Hmm I was listening to last season and just thought about a theory. Goldrush reminds me of gold mines. And Tanya had a theory that the zmbz came from under ground? Maybe there was some miners that were digging and were exposed to a toxin that infected them. They probably were stuck down there and when they died they decomposed and the gas they released made ground zero?¿?¿?¿? just a guess though. Was I close?