Plague Surveillance by Serological Testing of Coyotes (Canis latrans) in Los Angeles County, California Author(s): Chinwe U. Thomas and P. Eric Hughes, Source: Journal of Wildlife Diseases, 28(4):610-613. Published By: Wildlife Disease Association DOI: http://dx.doi.org/10.7589/0090-3558-28.4.610 URL: http://www.bioone.org/doi/full/10.7589/0090-3558-28.4.610

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SHORT

COMMUNICATIONS of Wildlife

Journal

Diseases, Wildlife

©

Plague

Surveillance

(Canis

latrans)

by Serological

in Los Angeles

Testing

County,

28(4),

Disease

(Canis

Sera from collected

latrans)

19 (5.6%)

of 338

in Los Angeles

coyotes

County,

California between 1986 and 1990 had antibodies against Yerslnla pestis using the passive hemagglutination test. Coyotes were excellent sentinels of plague activity in Los Angeles County. Enzootic plague declined dramatically in the county during the 5-yr period. Key words: Plague, Yersinia pestis, coyote, Canis latrans, serological survey, prevalence, carnivores, Los Angeles County.

Over in the

90%

of

United

human

States

plague

occur

in the

(Centers for Disease Control, 1965 to 1989, 9.4% of human reported in the United States California.

Three

cases

of

with

California beecheyi,

plague

manus) mophilus

montanus beecheyi

California

plague

(Willebeng

and Gnesbnink, Coyotes (Canis

in

1982;

Von

1990). appear

transmission et

testing of coyotes can tent of plague activity

al.,

1976),

squirrodents

directly

1979).

We

sion

among

(Wi!leberg

et

population

of

ment uary tested

Sperto be

al.,

(Howell,

1982).

de-

Coyotes by ingestbitten by

junct

the

to their The sex

were

separation

(Barnes,

The kept

help define the exin rodent prey pop610

Depart1 Janwere Blood

pest

abatement

activities

in

and

Los

capture location, and approximate

of ad-

Angeles

date of subage (adult

juvenile) of the coyotes were recorded. adult was defined as a coyote estimated be 1-yr-old on olden. Blood was collected cardiac puncture immediately after the

coyotes

serological

County

by personnel agencies as an

routine

control

County. mission, or An to by

Angeles

were collected city and county

animal

Hopkins

Los

of Health Services, between 1986 and 31 December 1990 for antibodies to Y. pestis.

samples various

1982; Nelson et a!., 1986). latrans) are a common

plague Reyn

ground testing

their fleas (Von Reyn et al., 1976; Thomas et al., 1989). Coyote sena submitted to Comparative Medical and Veterinary Services, a divi-

plague

nonmigratory wildlife species living in close proximity to human populations in many areas of the southwestern United States. Although coyotes are rarely involved

ulations such as California rels more efficiently than

become infected with Y. pestis ing infected rodents or by being

Spermophilus Oropsylla (Dia-

1979;

Medical

coyote

human

et al.,

Comparative

southwest

a reservoir of plague, but serves as an amplifying host (Nelson et al., 1986). Wild carnivores are excellent sentinels for

1992

to 34#{176}50’N, 117#{176}40’to 118#{176}55’W). Many parts of the county have a considerable

1988). From plague cases occurred in

(Barnes, does not

Association

infections

epizootics

ground squirrels, and their fleas,

610-613

scribe the findings from a 5-yr serological survey of coyotes in Los Angeles County, California (USA). Los Angeles County encompasses more than 10,000 km2 and consists of 163 cities and unincorporated communities (33#{176}40’

have occurred in Los Angeles County, California since 1978. The majority of human cases in California are epidemiologically associated

pp.

of Coyotes

Chinwe U. Thomas and P. Eric Hughes, Los Angeles County Department of Health Services, and Veterinary Services, 12824 Erickson Avenue, Downey, California 90242, USA

ABSTRACT:

1992,

shot, tubes

and

submitted

within

sera were centrifuged, frozen until tested.

tion

1 antigen

cells

used

and

in serologic

in serum

72 hr of collection. The

extracted plague

sensitized tests

and Frac-

red were

blood

supplied

SHORT

1.

