • 3 (0.3%) PCR positive (2 IFA +, 1 IFA -)
      • all identified by first week of September
  • 1 apparent window period infection detected
    • number likely low
    • acutely infected donors too sick to donate?
  • role for NAT during tick season?
slide8

Babesia NAT Approach

  • seasonally triggered
  • May through September
  • targets acute or “window period” infections
  • technologic hurdles remain:
    • PCR sensitivity sufficient, but . . .
    • parasitemia low compared to viral infections
    • requires whole blood
    • limited volume for testing
    • considerations of concentration techniques
slide9

Babesia Natural History Study

  • long-term, ongoing study in CT and MA
  • enrolling B. microti seropositive donors from seroprevalence study
  • tested every 30 - 60 days
    • serology
    • blood smear
    • PCR
    • hamster inoculation (w/ CDC)
  • risk-factor questionnaires
    • initial risk
    • potential re-exposure
  • investigate infection/resolution patterns over time
slide10

Natural History Study Observations

  • 227 seropositive donors enrolled to date
  • 184 evaluable donors from 2000–2008
    • 86 (47%) sero-reverted to baseline negative
    • 98 (53%) remained seropositive
      • 37 (38%) resolving infection
      • 30 (31%) chronic infections
      • 12 (12%) re-infections
      • 19 (19%) insufficient data
slide11

Resolution of Babesia Infection: Part I

DateIFAPCRHamster

07/21/00 1:512 ND ND

08/15/00 1:256 Pos. Pos.

09/18/00 1:128 Pos. Neg.

12/01/00 1:128 Neg. Neg.

04/06/01 <1:64 Neg. Neg.

07/13/01 <1:64 Neg. Neg.

10/12/01 <1:64 Neg. Neg.

Released from study

slide13

Resolution of Babesia Infection: Part II

DateIFAPCRHamster

07/28/03 1:128 ND ND

08/25/03 1:128 Neg. Neg.

10/17/03 1:64 Neg. Neg.

03/16/04 1:64 Neg. Neg.

07/01/04 <1:64 Neg. Neg.

10/01/04 <1:64 Neg. Neg.

Released from study

slide14

Persistent High Ab Titer = Chronic Carrier

DateIFAPCRHamster

08/24/00 1:512 ND ND

10/02/00 1:512Pos. Pos.

11/28/00 1:512 Neg.Pos.

11/30/00 initiated 10 day treatment for babesiosis

03/30/01 1:512 Neg. Neg.

05/31/01 1:512 Neg. Neg.

09/10/01 1:256 Neg. Neg.

12/01/01 1:512 Neg. Neg.

02/25/02 1:512 Neg. Neg.

07/18/03 1:512 Neg. Neg.

Released from study

slide16

Re-exposure to B. microti?

DateIFAPCRHamster

07/07/00 1:64 ND ND

08/03/00 1:128 Pos. Pos.

09/21/00 1:128 Pos. Neg.

11/08/00 1:256 Neg. Neg.

02/15/01 1:128 Neg. Neg.

04/28/01 1:64 Neg. Neg.

08/17/01 1:128 Neg. Neg.

10/26/01 1:64 Neg. Neg.

12/21/01 <1:64 Neg. Neg.

02/22/02 <1:64 Neg. Neg.

05/02/02 1:256 Neg. Neg.

07/12/02 1:64 Neg. Neg.

10/08/02 1:128 Neg. Neg.

12/13/02 1:64 Neg. Neg.

02/21/03 1:64 Neg. Neg.

05/12/03 1:128 Neg. Neg.

07/23/03 1:128 Neg. Neg.

slide18

Asymptomatic Chronic Carrier

DateIFAPCRRT-PCRHamster

07/31/03 1:1024 ND ND ND

08/26/03** 1:1024 Pos. Pos. Pos.

08/29/03 initiated 10 day treatment for babesiosis

09/22/03 1:1024 Neg. Neg. Neg.

10/23/03 1:256 Neg. Pos. Neg.

01/02/04 1:1024 Neg. Pos. Neg.

03/16/04 1:1024 Pos. Pos. Neg.

04/27/04 1:1024 Neg. Pos. Neg.

06/26/04 1:1024 Neg. Pos. Neg.

09/23/04 1:1024 Neg. Pos. Neg.

11/29/04 1:128 Neg. Neg. Neg.

01/21/05 1:1024 Neg. Neg. Neg.

03/28/05 1:512 Neg. Neg. Neg.

05/17/05 1:512 Neg. Pos. Neg.

07/12/05 1:256 Neg. Pos. Neg.

09/19/05 1:256 Neg. Neg. Neg.

12/02/05 1:512 Neg. Neg. Neg.

03/07/06 1:512 Neg. Pos. Neg.

06/28/06 1:512 Neg. Neg. Neg.

* 79 year-old male

** positive on blood smear

slide19

Chronic Carrier – NIH Blood Donor

  • donor in the NIH blood program
  • implicated in a transfusion case
    • asymptomatic chronic carrier
    • hereditary hemochromatosis patient
    • frequent marathon runner
    • excellent health
  • implicated donation
    • Ab titer of 1:1024
    • PCR negative
  • follow-up studies
    • implicated in additional transfusion case
    • Ab titers remain at 1:1024 (n=11)
    • never PCR positive
slide21

Summary

  • seroprevalence among CT donors ~ 1% each year
    • portion of donors parasitemic
    • focal endemicity, but statewide distribution
  • NAT role indicated for seasonal, acute infections
  • natural history of babesial infection
    • majority of donors resolve infection
      • considerations for re-entry
    • chronic carriers pose significant transmission risk
  • lookback investigations verify transmission risk
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