Subject: FUTURE ASSESSMENT OF LIKELY vCJD INFECTIVITY ASSOCIATED WITH PLASMA
PRODUCTS
Date: May 3, 2007 at 8:47 am PST
FUTURE ASSESSMENT OF LIKELY vCJD INFECTIVITY ASSOCIATED WITH PLASMA PRODUCTS
Conclusions
11. The available data show that blood is infectious during the preclinical
stage
of vCJD. Although the precise time in the incubation period of vCJD at
which blood becomes infectious is unclear, data from animal models
suggests it may be infectious from at least, if not before, the middle of
the
incubation period. The source of infectivity in blood is not understood.
Data
from rodent studies suggests that infectivity in whole blood is around 10
ID/mL and that it mostly resides in the plasma and white blood cell
components with infectivity associated with white blood cells substantially
depleted by extensive washing. However, additional information from other
animal models is required to assess whether these findings may be closely
representative of vCJD infectivity in human blood. It is clear that an
infectious dose in blood can be disseminated but not diluted by distribution
to a large number of recipients. Consequently, pooling of potentially
infectious material, or in other ways disseminating infectious material
between a number of recipients, will not reduce the number of people
infected, and is likely to increase the number of people infected.
SEAC
July 2006
http://www.seac.gov.uk/papers/97-5.pdf
TSS
PRODUCTS
Date: May 3, 2007 at 8:47 am PST
FUTURE ASSESSMENT OF LIKELY vCJD INFECTIVITY ASSOCIATED WITH PLASMA PRODUCTS
Conclusions
11. The available data show that blood is infectious during the preclinical
stage
of vCJD. Although the precise time in the incubation period of vCJD at
which blood becomes infectious is unclear, data from animal models
suggests it may be infectious from at least, if not before, the middle of
the
incubation period. The source of infectivity in blood is not understood.
Data
from rodent studies suggests that infectivity in whole blood is around 10
ID/mL and that it mostly resides in the plasma and white blood cell
components with infectivity associated with white blood cells substantially
depleted by extensive washing. However, additional information from other
animal models is required to assess whether these findings may be closely
representative of vCJD infectivity in human blood. It is clear that an
infectious dose in blood can be disseminated but not diluted by distribution
to a large number of recipients. Consequently, pooling of potentially
infectious material, or in other ways disseminating infectious material
between a number of recipients, will not reduce the number of people
infected, and is likely to increase the number of people infected.
SEAC
July 2006
http://www.seac.gov.uk/papers/97-5.pdf
TSS