TABLE

County,

Prevalence

of antibodies

in coyote

sera

from

select

communities

Number

Community

Number positive’

tested

Capture

dates

seropositive

6

29

Park

in Los

Glendale

Serum

by

3

25

Sunland

“Two

4

17

1986

32

Oct

1986

32

32

Dec

1986”

64,

32

1987b

32,

16

Mar

1986

16

1987h

32,

2

Apr

1

Jul

La Canada-Flintridge

4

1

Aug

San

3

1

Sep

by the

the

passive

coyotes

Centers

hemagglutination

for

Disease

Control

Senopositive

(Fort

USA). Passive hemagand hemagglutination

(HI) tests were used to detect of plague antibodies in coyote methods of the World Health

Organization ter 1:16

was

(1970). A serum antibody ticonsidered positive. Serum

in evidence prevalence

titer

less

than

P = 0.0107) where in

was

con-

Griffith

PHA

titer

Chi-squane tests or were used where approanalyses (Dean et a!.,

1990). Sera from 338 coyotes were tested for antibodies to Y. pestis during the 5-yr period. Adult coyotes comprised 75% of those tested. Nineteen coyotes (5.6%) had serum antibody titers 1:16 according test. Three juvenile coyotes itive

[Griffith

geles 32)].

(1:16) and Nine (5.6%)

nine (5.8%) positive for

Park

(1:32),

to the PHA seropos-

City

of Los

An-

La Canada-Flintnidge of 161 male coyotes

of 155 female plague antibodies.

coyotes for which was seropositive.

were

the

sex was

coyotes One not

(1: and were of 22

recorded

Los

Angeles of plague was sig-

nificantly higher in coyotes from Griffith Park (20.7%) (Fisher Exact test; P =0.0029) and Glendale (23.5%) (Fisher Exact test;

below

positive

in

sites during and unincor-

communities

titer

by

detected

sample cities

had serological 1). Serological

PHA test If the HI

PHA

were

the Eight

porated

by the HI test.

the

of

County (Table

to be positive tested with the the

32

coyotes

only one-third the 5-yr period.

determined was then

nonspecific. exact tests in statistical

32

1989 1988

test (PHA).

inhibition the presence sera using

two-fold,

32

32

1989

in month.

Colorado, (PHA)

was

64

Jan

4

Collins, glutination

sidered Fisher priate

64,

1987

5

1:16

32

128

1986”

Burbank

seropositive

32

May

Glendora

Marino

32

Dec

1

City

of titer

Inverse

Aug

16

Angeles

titer

Angeles

for

coyotes

Mar 1987 Apr 1987 Apr 1988 Oct 1988

Los

611

1986-90.

California,

Griffith

pestis

to Yersinia

COMMUNICATIONS

the

than in coyotes captured county. Positive sera

Park

gust 1986 nopositive

were

Serological the

square coyotes of 89 (4.8%)

a 2-mo-period 1987). prevalence

county

over

sewere

(December steadily

the

Aufour

5-yr

declined

period

(Chi-

test; P = 0.013). Seven of 50 (14%) tested in 1986 were senopositive; 7 (7.9%) coyote sena in 1987, 3 of 63 in 1988, 2 of 59 (3.4%) in 1989 and

0 of 77 (0.0%) plague antibodies. Serological (17.4%) and itive coyotes tured Griffith

between

and October 1988. All coyotes from Glendale

submitted over 1986 to January in

collected

elsefrom

in

1990

prevalence December submitted

in Glendona in Park in 1987

were

positive

peaked (12.5%). in April 1987 (n =

for

in April Seroposwere cap-

(n = 2) and 1) and 1988

in (n

612

JOURNAL

OF WILDLIFE

DISEASES,

VOL. 28, NO. 4, OCTOBER

1992

time

(Willebeng

et al.,

Barnes, 1982). Plague-endemic terns

of

foci

activity.

survey

of

1979;

For

carnivores

Christie,

have

distinct

example, in

1982; pat-

in a large

Oregon

from

1974

to 1979, the highest serological prevalence occurred in June (21.7%) and the lowest rates were seen in December (3.0%) (Hopkins

Jan

Feb

Mar

Apr

May

Jun

Month

1.

FIGURE

Angeles 1986

Prevalence

agglutination

=

of

test

each

Sep

Oct

Nov

Dec

of plague

(PHA)).

antibodies latrans) by

Sample

by

the size

in Los month,

passive

hem-

is indicated

four

positive

December

sena

were

submitted

collected

dur-

from

two

Gresbnink,

contrast in Los

the methods fered from up 81.5% strips

at

bar.

1). The

ing

Aug

County coyotes (Canis 1990 (serum titer 1:16

to

top

Jul

of Submission

and

!ences coyotes

titer

and

antibodies. reports

1).

et a!., 1989). otes, Barnes

titers detected 1:16 to 1:128.

in

this four

preva-

collection and as 1:32 or great-

the minimum positive analysis, we found no the month of sena co!-

serological

areas, Sunland (n = 2) and Glendale (n = 2) in 1986. All coyote sena collected in February (n = 19), June (n = 17) and November (n = 43) during the 5-yr period were negative for plague antibodies (Fig. Serum antibody study ranged from

used for blood was defined

en. Using 1:32 as titer in a separate association between lection

These

used in the Oregon study difthis study in that coyotes made of the sample, Nubuto paper

were

a positive

1982).

