Chytridiomycosis is an infectious disease of amphibians. They are caused by the chytrid "Batrachochytrium dendrobatidis". Chytridiomycosis is believed to be one of the many reasons why amphibian population is declining. They have also made many species extinct. The fungus is capable of causing deaths in some amphibian populations and 100% mortality in others. There is no cure. The fungus has decreased the amphibian population by 30% worldwide.