Frog disease from pregnancy test?
With the South African clawed frog (Xenopus laevis) exported from Africa as a living pregnancy test in the 1930s, the fungus Batrachochytrium dendrobatidis was probably also spread globally, which is now considered one of the most important reasons for the global extinction of amphibians.
After investigations by Rick Speare from James Cook University in Townsville, Australia, and his colleagues on specimens of the amphibian in South African museums, they found traces of the fungus even on almost seventy-year-old collection items. However, since there has been no noticeable increase in the number of cases of disease in the population of the clawed frog since that time, the scientists assume that the two organisms coexisted. In addition, the finds are the oldest evidence of Batrachochytrium dendrobatidis so far, so that this, together with the extensive resistance of the clawed frogs, could explain the original origin of the infection.
During the 1930s and 1940s, clawed frogs were used worldwide as a pregnancy test. For this purpose, the urine of women was injected under the skin. If the woman is expecting a child, the hormones in the urine stimulate the female frog to ovulate. Male animals, on the other hand, produced sperm in response to the hormone gonadotropin. With the thousands of amphibians intended for this purpose, however, the fungi arrived as stowaways in ecosystems that were new to them and whose species had not yet been able to develop protective mechanisms.
Globally, more than a third of all amphibian species are threatened with extinction. In addition to Batrachochytrium dendrobatidis, habitat destruction, illegal hunting, pesticide contamination or increased UV radiation are responsible for this. The latter also weaken the animals' immune systems, making them more susceptible to diseases.