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Chytrid Fungus (Batrachochytrium dendrobatidis)
Photo credit: AJ Cann,

Chytrid Fungus

(Batrachochytrium dendrobatidis [Bd])

Report this Species!

If you believe you have found this species anywhere in Pennsylvania, please report your findings to state and federal authorities immediately!

Species at a Glance

The fungus “Bd” is a member of a phylum of primarily aquatic fungi called Chytridiomycota, some of which are parasitic. Bd infects living amphibians (primarily frogs) and causes the disease known as amphibian chytridiomycosis. This disease is believed to be a major cause of global amphibian declines and extinctions.

Similar Species

A second species of Batrachochytrium, B. salamandrivorans (Bs), has emerged as a new amphibian disease agent affecting salamanders in Europe. The U.S. Fish and Wildlife Service has banned the importation of salamanders from Europe to prevent introduction of this disease organism to North American salamander populations.


The chytrid fungus is currently found on every continent where amphibians exist and is actively spreading to new populations.


Note: Distribution data for this species may have changed since the publication of the Mid-Atlantic Field Guide to Aquatic Invasive Species (2016), the source of information for this description.

Environmental Impacts

This disease interferes with essential processes that allow amphibians to take up water through their skin to breathe. Infected frogs may become lethargic, they are often unable to right themselves if turned upside down, and they may jump or swim in circles. In addition, the skin appears bloodshot and they may sit out in the hot sun when healthy frogs would seek shelter. Some species of frog, such as the African clawed frog, appear resistant to the disease, although they can still be carriers and move the fungus to new locations.

*For information on how to prevent the spread of "Bd", be sure to view information provided on the "Clean Your Gear" page.


Information for this species profile comes from the Mid-Atlantic Field Guide to Aquatic Invasive Species (2016).

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