Humans Could Be Contributing to Rabies Outbreaks
in urban areas are creating conditions for skunks to live in close proximity to
one another, leading to more interaction not only with themselves and other wildlife
but also with humans and pets. New research at Northern Arizona University
shows that one unfortunate result could be increased outbreaks of the rabies
understanding of skunk behavior could slow the spread of wildlife rabies in
Flagstaff, Arizona, and other urban areas. In the last decade, Flagstaff has
seen three major wildlife rabies outbreaks among its urban and suburban areas,
with more than 30 cases reported between 2004-2005 and 2008-2009. The record
number of cases has catalyzed research into the causes of these outbreaks.
Tracking skunk behavior
to Dr. Tad Theimer, vertebrate biologist and an associate professor at Northern
Arizona University, the rabies virus had apparently jumped from bats to a new
host in Flagstaff. “Initially, these
skunks appeared to have somehow found a way to keep the virus going independent
of the bats,” says Dr. Theimer, “but now it appears that bats have infected
either skunks or foxes in each of the three rabies outbreaks in Flagstaff. Now we need to understand not only how the
disease is transmitted among skunks once they are infected, but how they are
infected by bats in the first place.” Bats can infect skunks and other mammals,
such as grey foxes, and then the disease can be spread among those mammals and
potentially into domestic cats, dogs, or even humans. This poses a significant
risk to human and pet health.
variety of devices were used to track skunk behavior. These devices included a
combination of live trapping, radio telemetry, and video-camera monitoring. For
example, monitors showed skunks scavenging dead bats. One video captured a mother skunk carrying a bat into
her den where her young likely ate it, displaying one way that rabies could
transfer from one host species to the next. “Not only can the mother skunk now get the disease, but also her
young,” Dr. Theimer explained.
Food and shelter major contributors
second test, which analyzed the transfer of the disease from skunk to skunk, cameras
were placed near cat food dishes and bird feeders in the backyards of resident
volunteers. Yet again, Dr. Theimer and his team witnessed surprising behaviors:
“The number of times we saw skunks biting one another went way up once we put
out cat food. We never saw that kind of interaction with bird feeders.”
to controlling rabies outbreaks in skunks is to stop the problem at its source.
is not the only draw. The abundance of shelter in urban areas has also been a
major contributor to higher skunk numbers as they find safety and warmth
beneath homes. The ability for skunks to access shelter, as well as food, is allowing
skunks to reach much higher numbers in suburban areas compared to the
surrounding pine forests, thereby increasing the likelihood that they will
contract and transmit rabies.
these results provided us with some good evidence that showed how behaviors of
skunks can change, depending on what kind of food and shelter is being offered
and where,” said Dr. Theimer. For example, the research team noticed more
aggressive behaviors as skunks fought for the easily accessible food and
shelter provided by people. And these human influences are what Dr. Theimer believes
could be the primary contributing factor for the rise of rabies outbreaks of
skunks in Flagstaff— especially in the winter and spring months.
Encouraging skunk population to self-regulate
“My goal is to try to get residents to remove
or reduce all human sources of food and shelter [around their homes] so that
the skunk population can self-regulate,” says Dr. Theimer. “Often it is easier
for people to call pest control, rather than fence in their deck or remove all
of their food dishes. What they often forget to realize is that two to three
days later another skunk will move in.” The key to controlling rabies outbreaks
in skunks is to stop the problem at its source.