Journal
Serosurvey of Selected from Oklahoma Jeremiah
T. Saliki,13 Oklahoma Boulevard,
Laboratory, N.
Lincoln
Sandra
State
Viral and Bacterial
J. Rodgers,1
University,
Oklahoma
Diseases, © \Vildlife
Diseases
and
Gene Eskew,2 Oklahoma 74078, Oklahoma 73105, USA;
.34)4).
1995. pp. Asuxiation
Disease
1998
in Wild Swine
Oklahoma Animal Disease Diagnostic USA; 2 Department of Agriculture, 2800 and Corresponding author (e.mail:
1
Stillwater,
City,
of %Vildltfe
[email protected]).
Blood
ABSTRACT:
collected
samples
from
wild swine (Sus scrofa) in thirteen (USA) counties during 1996 were tibodies against six viral and two eases.
No
antibodies
to
120
mission
Oklahoma
tially
tested for anbacterial disbrucellosis, pseu-
swine
swine the
dorabies, sicular to one in 44% serovars
transmissible gastroententis, and yestomatitis were detected. Antibody titers or more leptospiral serovars were found of the samples, the two most frequent being Leptospira interrogans serovars bratislava (29%) and pomona (27%). Antibody against
porcine
part’ovirus
was detected respectively.
virus
swine, positive
for
porcine
reproductive
and
in
17%
Two
antibody
to
and
(2%)
recently
from
porcine
Although
syninfluenza,
dated
time
eases. survey
suis), porcine ra interrogans
exposed
to
Brucella
suis
parvovirus (PPV), (L. interrogans),
Leptospi-
and
(Clark
and 94#{176}58’ to chosen because
Corn
et a!.,
1986;
area
New
et a!., 1994; Pirtle et a!., 1989; Stallknecht et a!., 1993; van der Leek et a!., 1993a, b; Zygmont et a!., 1982). The domestic swine population in 595% between Cole, has
1997). been
operations, number
While due
of
operations contact
Oklahoma 1991 and most
to
feral
of
this
large-scale
Oklahoma small-scale that
with
has increased 1996 (Bloyd
could swine.
by and
Between
potentially A two-way
No
get
in
trans834
Coal,
and
Roger
was
and
(PRRS).
The
restudy
33#{176}48’to 36#{176}05’N
100#{176}00’W. This area was most of the recent expanoperations
occurred
and
serum
was
separated
until
used.
The
of these and
sera
from feral
regarding
county
1996,
tubes
(7-mo-old)
collected per
there
of obtaining region.
December
in clot
adult
data
to
Kiowa,
reproductive
January
distribution
diswas
Oklahoma
Pontotoc,
collected
apparently
a large swine
emerged
Choctaw,
between
swine
was
the most
study
because of the possibility from feral swine in that
blood
increase
commercial
still harbors “backyard”
in
and sera
and,
thirteen
syndrome is located
sion
expand
Jefferson,
porcine
spiratory
1983;
it up-
1) for evidence of exposure to diseases, including the recent-
ular stomatitis virus (VSV) New Jersey serotype in various parts of the United States et a!.,
to
this
Hughes,
Oklahoma, (Fig. swine
ly emerged
vesic-
in
disparts be
base newly
Caddo,
Grady,
Mills) eight
(B.
time
of
(Bryan,
Custer,
pseu-
to
swine
swine
in various documented,
etiologic
objective
feral
Logan,
been
been
destroy(Stevens,
information
to include
The
of
swine is well this
and
importantly,
populations
(PRV),
have for
occurrence
that
from
counties
have
presum-
transmission
swine
in feral states
is important
homa (USA), with two high-density areas in the southcentral and southeastern regions (Stevens, 1996). Some wild swine virus
disease
domestic
the
ease agents of the United
swine (Sus scrofa) are widely disin the southern one-half of Okla-
dorabies
for
is and
(Stevens, and,
as part of the justification feral swine in Oklahoma
geographic Feral tributed
contacts
of
1996).
parvovi-
swine
to
poten-
domestic the size
frequently
such
potential
wild
used ing
syndrome
respiratory
the
might and
swine population between feral
occur
Indeed,
ably,
were
feral contacts
swine
1996).
virus.
Key words: Leptospirosis, rus, porcine reproductive drome, serosurvey, Sits scrofa, vesicular stomatitis.
feral Although
domestic
emerged
respiratory
diseases
Oklahoma unknown,
still
swine influenza and 11% of the
samples the
of infectious occur between populations.
stored were
120 swine.
the
sex
swine. at -20 tested
or
The C for
SHORT
done
using
lysis
test
the
microscopic
(MALT)
agglutination-
(Cole
et a!.
terial seed stocks for the serovars were obtained (Ames,
Iowa,
835
COMMUNICATIONS
USA)
1973).
