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September 30, 2002
West Nile Virus:
WNV continues (not surprisingly), but recent reports have suggested the virus may infect and replicate in more species than previously thought. Although there have been several serologic reports in other species (which, for the most part, I haven't forwarded), virus isolations have not been commonly found. Now species from which virus has been isolated, tissue immunohistochemistry positive, or PCR amplified genome include: sheep, mountain goats, squirrels, and some camelids. The mountain goat, squirrels, and alpaca have had clinical disease. In addition, WNV has apparently been isolated from louse flies collected from a symptomatic great horned owl (see report below), though what role these ectoparasites might play in WNV transmission is unknown. In humans, WNV genetic material (not necessarily live virus) has been detected in breast milk, and WNV transmission through organ transplantation and blood transfusion have been documented. The human case count reported by CDC as of today is 2405 cases and 117 deaths. Case reports have been highest in the midwest (Illinois - 551, Michigan - 314, and Ohio - 266). Louisiana ranks high also at 287. As of last week, USDA report 6223 equine cases of WNV.
vCJD:
In a study of tonsillectomized and appendectomized tissues from over 8300 patients in the UK (from 1995-1999; see report below), 1 sample came back positive for vCJD prion protein-res. As an estimated prevalence this translates into 120 cases per million people, or about 6000 cases of vCJD in the British population. Of course, with only one case the 95% confidence interval is wide (0.5 to 900 cases per million people). Italy's first case of vCJD disease in a 25y.o. woman was reported on Friday.
CWD:
On the CWD front a few new happenings:
Thomas J. Roffe, PhD, DVM
Northern Rocky Mountain Science Center
USGS-BRD
FWP Bldg, 1400 S. 19th Ave.
Bozeman, MT
T: 406-994-5789
F: 406-994-4090
Cell: 406-539-4955
Supporting Documents:
Date: Tue 24 Sep 2002
From: John P. Maher <jmaher@chesco.org>
Louse Flies (_Hippoboscidae_) Test Positive for West Nile Virus
A pool of Hippoboscid flies has tested positive for West Nile virus in Dauphin Co (Pennsylvania). These flies are also called louse flies and are ectoparasites on birds and mammals. We have no idea regarding the importance of these insects because no work has been done with respect to Hippoboscid vector competence for West Nile virus. If they are capable of vectoring West Nile virus, they could be very important enzootic vectors in the wild in roosting areas and among nest mates. Birds in captivity, such as those in zoos and bird rehab centers, could also be disproportionately affected. The flies were collected from a symptomatic Great horned owl.
Date: Thu 26 Sep 2002
From: ProMED-mail <promed@promedmail.org>
Source: Eurosurveillance Weekly, Issue 39, Thu 26 Sep 2002 [edited]
<http://www.eurosurv.org/update/
Plans for a Tonsil Archive
A paper published in the British Medical Journal has provided new information on the prevalence of preclinical variant Creutzfeldt-Jakob disease [abbreviated as vCJD of CJD (new var.) in ProMED-mail] in the United Kingdom (UK) (1,2). A distinctive feature of vCJD is the widespread distribution of an abnormal prion protein in peripheral lymphoid tissue (3,4), which may be detectable before any symptoms develop (5). The authors looked retrospectively for the presence of abnormal prion protein in 8318 appendectomy and tonsillectomy samples and found one positive appendix. It is not known whether an asymptomatic person with detectable abnormal prion protein will go on to develop vCJD but, as discussed in the paper, 19 of 20 appendixes removed at autopsy from patients with vCJD have shown accumulation of abnormal prion protein, as did the appendixes removed from 2 patients prior to disease onset (5).
Whilst the paper does report the first estimate of the prevalence of abnormal prion protein based on population testing, larger studies are needed to provide a more precise estimate. In conjunction with the publication of the paper, the Chief Medical Officer for England, Sir Liam Donaldson, announced plans to establish a prospective archive of tonsils, which will be used to provide improved estimates of the prevalence of preclinical vCJD (6). Large prospective studies of tonsil tissue are thought to offer the best opportunity for estimating the prevalence of preclinical vCJD. Outside of the central nervous system, tonsil tissue is the best tissue for the detection of the abnormal prion protein in vCJD (3), and unfixed tissue specimens allow efficient testing.
The Public Health Laboratory Service in London has been asked to coordinate the development of the tonsil archive and will be working with England's Department of Health, ear, nose, and throat surgeons and pathologists to achieve this goal.
The archive will be established on an unlinked anonymous basis, which means that each specimen will have personal identifying information irreversibly removed before testing and there will be no way of linking individual tonsil or test results back to the patient from whom they came. This is the same principle that has been used since 1990 to provide crucial, and otherwise unavailable information on the prevalence of HIV and other blood-borne virus infection in the UK (7,8).
