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DISEASE
Wildlife disease is of great importance to the
health and safety of humans and domestic animals
with 73% of emerging and reemerging pathogens are
known to be zoonotic (transmitted from animals to
people).
There is increasing evidence suggesting that
urbanization and resultant land-use changes
contribute to the emergence of wildlife diseases
through multiple mechanisms, with consequences for
human and pet health.
In light of the increasingly close association
between wildlife and humans in
Cook
County, surveillance and
proactive research is needed to guide and interlink
human health and wildlife management programs with
the goal of limiting the risk of human exposure to
zoonotic diseases.
DISEASE MONITORING AMONG COYOTES IN
COOK
COUNTY
In rural areas, coyotes serve as a host for canine
heartworm, an important parasite for domestic and
wild canids (dogs and their relatives), and to a
lesser extent other domestic animals and even
humans.
 Canine
heartworm is a filarial nematode with a 6-month life
cycle that requires both mosquitoes and canid hosts.
The adult worm is large and resides in the
cardiopulmonary vasculature of its canine host.
The severity of the infection depends on the
number of worms and the length of infection.
Heart infected with heartworm
The parasite is transmitted from an infected canine
to an uninfected canine via a mosquito vector.
Once infected, the ambient temperature of the
mosquito dictates the development of the
microfilaria to the infective L3 larval stage.
Thus microfilarial development only occurs
above a threshold temperature, which becomes the
heartworm transmission season.
Whereas a number of studies have described the
coyote-heartworm relationship for rural populations,
little information is available for metropolitan
areas and sample sizes were limited. As the number
of coyotes in the urban areas continue to increase,
it is possible that prevalence of the heartworm may
also change.
Therefore, we have tested for heartworm in
coyotes within Cook
County
with serology (the study of blood) and necropsy
(postmortem examination).
 We
tested blood samples from 85 radio- collared coyotes
located across
Cook
County.
When we compared our infection rates to
similar data for rural coyotes across the state, we
found that the rate of infection among coyotes in
Cook County was approximately 10 times greater than coyotes
from rural areas in northern
Illinois.
Prevalence of heartworm infection in rural coyotes
across southern, central, and northern
Illinois
(from Nelson et al. 2003) and in urban coyotes in Cook County.
Mange
Mange is a debilitating disease associated with
coyotes and their relatives, especially foxes.
It is transmitted by a mite that infects an
individual and burrows into their skin.
Extreme infection often follows, to the
detriment of the animal, and the animal typically
loses most of their hair and becomes susceptible to
other infections or often succumbs to exposure.
 In
urban areas, coyotes likely serve as the host for
this pathogen, which can also spread to pets and,
rarely, people.
We have been monitoring mange in the
Cook County coyote population since we began
the coyote research in 2000.
A
radio-collared, mange-infected coyote walking across
a driveway in the middle of the day. This animal
died a few days later as a result of the infection
Initially we did not observe mange in
Cook County, but that changed in 2002, and
mange has been maintained at low levels in most
years.
However, in areas where the disease is common, it
has contributed to human-coyote conflicts.
Our results have revealed that
coyotes with
extensive mange infections are not aggressive
(we have yet to record a pet attack by a
mange-infected coyote), but they become more active
during the day and often seek food or cover near
houses, thereby increasing observations by the
public.
Frequency
of mange-related mortalities in coyotes from
Cook
County, by year.
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