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Disease
Disease is a normal part of the natural world. Most ecosystems
include organisms such as viruses, bacteria, fungi and parasites
that cause disease. Healthy wildlife and ecosystems have evolved
defenses to fend off most diseases before they have devastating
impacts. An ecosystem with lots of variation (genetic diversity
and diversity of species) is more resilient to the impacts of
disease because there are greater possibilities that some species
have evolved resistance, or if a species is lost, there will likely be
another species to fill the niche of an extinct species.
Where ecosystems are not healthy, due to a loss
in biodiversity and threats such as habitat loss, global
warming, pollutants or invasive species, wildlife and ecosystems
are more vulnerable to emerging diseases. Diseases caused by or
carried by invasive species are particularly threatening, as native
wildlife may have no natural immunity to them.
Diseases Threatening U.S. Wildlife
The following are a few of the many diseases threatening U.S.
wildlife:
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Chytrid Fungus: Batrachochytrium dendrobatidis (or “chytrid”
for short), is a fungus that grows on the skin of amphibians,
interfering with their ability to breathe or take up water through
their skin. It has spread across the globe, infecting and
decimating frog populations. It is a global killer of amphibians.
Fibropapillomatosis: Sea turtles worldwide are becoming
infected with this disease, possibly caused by viruses, which
causes tumors to appear on the skin or internally. These tumors
can make it difficult for a turtle to swim, eat or see, and they
weaken immune systems.
White-nose Syndrome: Hundreds of thousands of bats in the
Northeast and Mid-Atlantic states have been infected or have died
from the white-nose fungus. The disease affects hibernating bats,
making them appear to have a white substance on their faces and
wings.
Chronic wasting disease: This disease is a highly contagious,
fatal neurological disease (spongiform encephalopathy) that
infects primarily deer and elk. The disease is believed to be
caused by a modified protein called a prion.
Whirling disease: Trout, salmon and whitefish in 25 states have
been infected by the parasite Myxobolus cerebralis that causes
whirling disease. It damages nerves and cartilage, causing young
fish to die and older fish to swim in a tail-chasing or whirling
motion, making it hard for them to find food and increasing their
vulnerability to predators.
Sylvatic plague: Prairie dogs are highly susceptible to this
bacterial disease, which is transmitted by fleas. The endangered
black-footed ferret is at even greater risk from the effects of the
disease, because not only can it be infected by the disease, but
prairie dogs are also its primary food source