Paper on CWD in captive elk

[Guest guest]

Subj: Paper on CWD in captive elk

Date: 4/28/99 1:24:16 PM Eastern Daylight Time

From: jmiller@... (Janice M. )

Sender: BSE-L@... (Bovine Spongiform Encephalopathy)

Reply-to: BSE-L@... (Bovine Spongiform Encephalopathy)

To: BSE-L@...

In response to the comments of Dr. Tom Pringle on April 23, in the item

headed *explosive paper on CWD under-diagnosis still under wraps,* I would

like to make the following clarification. The work was done last summer (not

16 months ago, as reported in the item posted), a manuscript was subsequently

submitted through the ARS approval system, and final approval was received

September 28, 1998. The paper was then submitted as a brief communication to

Veterinary Record. The journal returned the manuscript in December with

reviewer comments that included many helpful suggestions for improvement.

However, the major concern was that the work should have presented a more

detailed description of the neuroanatomical PrPSc localizations.

Unfortunately, we were not able to meet such a requirement because the brain

samples that had been collected were not appropriate for such a study. In

view of this situation, we decided to withdraw the paper from consideration

by Veterinary Record and the senior author is now rewriting the paper for

submission to a different journal.

With regard to specific information presented in the paper, it should be

noted that the 17 animals examined were a selected group taken from a very

large herd and the selection process was not intended to provide a valid

assessment of overall CWD prevalence.

I don*t think people familiar with the TSE literature on PrP

immunohistochemistry (IHC) will be at all surprised that we were able to

detect positive brains in elk that had not yet developed clinical signs or

lesions. This kind of observation was reported several years ago using

laboratory animal models of scrapie. Furthermore, in our 1993 and 1994

papers on the use of IHC for scrapie diagnosis in sheep, we reported finding

many IHC positive brains that had been designated as only suggestive or

inconclusive for scrapie by histopathological criteria. Since that time the

APHIS National Veterinary Services Laboratory has been using IHC for

diagnosis of TSEs. According to Drs. Detwiler and Al , all brains

from sheep, goats, cattle, deer, and elk with neurological disease are

examined histologically and by IHC. Brains from the *downer cow*

surveillance program are also examined by both tests. APHIS, with the

assistance of state animal health and wildlife officials, has tested over

2000 brain samples from free-ranging cervids in Nebraska, South Dakota,

Kansas, Michigan, and New Jersey. All brains were negative for PrPSc by IHC.

State diagnostic laboratories know about the availability of IHC testing at

the NVSL and tissue samples from suspect cases are sent to that laboratory on

a referral basis. I hope that someone directly involved in the Colorado and

Wyoming CWD surveillance programs will comment on their use of IHC. However,

I can say that from conversations with Drs. Mike , Terry Spraker, and

Beth , I know that IHC has been used routinely in the diagnostic

laboratories of both states for several years so undoubtedly the 1998

prevalence report was based on that type of testing procedure.