rapid detection of west nile virus in fox squirrels ... · squirrels, r>0 10/21/2005 q5-233 fox...
TRANSCRIPT
Rapid detection of West Nile virus in fox squirrels ( Sciurus niger) using RAMP® test
Steve SchutzEric GhilarducciDamien ClausonMike McCoy
Uses of RAMP ®
� Rapid screening (same day/next day) of dead corvids (supplemental to PCR testing by CVEC)� Definitive test for crows; other species
testing negative were sent for PCR� Rapid screening of mosquito pools from
unregistered sites (supplemental to PCR testing by CVEC)
Why test squirrels?
� Appear to be susceptible to WNV� Fox squirrels abundant in
residential areas� Definitive indicator of local
transmission� Rapid screening could
provide a new surveillance tool
Methods
� Squirrels submitted by Lindsay Wildlife Museum as part of a collaborative project with Kerry Padgett, DHS� Transported to District lab� RAMP tested oral swabs
following standard corvidprocedures� All squirrels shipped to CAHFS
for necropsy, PCR tests conducted at CVEC
RAMP results: Squirrels
False–False+RAMP–RAMP+Tested
13 R<50(87%)0 R>0(0%)
0 R>50(0%)
1 R>0(7%)
13 R<50(87%) 8 R>0(53%)
2 R>50(13%)7 R>0(47%)
15
Squirrels, R>0
POSITIVE24.7NegativeConcordfox squirrelQ5-23310/21/2005
Negative19.9NegativeConcordfox squirrelQ5-23210/18/2005
POSITIVE>640POSITIVEMartinezfox squirrelQ5-22510/11/2005
POSITIVE19.0NegativeMartinezfox squirrelQ5-21310/4/2005
POSITIVE81.3POSITIVEPleasant Hillfox squirrelQ5-2019/28/2005
POSITIVE33.4NegativeWalnut Creekfox squirrelQ5-1959/26/2005
POSITIVE8.6NegativeConcordfox squirrelQ5-1969/26/2005
PCRRValRAMPCitySpeciesID NumDate
RAMP results: Corvids
False–False+RAMP–RAMP+Tested
16 R>50(24%)5 R>0(7.5%)
>=136 (54%)
31(46%)
67
1/13 (7.6%)
>=122 (71%)
9 (29%)
31
Summary of surveillance results
0.2%(1/419)
63%(27/43)
40% (18/45)
18% (3/17)
PCR
2%(3/149)
47%*(7/15)
46% (31/67)
29% (9/31)
RAMP
Mosquito pools
Squirrels*R>0
JaysCrows
*R>0
How useful was RAMP?
0
2
4
6
8
10
12
31-Ja
n11
-Feb
25-F
eb11
-Mar
25-M
ar8-
Apr22
-Apr
6-May
20-M
ay3-
Jun
17-Ju
n1-
Jul
15-Ju
l29
-Jul
12-A
ug26
-Aug
9-Sep
23-S
ep7-
Oct21
-Oct
1-Nov
# ca
ses
0
10
20
30
40
50
60
70
% p
os
human equine chicken mosquito % pos birds
Conclusions
� RAMP test shows promise for dead squirrel testing� May require modification of cutoff value or test
procedure� Adopting lower cutoff value may also improve
accuracy with jays and other non-crows� Ability to test/respond rapidly made up for
shortcomings� RAMP testing of birds and mosquito pools provided
effective early warning of high risk areas
Acknowledgment
� Kerry Padgett, DHS� Lindsay Wildlife Museum� Gary Bogue, Contra Costa
Times� Lab crew: Damien, Eric, Mike� Field technicians and
supervisors� CAHFS/CVEC