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

Wednesday, March 26, 2008 High incidence of subclinical infection of lymphoid tissues in scrapie-affected sheep flocks

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.

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Gudmundur Georgsson Email: ggeorgs@hi.is

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


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). ....

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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.

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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.

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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

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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).

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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