References:
(1) PHLS. The prevalence of abnormal prion
protein: new data and plans for a tonsil archive. Commun Dis Rep CDR Wkly
2002; 12(39).
<http://www.phls.co.uk/publications/cdr/index.html>
(2) Hilton DA, Ghani AC, Conyers L, Edwards P,
McCardle L, Penney M, Ritchie D, Ironside JW. Accumulation of prion protein in
tonsil and appendix: review of tissue samples. BMJ 2002; 325: 633-4.
<http://bmj.com/cgi/reprint/325/7365/633.pdf>
(3) Hill AF, Butterworth RJ, Joiner S, Jackson G, Rossor MN, Thomas DJ, Frosh A, Tolley N, Bell JE, Spencer M, King A, Al-Sarraj S, Ironside JW, Lantos PL, Collinge J. Investigation of variant Creutzfeldt-Jakob disease and other human prion diseases with tonsil biopsy samples. Lancet 1999; 353: 183-9.
(4) Wadsworth JD, Joiner S, Hill AF, Campbell TA, Desbruslais M, Luthert PJ, Collinge J. Tissue distribution of protease resistant prion protein in variant Creutzfeldt-Jakob disease using a highly sensitive immunoblotting assay. Lancet 2001; 358: 171-80.
(5) Variant Creutzfeldt-Jakob disease. Lancet 1998; 352: 703-4.
(6) Chief Medical Officer welcomes vCJD research results. Department of Health press release: reference 2002/0390. Friday 20th September 2002.
(7) Nicoll A, Gill ON, Peckham CS, Ades AE, Parry J, Mortimer P, Goldberg Noone A, Bennett D, Catchpole M. The public health applications of unlinked anonymous seroprevalence monitoring for HIV in the United Kingdom. Int J Epidemiol 2000; 29: 1-10.
(8) Unlinked Anonymous Surveys Steering Group. Prevalence of HIV and hepatitis infections in the United Kingdom 2000: Annual report of the Unlinked Anonymous Prevalence Monitoring Programme. London: Department of Health; December 2001.
Date: 21 Sep 2002
From: ProMED-mail <promed@promedmail.org>
Subject: Chronic wasting disease, captive deer - USA (Wisconsin)
Source: Z wire/UPI
http://www.zwire.com/site/news.cfm?newsid=5445404&BRD=1594&PAG=740&dept_id=331520&rfi=6>
Chronic wasting disease may be spreading
MADISON, Ill., Sep 20, 2002 (United Press International via COMTEX) --
Wisconsin natural resources officials Friday worried chronic wasting disease has spread from the initial outbreak area near Madison to infect deer in other parts of the state. The Department of Natural Resources said a white-tailed buck shot on a game farm in Portage County tested positive for the disease, which is similar to mad cow in cattle. Discussions were under way on whether to speed up plans to test the deer population throughout the state.
The infected deer was killed Sept. 4 by a hunter on a preserve. Officials said the buck is believed the first captive deer to test positive for the disease in the nation. Previously only captive elk had tested positive for chronic wasting disease. Investigators have not yet determined the infected animal's movements or whether the hunter processed meat.
The game farm has been quarantined, along with another game farm in Walworth County. It has not yet been determined whether all the animals will be destroyed. There are 946 game farms in Wisconsin, where hunters pay up to $100 to hunt. The farms have more than 35,000 animals, many of which came from Nebraska, Colorado and Saskatchewan, where chronic wasting disease first surfaced. Investigators have been eyeing game farms as a possible source of the disease in the wild deer population.
The state authorized four off-season deer hunts to kill 25,000 animals in a bid to stop the disease from spreading from the initial outbreak area near Mount Horeb, where 31 infected deer have been found. In Minnesota, the Animal Health Board said Thursday officials will destroy the remaining 48 elk on a farm where the state's first case of chronic wasting disease was discovered last month. The animals will be shipped from a farm in Aitkin, Minn., to the University of Minnesota's Veterinary Diagnostic Laboratory in St. Paul, where they will be tested and destroyed. Brain-stem samples will be sent to the U.S. Agriculture Department lab in Ames, Iowa. Like mad cow in cattle and scrapie in sheep, chronic wasting disease is caused by abnormal proteins that attack the brain and nervous system, causing weight loss and behavioral changes. Researchers have not yet figured out how chronic wasting disease is spread or whether it is transmittable to humans.
U.S. Department of the Interior | U.S. Geological Survey
URL: http://biology.usgs.gov/cro/WNV9-30-02.htm
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