Transcript Infectivity of blood Adham

Infectivity of blood
By Dr. Adham Abdulmonem Saleh
M.B.B.Ch. – M.Sc in Anesthesia
Assistant lecturer of Anesthesia & ICU
Ain Shams University
With the introduction of transfusion-induced
AIDS, the infectivity by homologous blood
transfusion has received renewed attention.
In fact, for many years, blood banks use one or
two tests (i.e., syphilis and hepatitis B surface
antigen) to screen blood. In recent years, many
more tests have been added.
Overall, blood is probably safer than it has
been for years.
Infectious complications
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Viruses
HCV
HBV
HIV
HTLV
Cytomegalovirus
Epstein-Barr virus
Parvovirus B19
West Nile
v CJD
 Spirochetes
 Treponema pallidum
 Borrelia burgdorferi
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Parasites
Plasmodia
Trypanosoma cruzi
Toxoplasma gondii
Leishmania donovani
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Bacteria
Staphylococcus
Salmonella
Yersinia enterocolitica
 Risk of transmitting infection to recipients has been
dramatically reduced in the past decades, due to:
Improved donor selection.
Sensitive serologic screening assays.
Application of viral inactivation procedures during
manufacturing of plasma products.
1/1
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1/1,0
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1/10,0
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1/100,0
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1/1,000,0
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Adapted from Transfusion 2000; 40:143-159
I- viral:
Major sources of remaining risk are:
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Window period donation
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Viral variants not detect by current assays
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Immunosilent donor
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Laboratory testing error
 The greatest threat to the safety of blood supply
is the donation by seronegative donors during
the infectious window period
 Window period donation accounts for 90% or
more of the residual risk (Report of the
Interorganization Task Force on NAT Testing of
Blood Donors, 2000)
 Period precedes the development of antibodies
during the initial infection
 Eclipse phase of the window period is the very
initial phase after exposure when virus
replication is restricted to tissue sites and there
is no detectable viraemia
 Infectious phase of window period is after
eclipse and before seroconversion
Events in early viral infection
WP1
Exposure
WP2
Viremia
Eclipse
Serological
Detection
Infectivity
Estimates for WPs from Exposure to
Seroconversion Following Discrete
Parenteral Exposures
Virus
Source
N
Point Est
HIV
Needlestick
51
46 days
95% CI
(range)
10 - 190
HCV
Transfusion
46
71 days
33 - 128
HBV
Transfusion 7/15
59 days
(37 - 87)
51 days
(36 - 72)
HTLV Transfusion
24
Immunosilent carriers: chronic antibody
negative carriers
Persistent viremia in absence of detectable
seroconversion
 Case reports for HIV, HCV, and HBV
 Recipient infection via transfusion has
been documented for HCV
 Appears to be rare
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II. Bacterial
 Contamination unlikely in products stored for > 72 hours
at 1-6 0 C
 gram –ve, gram +ve bacteria
most frequent – Yersinia enterocolitica endotoxin
 Common in Platelets stored at room temperature for 5
days, with infection rate of 0.25%
III. Protozoal
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Trypanosoma cruzi (Chaga’s disease)
Malaria
Toxoplasmosis
Leishmaniasis
Serological Testing
for Infectious markers
 HIV – Ag
 Anti – HIV
 HBsAg
 Anti – HCV
 Test for syphilis
Future
 Screening other virus for specific blood products for
specific patient group, eg. screening Parvovirus B19 for
Anti-D Ig
 Screening for new transfusion-transmitted viruses