If a WC adult, there is little chance of him becoming handleable. Their skin could rip and the tail could also be ripped off.....they "drop" their tail when grabbed as a defense mechanism. The tail grows back, but not as nice looking as the old one. The majority of parasites will be internal and would not pose a threat to other animals unless they came into contact with fecal matter from the infected gecko.....but quarantine is super important when getting any animal, especially a WC one.