Why is that sentence in the middle about pregnancy not elaborated upon or explained in any way? Is the author trying to suggest that their use for pregnancy tests (however effective or ineffective) contributed to their export?
"The chytrid fungus is the main killer of frogs currently. It is thought it was introduced by the importation of African Clawed Frogs who carried the fungus out of Africa. The African frogs were used decades ago to determine if a woman was pregnant. The African frogs carry the fungus but are immune to it. Unfortunately they continue to be sold as pets. Some are released into the wild and spread the fungus to native frogs. They also eat almost anything that moves including native frogs." - Jake Richardson, 10 Animals on the Brink of Extinction, ecoworldly.com, 7 April 2009.