,
Bac-
six L. interrogans from the NVSL
and
cultured
in
our
laboratory prior to use in the MALT. Samples giving titers of 100 against one or more serovars were considered positive for 1.
FIGURE
sera
swine
Oklahoma
were
counties
from
leptospiral which
feral
antibody.
Pseudorabies antibody was detected ing the commercial semi-automated
collected.
agglutination
antibodies productive
against B. suis, respiratory PRy, swine
(PRRSV), (SIV),
transmissible
(TGEV),
PPV, porcine resyndrome virus influenza virus
gastroenteritis
VSV New Jersey and L. interrogans
rotypes, tislava,
canicola,
and
Indiana serovars
and
or
pomona.
and
negative
ommended
sebra-
hardjo, Seven
grippotyphosa,
terohernorrhagiae,
Tennessee,
a!., 1996)
virus
(Viral
test
Memphis,
sera based
cutoff
USA)
icof
1996)
serotype
Ames,
index
value
H1N1
et
test
(Cher-
SIV A!swine/Iowa/31
(obtained
USA)
Inc.,
of 8. A hem-
(HI)
utilizing
Iowa,
Antigens, (Rodgers
were scored as positive on a manufacturer-rec-
agglutination-inhibition nesky,
uslatex
from
was
used
the
NVSL,
to detect
SIV
the disease agents were chosen because of their importance in domestic swine populations in Oklahoma as indicated by the frequency of requests for diagnostic ser-
antibody at a screening dilution of 1:5. Detection of PRRSV antibody was done using a commercial ELISA kit (Idexx Laboratories, Westbrook, Maine, USA) according to
vice, and VSV if feral swine
the sults
disease swine. The
was included to determine might be a reservoir for
that
is
standard
tech,
Inc.,
not
present
card
agglutination
Pomona,
in
domestic
(S/P)
test
California,
(V-
USA)
used for B. suis, with sera being positive or negative. An indirect
a
was
scored as fluores-
cent antibody test (IFAT) was used for PPV and TGEV at a screening dilution of 1:5. The PPV reagent slides were prepared
0.4) (SP (Yoon
manufacturer’s being expressed ratio.
All
instructions, with as a sample/positive
ELISA-positive
as well borderline ratio 0.2-0.39) were et
a!.,
1992),
in
determining the antibody animal. Testing for VSV
sey,
body
described staining vovirus
following
a method
for bovine viral diarrhea (Corapi et a!., 1990). Porcine seed stock and PK-15 cells
obtained
from
the
National
Services Iowa,
USA).
Laboratories The TGEV
tained
from
a commercial
tive.
at
1:5
Leptospira
dilution
(NVSL) slides
(Ames, were ob-
source
were interrogans
IFAT parwere
Veterinary
Inc., Pullman, Washington, showing a distinct intracellular cence
previously
(VMRD, USA).
scored testing
Sera fluoresas posiwas
ratio
reaction re-tested
samples by IFAT
a titration
format
starting at 1:20 dilution, using spot slides (Corapi et a!., 1990) containing MARC145 cells (NVSL, Ames, Iowa, USA) infected with the VR-2332 strain of PRRSV (ATCC, Manassas, Virginia, USA). The
using PPV-infected porcine kidney (PK15) cells spotted onto teflon-coated slides (Gel-Line associates, Newfield, New JerUSA)
(S/P
re-
IFAT
result
was
was
considered
performed
Iowa, USA) using (Katz et a!., 1995). Table 1 summarizes
definitive NJ
status and
of IN
at the NVSL
each anti-
(Ames,
a competitive the
in
ELISA
results
obtained
for the eight disease agents. All 120 samples could not be tested for antibodies against all eight infectious agents because of insufficient quantities samples. Evidence of the
eight
infectious
the
most
prevalent
gans
(44%)
followed
of sera exposure agents
agent by
for a few to four of
was was PPV
detected; L.
interro-
(17%),
SIV
836
JOURNAL
I.
TABLE
OF WILDLIFE
Serologic
test
DISEASES,
results
for
VOL. 34, NO. 4, OCTOBER
antibodies
against
selected
1998
diseases
in Oklahoma
feral
swine.
Positive I)isease
Bntcella
Test
agent
Card
sp.
