Chytrid or red leg disease is already found on every continent with the obvious exception of Antarctica. The first recorded cases of Chytrid were found in Platannas ( Xenopus laevis which were exported from Africa to the rest of the world and bred by the millions for pregnancy testing in the 1930s. So it is plausible that Chytrid originated from South Africa. Captive bred frogs kept in clean conditions should not have Chytrid. Salamanders and newts are not as likely to carry Chytrid as frogs.