Diseases and infections are not uncommon in captive and wild reptile and amphibians in New Zealand. They often arise as a result of changes to environmental conditions and interactions between individuals. Some bacteria, such as Salmonella, can be very common in individuals of wild reptile and bird populations and often do not become pathogenic (cause disease) in healthy animals. However in captivity, stress, poor hygiene and interactions with animals from new populations (with new diseases) can reduce immunity and allow those diseases to become pathogenic and result in illness or death.
Some common diseases and conditions observed in captive reptiles in New Zealand are briefly discussed here. Section 8 of the Best Practice Guide to keeping lizards in Captivity provides a more comprehensive analysis of lizard health and care. Diseases and health issues in captive reptiles and amphibians are usually a result of husbandry practices (e.g. stress, overcrowding, temperature and humidity, light, diet).
Note that if you have an issue that requires treatment for a native species, you are required to contact your local Department of Conservation Office in the first instance, as your Wildlife Authority does not allow you to administer or provide veterinary care (you need permission first)!