African Clawed Frog Carries Deadly Amphibian Fungus
Researchers at the San Francisco State University have found that African Clawed Frogs, which were originally imported to the country for early 20th century pregnancy tests, carried along with them a deadly amphibian disease. They have long been suspected of introducing a harmful fungus.
The finding was published in the journal PLOS ONE. The researchers claim that the African Clawed Frog carried a harmful fungus known as Batrachochytrium dendrobatidis or Bd to the new populations that weren't exposed to it.
This fungus has led to a great decline in the frog species. It has led to the extinction of nearly 200 frogs species worldwide. The first case of Bd was seen in African Clawed Frogs in their native South Africa in 1934, but no study was done to test this disease among species that have 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 in a press statement. "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."
On being injected with a pregnant woman's urine, these frogs ovulate. Thousands of these frogs were exported across the world for use in pregnancy testing.
At present, these frog populations can be spotted in urban areas. Researchers predict they are present in these areas because they were released by the hospitals into the wild when new pregnancy testing methods were invented.
On being infected with Bd, these frogs can survive for long periods of time without dying, increasing the chances of passing the disease to more species.
Researchers are surprised to find that these frogs still exist after more than half a century of being brought to the U.S. This clearly states that there is a stable relationship between the pathogen and the frog. At the same time, another frog specie known as Sierra Nevada was killed by this pathogen.
In the current study, Vredenburg and colleagues tested museum specimens at the California Academy of Sciences. By wiping the DNA from the skin of the preserved African Clawed Frog specimens that were collected from the wild population in California, they checked for the prevalence of the disease.
Apart from this, they also tested the specimens collected in Africa and spotted the evidence of Bd present in the indigenous population.
African Clawed Frogs are no more used in pregnancy testing, but are still imported for various biomedical and basic science researches. However, nearly 11 states in the U.S. have restricted the importation of these frogs because of the pathogens they carry.