Leptospira
tirus
tested
Number
%
120
0
0
117
52
44
117
20
17
117
2
1.7
Autolex
120
0
0
ELISA,
virus
Pseudorabies
test
IFAT
parvovirus
PHHS
agglutination
MALT
interrogans
Porcine
Sera
method(s)’
IFAT
HI
117
13
11
TCEviriis
IFAT
117
0
0
VSV
c-ELISA
109
0
0
Swine
See
influenza
text
hr
virus
abbreviated
(11%) and of occurrence
PRRSV of
scending
order: hardjo,
from Of
17%;
suis,
none
The to
tested
to 6,400. 120 sera were
frequencies the six
were,
tested
when
de-
swine
for
and
B.
of the
two
agents. Similarly, none of the 117 and 109 tested for TGEV and VSV, respectively, were positive. These results are surprising, especially for B. snis, and PRV for which antibody prevalence rates varying from 3% to 23% and from 8% to 36%, respectively, have been found in some feral swine populations in other parts of the United States (Corn et a!. 1986; Pirtle et a!., 1989; van ,
der Leek et a!., 1993a, 1982). Our failure to Brucella-positive wild from and
(1) efforts brucellosis
ing,
as evidenced
b; Zygmont et a!., detect any PRVor swine may result
to eradicate in Oklahoma by
pseudorabies are succeed-
the
state’s
recent
re-
classification from stage IV to stage V in the national PRV eradication campaign; (2) the sera tested were not from a random sample and may thus not be representative of the feral swine population, or (3) a corollary might
to the currently
tion
that
that sure
used in to detect
Indeed,
above be
a sample
in the
is that so rare size
much
both in the
larger
this study is required at least one positive past
we
have
diseases popula-
detected
than to be animal. PRV-
has the
data).
is important nation test for for
ranged
PRV any
ic-
1%.
canicola, titers
PRV from
unpubl.
7%;
for
positive
L.
pomona,
grippotyphosa,
feral
positive
in
29%;
3% and antibody
leptospiral 100 the
tests.
bratislava,
terohemorrhagiae,
Positive
of
(2%). antibodies
serovars
interrogans
23%;
names
pigs
in
been same
detected in domestic study area (J.T. Saliki,
In
regard
to
studies
B. suis,
it also
to note that the card agglutiused in this study was designed
B. abortus and B. suis antibody Regarding TGEV,
mation
follow-up
on
its
might be problematic detection. no published infor-
seroprevalence
in the USA same caveats
in
was available. listed above
and its possible occurrence in Oklahoma may not be basis of this is different
study. since
The VSV
wild
swine
However, the apply to TGEV in feral excluded
situation has not
swine on the
with been
VSV ob-
served in Oklahoma for over 20 yr. Hence, its absence in the feral swine population is not surprising. The recent recrudescence in VSV has included two states bordering Oklahoma (New Mexico and Colorado) but
results
of
intensive
monitoring
domestic swine, horse tions indicate that this
and latest
not
(G.
involve
Oklahoma
data). Previous ous serovars distributed parts lence mals firm the
sampled
against
those 117
the
Eskew,
unpubl.
studies have shown that variof L. interrogans are widely among feral swine in different
of the USA, rates ranging
a!., 1986;
of
cattle populaflare-up does
(Clark
with from et
antibody 22-87% a!.,
New et a!., 1994). results by finding feral
at least
hogs one
tested serovar
prevaof ani-
1983;
Corn
et
Our data conthat 44% of had
antibodies
of L.
interro-
SHORT
gaits.
Interestingly,
bratislava frequently
interrogans
pomona
are
detected
mestic
swine
ratory L.
L.
and
serovars
samples
(J.T. titers
44% (:s5)
a single
ers, swine
that
might
have
one serovar cross-reactive
been
populations
in
Park (USA), of 14% (New of
of SIV
antibody
only
Oklahoma.
wild mined.
health
In
and
SIV
it is not known
ELISA
tance tion. has
PRRSV
and
IFAT,
of of
the PRRSV
Indeed, been
in
found
report
population. of
tion
in wild
swine.
for PRRSV there
that these could swine
J.
the
is
this two
might
is the infec-
tests
were
detection be
80
a size-
PRRSV
Although
a slim
in this chance
be false positive reactions.
isolation
specimens
L.,
of PRRSV can
definitively
from
wild
confirm
AND
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\V
L.
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(eds.).
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the
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the
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ricultural
had
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B. L., AND
BLOYD,
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2 or more of samples
infected test
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recently
Our
56%
of
been
but the antibodies.
Serological has
most
PRRS
LITERATURE
52
latter group had a very high against one serovar than the indicating
of
do-
serovar
against (61%)
occurrence populations.
swine
labo-
Of the
samples,
against
the
most
our
data).
had positive titers serovars. A majority
in the (4-fold)
in
unpubl.
Saliki,
the among
tested
interrogans-positive
positive
serovars
also
837
COMMUNICATIONS
NI.
SACKS,
III.
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virus
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