Back to the West Nile Virus listserv archive.

Date: July 31, 2003
Posted by: Joseph Therrien (jetherri@gw.dec.state.ny.us)

Subject: VecTest Updates

Below are the NYSDEC's Wildlife Pathology Units latest summary of 
results for WNV VecTests on oral swabs.

As anticipated from early reports and publications, the false 
negatives are an order of magnitude or more higher than false 
positives. However, we still have a small sample that will grow 
substantially because WNV seems to be rapidly increasing in 
prevalence in New York. The combination of false negatives and false 
positives remains of great concern, and we hope to run 500 WNV 
VecTests in the next three weeks.

Current frequencies of false positives and false negatives in WNV 
VecTest results for oral swabs(a).

Result Type           % (95% Confidence interval)     N
False Negative(b      41.7 (24.5 - 61.2)              24
False Positive        2.1 (1.3 - 3.3)                 869

(a)Relative to RT-PCR results by NYSDOH.
(b)False negatives in American Crow (8), Fish Crow (1), Common Grackle (1).

(NY   07/29/03)


Frequency of false positive(a)  WNV VecTest results from tests of 
oral swabs.(Update 7/29/03)

Species                     % (no. tested)
American Crow               3.1 (227)
Blue Jay                    0.0 (71)
Gray Catbird                5.3 (38)
American Robin              1.3 (80)
Common Grackle              0.7 (144)
European Starling           1.6 (61)
House Sparrow               2.9 (35)
Other Avian(b)              2.3 (213)

All Species                 2.1 (869)


(a)Relative to RT-PCR results by NYSDOH.
(b)False positives in Red-tailed Hawk (1), Mute swan (1), Great 
Horned Owl (1), House Finch (1), Brown-headed Cowbird(1).

Dr. Ward B. Stone BA, MS, Sc. D
Wildlife Pathologist
NYS DEC Wildlife Pathology Unit
108 Game Farm Rd.
Delmar, NY 12054
Phone (518) 478-3032
Fax (518) 478-3035
wbstone@gw.dec.state.ny.us

----------------------------------------------------------------------------
WESTNILEVIRUS-L is an email discussion group for communication and
discussion about West Nile Virus, particularly regarding policy, risk
reduction and public education issues. It is moderated by Dr. Lois Levitan,
Program Leader of the Cornell Environmental Risk Analysis Program.
Subscribers are encouraged to post to the group by sending an email to:
WESTNILEVIRUS-L@cornell.edu.  Postings must be written in plain,
unformatted text, and sent without attachments.  The subject line must
begin with the identifier [WNV-L], followed by a meaningful subject
description.  Archives are posted at:
http://environmentalrisk.cornell.edu/WNV/WNV-LArchiveIndex.cfm.
To subscribe (or unsubscribe), send an email request to
envrisk@cornell.edu. To receive messages once a day in digest
format, subscribers should send an email to listproc@cornell.edu
with message: "set WESTNILEVIRUS-L mail digest-nomime".
----------------------------------------------------------------------------