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SALMONELLOSIS

Stephen J. Divers, BVetMed, DZooMed (Reptilian), CBiol, MIBiol, MRCVS

Martin P.C. Lawton, BVetMed, CertVOphthal, CertLAS, CBiol, MIBiol, DZooMed(Reptilian), FRCVS

BCG Newsletter No.136 (July/Aug 2000)

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Printable Copy

There has been a recent upsurge of interest in the press with regard to reptile-associated zoonoses (i.e. human diseases contracted from reptiles), particularly Salmonella. Press releases and announcements have appeared in national papers and magazines by various ill-informed organisations. Several reptile events have been cancelled due to local councils being bombarded with misinformation over the potential risk of Salmonella. As this may affect our members, the following information may be of interest.

The Public Health Laboratory Service (PHLS) and the Communicable Disease Surveillance Centre (CDSC) have provided the following information for England and Wales:

1. In 1999, over 17,250 cases of human salmonellosis were reported and of these only SEVEN cases were confirmed as being contracted from a reptile source. A similar low number of reptile-associated cases were reported the previous year.
2. In 1997 (the latest year for which the PHLS/CDSC have provided complete figures at the time of writing) there were far more cases of confirmed zoonotic disease from domestic animals and their food by-products than from reptile sources:
1. Hydatid disease (Echinococcus granulosus) – an intermediate tapeworm that forms cysts in the liver, contracted from the ingestion of dog/fox faeces: 14 cases.
2. Toxoplasmosis (Toxoplasma gondii) – a protozoan parasite that can cause abortion in pregnant women and congenital deformity in surviving babies, contracted most commonly from cat faeces: 297 cases.
3. Q fever (Coxiella burnetii) – a bacterial infection most commonly contracted by abattoir workers from infected animals: 69 cases.
4. Psittacosis (Chlamydia psittaci) – a bacterial disease contracted from infected birds that can cause pneumonia and death: 322 cases.
5. Toxocariasis (Toxocara spp) – a roundworm parasite that can cause blindness, particularly in children, contracted by the ingestion of dog or cat faeces: 20 cases.
6. Leptospirosis (Leptospira spp) – a bacterial septicaemia that can cause meningitis and renal failure from the ingestion of water contaminated with urine from infected animals, especially rats: 39 cases.
7. Lyme disease (Borrelia burgdorferi) – a bacterial infection transmitted by ticks: 170 cases.

In addition, a scientific paper was presented by Dorestein et al at the recent Conference of the European Association of Zoo and Wildlife Veterinarians in Paris (June 2000). The authors stated that the major Salmonella serotypes that cause human disease are S.enteriditis and S.typhimurium. Indeed, information provided by our own PHLS and CDSC confirmed that of the 17,250+ human cases in England and Wales in1999, 75% were due to these two isolates alone.

Dorrestein and co-workers reported S.enteriditis and S.typhimurium a total of 35 times out of a total number of 1156 Salmonella isolates. In my own small study of Salmonella and reptiles, over 46 different Salmonellae were isolated from reptiles, but S.enteriditis and S.typhimurium were never recovered. While all Salmonellae should be considered potentially zoonotic, the fact remains that S.enteriditis and S.typhimurium are rare in reptiles, and reptile-associated salmonellosis is also, on published accounts, currently rare. It is also possible that where reptiles do possess S.enteriditis or S.typhimurium that such infections are most likely acquired through contact with humans or domestic animal sources, particularly poultry.

Salmonellosis is an intestinal disease that is contracted through the ingestion of faecal (or faeces contaminated) material. It is essential to stress the importance of basic hygiene to avoid disease from any animal; however, there do not appear to be any inherently greater risks associated with the keeping of reptiles than other pets. To prevent problems we would recommend:

1. Simple hand washing using soap and water after handling or cleaning out.
2. Keeping reptiles, their furnishings and associated equipment well away from human food preparation areas.

Those persons at particularly high risk, such as young children, the elderly and the immuno-compromised, should consider taking additional precautions and consider carefully the benefits versus the risks of keeping any animal. We consider the benefits of properly keeping reptile pets far outweigh the potential risks involved. With the current information to hand it appears you are 2,500 more times likely to contact salmonellosis from food than from reptiles!

References:

Bradley, T. and Angula, F.J. (1988). Salmonella and Reptiles: Veterinary Guidelines. Bulletin of the Association of Reptile and Amphibian Veterinarians 8(2): 14

Divers, S.J. (1992). An investigation of Salmonella in a population of 73 snakes (Family Boidae and Colubridae) in the United Kingdom. A UFAW funded research project.

Dorrestein, G.I.M., Buitelaar, M.N., Kik, M., van der Hage, M. and van Leeuwen, W.J. (2000). Salmonella spp in reptiles and evaluation of isolates over the period 1971-1998: Proceedings of the European Assn. Of Zoo and Wildlife Veterinarians, Paris, pp 261-280.