with those determined for Angeles County. However,

prevalence

This finding that hemagglutinating

of plague

is consistent with antibodies

persist for more than 10 mo in domestic dogs (Rust et al., 1971) and at least 2 mo in black bears (Ursus americanus) (Cloven In a serological (1982) found

that

study of coyhemagglu-

of the 19 seropositive coyotes had titers greater than 1:32. The highest titer (1:128) was detected in a female coyote in Griffith

tinating antibodies became detectable in 8 to 14 days, generally peaked in 20 to 30 days and diminished to undetectable levels within 6 to 8 mo. Persistence of serum

Park

were

antibody

from

of organisms

found

in October in

each

Sunland in male coyote

of

same as that in Los Angeles

male

serological in this reported County

1985 (Nelson et rological prevalence

positive

Titers

two

of

1:64

coyotes

December 1986, and in one from Glendale in December

1986. The overall 5.6% in coyotes

ty during based on

1988.

Only

the our sera

al.,

5-yr

prevalence survey

for wild carnivores from 1978 through 1986). declined

However, in the

past 5 yr (1986 findings. Similarly, were

of is the

detected

in the

to

secoun1990), fewer ground

squirrel populations in Los Angeles County; only one seropositive ground squirrel was reported in Los Angeles County in 1990 plague

(Smith activity

and

Wilson, typically

1991). fluctuates

Sylvatic over

titers

may

depend

initially

on the

ingested

number

and

the

cu-

mulative effects of repeated infection (Messick et a!., 1983). The presence of Y. pestis, as determined in this survey, is affected by plague antibody persistence and such data should not be used for risk assessment. Plague appears from previously

to have seropositive

Angeles

County.

sampled the degree

in this study of participation

ping

agencies

disappeared areas of

However,

in the

were

the dependent by various

surveillance

Los

coyotes on trap-

program

and the location within Los Angeles

of trapping activities County. In recent years,

more coyotes in the county

been had

in the

past.

have that This

shift

tested from areas not been sampled

in testing

areas

(sam-

SHORT

pling

bias)

decline otes;

may

partially

in the overall

of seropositive

coy-

may

been

testing

have

the

5-yr

prevalence

data

well with of plague

period.

report-

for for

the

laboratory reviewing

ious city ed coyote

Any

Centers

for

support, Dr. this manuscript,

and county sera.

plague A draoccurred

Los

in southwestern

Dr.

Tom

provid-

A.

M.

1982.

Surveillance

control

FOR

DISEASE

CONTROL.

1988.

Human

States, 1988. Morbidity and Report 37: 653-656. CHRISTIE, A. B. 1982. Plague: Review of ecology. Ecology of Disease 1: 111-115. CLOVER, J. R., T. D. HOFSTRA, B. G. KULURIS, M. T. SCHROEDER, B. C. NELSON, A. M. BARNES, AND G.

BOTZLER.

1989.

Serologic

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pestis infection in small mammals and bears from a temperate rainforest of north coastal California. Journal of Wildlife Diseases 25: 5260. DEAN, A. D., J. A. DEAN, J. H. BURTON, AND R. C. DICKER. 1990. Epi info, version 5; a word processing, database, and statistics program for epidemiology on microcomputers. Centers for Disease Control, Atlanta, Georgia, 383 pp. HOPKINS, D. D., AND R. A. GRESBRINK. 1982. SurYersinia

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(Onychomys

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L. G.

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in

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interface

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report,

nia,

CITED

the

21-23.

of

fleas,

of

Infectious

SMITH,

problem of

88-96.

MARSHALL.

mental

coyote

Idaho.

in

Proceedings

of

SMITH,

rodents,

12:

seroPublic

1-6.

ecology

imals

C. Patrick Ryan and the var-

10:

testing

J. H., D. C.

Control

that

19:

ence RUST,

urban

B. C., M. B. MADON, complexities at the

D.

Disease

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plague

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Oregon Journal

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in

American

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NELSON,

in-

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613

1295-1297.

G.

Diseases

of

substantial

agencies

LITERATURE BARNES,

72: R.

MESSICK,

that obtained surveillance.

epizootic in the county. We thank George Matsumoto, and

Health HOWELL,

in

sylvatic

carnivores.

tebrate

in serological prevalence signal the development

Q uan

of

testing

in nonendem-

are efficient sentinels in Los Angeles County. decline in plague activity

during

veillance

recent

number

ed here correlates from other methods

crease may

the

prevalence

diluted by increased ic areas. The serological

Coyotes activity matic

explain

COMMUNICATIONS

on

Plague.

Report Geneva,

23-25.

publication

21 August

Passive

Health

1991.

OrgaWorld

Series 447, Switzer-