In recent years reptiles have steadily gained considerable popularity as domestic pets.   With this increase in awareness in reptiles in mainstream society also comes an increase in awareness for reptile conservation and ecology. As a result it is incumbent that zoological parks set high benchmarks for the husbandry and care of these animals that match public perception.

It has been well documented that many species of reptiles pose significant zoonotic risks for people in contact with them but little has been described for commonly encountered Australian species.  Additionally, these pathogens are frequently identified as causing primary disease in these same animals. At Healesville Sanctuary a number of reptiles that pass through the AWHC either enter the collection or end up as surplus animals destined for other organisations. Thus the potential for introduction of disease into captive populations and the risk of human exposure to zoonoses may be high. It is therefore the intention of this project to determine if the commonly encountered captive disease agents Salmonella, Cryptosporidium, Coccidia and Giardia are present in wild populations of reptiles in Victoria.  This is a preliminary study that may, depending on results, lead to future studies targeting more specific species and locations.

Salmonellosis is a disease of humans and animals that occurs as a result of ingestion of the bacteria belonging to the genus Salmonella, within the family Enterobacteriaceae.  Clinical signs of salmonellosis in mammalian patients are related to gastrointestinal upset and include vomiting and diarrhoea.  In severe cases this may lead to anorexia, lethargy, septicaemia and even death.  Reptiles that develop salmonellosis commonly show signs of septicaemia, including pneumonia, coelomitis, hypovolaemic shock, abscesses and osteomyelitis.

Historically in zoological collections keepers, veterinary staff and visitors have been considered to be at risk of being exposed to Salmonella  as it is believed that between 83-93% of reptiles are subclinical carriers of this organism but recent studies on a number of wild reptile populations have found these to be free of actively shedding animals.  Thus it has been hypothesised that one of the major predisposing factors in reptiles developing salmonellosis is immunosuppression due to stress in captivity.  The aim of this study is to compare the serotypes of Salmonella in captive animals to that of wild animals in order to assess the current and past zoonotic risk that these animals pose to the public.  If the serotypes differ significantly it may be inferred that particular serotypes are peculiar to captive situations.

Cryptosporidiosis results in gastro-intestinal disease in snakes and lizards.  Animals can be infected with two species; Cryptosporidium parvum (usually obtained from infected prey items) can pass through the digestive tract of reptiles without causing illness but still poses a significant zoonotic risk to humans.  Cryptosporidium serpentis infection however results in debilitating illness in reptiles without any zoonotic potential. Although no proof exists that infection with Giardia causes disease in reptiles, infection with this ciliated protozoa poses significant zoonotic potential for humans and it is important to establish if wild reptiles can act as vectors for this organism.

Coccidia rarely cause disease in wild reptiles but under circumstances such as overcrowding or stress that may occur with captivity then numbers of coccidia may build to dangerous levels.  Identification and documentation of coccidia species in Australian reptiles is poor and little is known of their pathogenicity but it may be presumed that in high numbers infection can result in clinical disease

Research Aims

This research project will address the following objectives:

1. Determine if Salmonella is present in selected species of wild reptiles in Victoria.
2. Compare serotypes of Salmonella found in wild reptiles with the organisms found in the captive animals at Healesville Sanctuary, Melbourne Zoo, Werribee Open Range Zoo and private reptile collections.
3. Determine if Cryptosporidium is present in selected species of wild and captive reptiles in Victoria.
4. Determine if Giardia is present in selected species of wild and captive reptiles in Victoria.
5. Determine if coccidia are present in selected species of wild and captive reptiles in Victoria and to describe any novel species discovered.