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Lizard parasitology overview



  • All wild-caught reptiles are subject to parisitism.
  • Commonly many captive-born reptiles are subclinically parasitized.
  • In wild animals, internal parasites maintain a homeostasis with the host animal, because the host is essential for the survival of the parasite and a means of transporting future generations of the parasite to suitable areas for transmission to another host.
  • Factors that maintain homeostasis include:
    • The host’s immune system.
    • The dilution of infective stages of the parasite in the environment that the host occupies.
  • Thus, in many cases the captive environment offers a prime opportunity for imbalances in favor of the parasite through the stress and subsequent immunosuppression of the host, and through the increased risk of reinfection of the host due to concentration of infective stages of the parasite.
  • Based on an awareness of parasites in some reptiles, however, some herpetoculturists advocate the prophylactic treatment of all reptiles with antiparasiticides for the more common intestinal parasites.
  • It is interesting, however, that many hobbyists do not prophylactically treat for external parasites:
    • This is perhaps because of an understanding of the potential side effects of pesticides applied to the animals.
    • The side effects of oral deworming are similar.
    • Though some therapeutics may be relatively safe at high doses, the potential effects of killing massive loads of intestinal parasites in an already immunocompromised animal can be severe.
    • In the UK, fenbendazole Fenbendazole is a frequently used anthelmintic treatment for reptilian gastrointestinal parasites:
      • Within the literature there are papers that report adverse effects after administering benzimidazoles, suggesting that the drug may cause immunosuppression. 
      • Administration at 50 mg/kg given for 5 days and then repeated 14 days later, has shown to cause profound heteropenia with transient hypoglycemia, hyperuricemia and hyperphosphatemia in six Hermann’s tortoises. Other studies suggest similar effects in various other species; this emphasizes the need for diagnostic fecal sampling and de-worming only if necessary, rather than just administering an anthelmintic prophylactically.
  • The safer alternative to routine prophylactic treatment of parasites is quarantine Quarantine, serial parasite screening and treatment of specific clinically identified diseases.
  • Techniques for identifying reptilian endoparasites are the same as those for small mammals .
  • Flotation of fresh fecal material in concentrated salt or sugar solutions and wet mount direct smears in saline are essential to screen for reptilian endoparasites.
  • Smaller infective stages of some parasites may only be observed by direct smear.
  • Stains such as Lugol’s iodine solution (5 g iodine crystals and 10 g potassium iodide in 100 mL distilled water) both kills motile protozoans and stains cysts to make identification easier.
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External parasites

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Internal parasites

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Further Reading


Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Tang P K, Pellett S, Blake D & Hedley J (2017) Efficacy of a topical formulation containing Emodepside and Praziquantel (Profender® Bayer) against nematodes in captive tortoises. J Herpetol Med Surg 27 (3-4), 116-122 VetMedResource.
  • Machin R A (2015) Common gastrointestinal parasites in reptiles. In Pract 37 (9), 469-475 VetMedResource.
  • Brames H (2008) Efficacy and tolerability of Profender in reptiles: spot on treatment against nematodes. Exotic DVM 10 (3), 29-34 VetMedResource.
  • Mehlhorn H, Schmahl G, Frese M, Mevissen I, Harder A & Krieger K (2005) Effects of a combination of emodepside and praziquantel on parasites of reptiles and rodents. Parasitol Res 97 (Suppl 1), S64-S69 PubMed.
  • Neiffer D, Lydick R, Burks K et al (2005) Haematological and plasma biochemical changes associated with fenbendazole administration in Hermann’s tortoises (Testudo hermanni). J Zoo Wildl Med 36 (4), 661-672 PubMed.
  • Campbell I & Tzipori S (1982) Effect of disinfectants on survival of Cryptosporidium oocysts. Vet Rec 111 (18), 414-415 PubMed.
  • Holt P E (1982) Efficacy of fenbendazole against nematodes of reptiles. Vet Rec 110 (13), 302-304 PubMed.
  • Telford S R (1971) Parasitic diseases of reptiles. J Am Vet Med Assoc 159 (11), 1644-1652 PubMed.

Other sources of information

  • Šlapeta J, Modrý D & Johnson R (2018) Reptile Parasitology in Health and Disease. In: Reptile Medicine and Surgery in Clinical Practice. Wiley-Blackwell, UK. pp 425-39.
  • Wilson B (2017) Lizards. In: Exotic Animal Medicine for the Veterinary Technician. 3rd edn. Eds: Ballard B & Cheek R. Wiley-Blackwell. pp 95-135.
  • Meredith A (2015) BSAVA Small Animal Formulary. Part B: Exotic Pets. 9th edn. BSAVA, UK.
  • Klingenberg R (2012) Understanding Reptile Parasites. i5 Publishing.
  • Schneller P, Pantchev N & Norden N (2008) Parasitology in Snakes, Lizards and Chelonians. Edition Chimaira, Frankfurt am Mainpp 105-172.
  • Fitzgerald K T & Vera R (2006) Acariasis. In: Reptile Medicine and Surgery. 2nd edn. Elsevier, USA. pp 720-738.
  • McArthur S M, McLellan L & Brown S (2004) Gastrointestinal System. In: BSAVA Manual of Reptiles. 2nd edn. Eds: Girling S J & Raiti P. BSAVA, UK. pp 213.
  • Graczyk T K, Cranfield M R & Bostwick E F (1999) Therapeutic efficacy of hyperimmune bovine colostrum treatment against Cryptosporidium infections in reptiles. In: Proc Annual Meeting of the American Association of Zoo Veterinarians. pp 6-10.
  • Jacobson E R (1999) Use of Antimicrobial Drugs in Reptiles. In: Zoo and Wildlife Medicine; Current Therapy. 4th edn. Eds: Fowler E & Miller R E. Saunders, USA. pp 190-200.
  • Kolmstetter C M, Frazier D, Cox S & Ramsey E C (1997) Metronidazole pharmacokinetics in yellow ratsnakes (Elaphe obsoleta quadrivitatta). In: Proc American Association of Zoo Veterinarians. pp 26.
  • Pare J (1997) Treatment of Cryptosporidiosis in Gila Monsters (Heloderma suspectum) with Paromomycin. In: Proc Association of Reptilian Amphibian Veterinarians. pp 23-24.
  • Cranfield M R & Graczyk T K (1996) Cryptosporidiosis. In: Reptile Medicine and Surgery. W B Saunders, USA. pp 359-363.
  • Frank W (1981) Endoparasites. In: Diseases of the Reptilia, Vol 1. Eds: Cooper J E & Jackson O F. Academic Press, UK.
Reproduced with permission from Bonnie Ballard & Ryan Cheek: Exotic Animal Medicine for the Veterinary Technician © 2017, published by John Wiley & Sons.

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