Frog Once Imported for Pregnancy Testing Brought Deadly Amphibian Disease to US

May 15, 2013 — African frogs, originally imported for early 20th century pregnancy tests, carried a deadly amphibian disease to the U.S., according to a new study published today in the journal PLOS ONE.

African Clawed Frogs have long been suspected of introducing a harmful fungus called Batrachochytrium dendrobatidis or Bd to new populations that haven't been exposed to this pathogen before. The fungus has led to the recent decline or extinction of 200 frog species worldwide. A previous study found that the earliest case of Bd in the world was found in African Clawed Frogs in their native South Africa in 1934, but until now no research has tested for the disease among this species in populations that have become established in the U.S.

"We found that African Clawed Frogs that have been introduced in California are carrying this harmful fungus," said SF State biologist Vance Vredenburg. "This is the first evidence of the disease among introduced feral populations in the U.S., and it suggests these frogs may be responsible for introducing a devastating, non-native disease to amphibians in the United States."

From the 1930s to 1950s, thousands of African Clawed Frogs were exported across the world for use in pregnancy tests, scientific research and the pet trade. These frogs will ovulate when injected with a pregnant woman's urine.

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