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From: TSS ()
Subject: High incidence of subclinical infection of lymphoid tissues in scrapie-affected sheep flocks
Date: March 27, 2008 at 11:49 am PST

High incidence of subclinical infection of lymphoid tissues in
scrapie-affected sheep flocks

Journal Archives of Virology
Publisher Springer Wien
ISSN 0304-8608 (Print) 1432-8798 (Online)
Issue Volume 153, Number 4 / April, 2008
Category Original Article
DOI 10.1007/s00705-008-0035-8
Pages 637-644
Subject Collection Biomedical and Life Sciences
SpringerLink Date Tuesday, January 29, 2008

Gudmundur Georgsson1 , Jona Adalheidur Adolfsdottir1, Astridur Palsdottir1,
Einar Jorundsson1, 3, Sigurdur Sigurdarson2, 4 and Stefania Thorgeirsdottir1

(1) Institute for Experimental Pathology, University of Iceland, Keldur
v/Vesturlandsveg, 112 Reykjavík, Iceland
(2) Laboratory of Chief Veterinary Officer, Keldur, Reykjavík, Iceland
(3) Present address: Ministry of Education, Science and Culture,
Solvholsgata 4, 101 Reykjavík, Iceland
(4) Present address: Agricultural Authority of Iceland, Austurvegur 64, 800
Selfoss, Iceland

Received: 12 November 2007 Accepted: 27 December 2007 Published online: 29
January 2008

Abstract Prion diseases are characterized by a long incubation period. In
scrapie, sheep may incubate and spread the infection for several years
before clinical signs evolve. We have previously studied the occurrence of
subclincal infection in the brain. Now, we have studied the occurrence of
subclinical infection in the brain and several lymphoid tissues in two
scrapie-affected Icelandic sheep flocks by immunohistochemistry for PrPSc, a
molecular marker for infectivity, and correlated this with results of PrP
genotyping. At culling, one flock had one confirmed scrapie case, while the
other flock had two. Analysis of 106 asymptomatic sheep by immunostaining
for PrPSc revealed that the incidence of subclinical infection was 58.3% in
one flock and 42.5% in the other. PrPSc was only detected in lymphoid
tissues. The youngest positive sheep were 4 months old. PrP genotyping
showed that over 90% of the sheep were of a genotype which is moderately
sensitive to infection and may delay neuroinvasion. Our results show that
asymptomatic sheep may spread the infection during the long incubation
period of several years, which constitutes an important obstacle in the
eradication of scrapie. Our findings indicate that contamination of the
environment plays an important part in sustaining the infection.

----------------------------------------------------------------------------
----


Gudmundur Georgsson
Email: ggeorgs@hi.is


http://www.springerlink.com/content/u761171744280806/

http://scrapie-usa.blogspot.com/2008/03/high-incidence-of-subclinical-infection.html


SCRAPIE USA UPDATE MONTHLY REPORT JANUARY 2008


prepared February 20, 2008

Infected and Source Flocks

There were 27 scrapie infected and source flocks with open statuses (Figure
3) as of January 31, 2008. Two new source flocks and one new infected flock
were reported in January (Figure 4) with a total of 22 reported for FY 2008
(Figure 5). ....


snip...


Positive Scrapie Cases

As of January 31, 2008, 58 new scrapie cases have been confirmed and
reported by the National Veterinary Services Laboratories (NVSL) in FY 2008
(Figure 7). Of these, 52 were field cases and 6* were Regulatory Scrapie
Slaughter Surveillance (RSSS) cases (collected in FY 2008 and reported by
February 20, 2008). There were 8 positive cases for January which are
depicted in Figure 8. Seventeen cases of scrapie in goats have been
confirmed by NVSL since implementation of the regulatory changes in FY 2002
(Figure 9). The most recent positive goat cases were from the SAME HERD and
WERE BOTH CONFIRMED IN JANAURY 2008.


snip...


Caprine Scrapie Prevalence Study (CSPS)

CSPS was initiated in May 2007 to estimate the national prevalance of
scrapie in adult goats at slaughter. If no scrapie is found we will be able
to conclude that the prevalence in goats is greater than zero and less than
0.1 percent. AS of January 31, 2008, 2,942 goats have been sampled for
scrapie testing (1,515 in FY 2007 and 1,427 in FY 2008). Collection numbers
by quarter in FY 2008 is shown in Chart 8. To date, no goats have tested
positive for scrapie as part of this surveillance program. HOWEVER, THREE
POSITIVE GOATS have been identified this fiscal year through field
investigations. One was a clinical suspect submitted for testing and THE
OTHER TWO WERE MEMBERS OF THE OF THE BIRTH HERD OF THE CLINICAL CASE.


snip...


please see full text ;


http://www.aphis.usda.gov/animal_health/animal_diseases/scrapie/downloads/monthly_scrapie_rpt.pps

ATYPICAL NOR-98 SCRAPIE LOCATION UPDATE ON 5 DOCUMENTED CASES THIS YEAR ;


The flocks of origin are WY, CO, CA, IN, and MN.


personal communication USDA et al. ...TSS

snip...

INFECTED AND SOURCE FLOCKS AS of August 31, 2007, there were 33 scrapie
infected and source flocks with open statuses (Figure 3). Five new source
flocks and one new infected flock were reported n August (Figure 4) with a
total of 64 reported for FY 2007(Figure 5).


snip...


IN FY 2007 TWO FIELD CASES, ONE VALIDATION CASE, AND TWO RSSS CASES WERE
CONSISTENT WITH NOR-98 SCRAPIE. ...


(BRINGS A TOTAL OF 5 NOR-98 CASES DOCUMENTED IN 2007 IN USA. ...TSS)


http://www.aphis.usda.gov/animal_health/animal_diseases/scrapie/downloads/monthly_scrapie_rpt.pps


SCRAPIE TYPICAL AND ATYPICAL USA


http://nor-98.blogspot.com/


http://scrapie-usa.blogspot.com/


TSS




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