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Chelonia parasitology overview



  • Chelonians can be affected by a wide range of parasites.
  • Endoparasites are frequently seen in captive chelonians, however their clinical significance is controversial.
  • Nematodes Oxyuriasis: chelonia, trematodes and cestodes jave frequently been reported in chelonians, particularly wild-caught animals.


  • Oxyurids (pinworms) are frequently observed in the feces of chelonians and are usually of little or no pathogenic significance Oxyuriasis.
  • Some authors state that in low numbers, oxyurids may have beneficial effects in stimulating gastrointestinal motility and aiding cellulose digestion.
  • Other authors speculate that high burdens may predispose to rectal prolapse, obstruction, anorexia Anorexia and death.
  • The life cycle is direct and reinfection is via the oral-fecal route.
  • Anthelmintics are often administered if moderate numbers are found. It is also essential to address the environment to prevent reinfection.


  • Ascaridoid nematodes (Angusticaecum spp) are frequently observed in captive chelonians.
  • Diagnosis is by identification of the thick walled ova or adult nematodes in the feces.
  • Affected animals are often asymptomatic.
  • Some authors state that gastrointestinal obstruction Gastrointestinal obstruction may occur in smaller individuals, particularly after anthelmintic treatment. Intussusception, ulceration, coelomitis and thromboembolism have also been implicated with ascaridiasis.
Treatment options for oxyurid and ascarids
  • Fenbendazole Fenbendazole:
    • Various dose ranges have been published, including:
      • 50-100 mg/kg PO as a single dose, and then repeated as a single dose 14-28 days later.
      • 50 mg/kg PO for 3 consecutive days. 
      • 100 mg/kg intracolonic at a one off dose.
    • Oxfendazole Oxfendazole: 66 mg/kg PO; repeat once in 14 days.
    • Emodepside (1.98%) and praziquantel Praziquantel (7.94%) (Profender, Bayer): 1.12 mL/kg applied topically on thin skin such as the neck of chelonians.
  • Environmental control and strict hygiene is necessary to reduce reinfection rates.
Ivermectin must NOT be administered to chelonians.
Benzimidazole-associated morbidity and mortality has been frequently reported so treatment should always be based on diagnostics and observation of a significant number of internal parasites.


  • Animals are often asymptomatic.
  • High burdens may cause secondary malnutrition and enteritis.
  • Diagnosis is based on observation of cestode ova or proglottids within the sample.
  • Praziquantel Praziquantel: 5-8 mg/kg PO or SC as a single dose. This is repeated after 14 days.
  • Emodepside (1.98%) and praziquantel (7.94%) (Profender, Bayer): 1.12 mL/kg applied topically on thin skin, such as the neck of chelonians.
  • If the tortoise is healthy and is of the species that can hibernate, analysis of a pooled fecal sample is advised 4-8 weeks before winding down for hibernation Hibernation. Tortoises should not undergo hibernation with a heavy burden of internal parasites. They should also not be medicated with anthelmintics immediately before hibernation.


  • Coccidiosis Coccidiosis occurs in all species of reptiles.
  • Eimeria and Caryospora spp are reported in chelonians.
  • In heavy burdens, clinical signs include weight loss, diarrhea (sometimes hemorrhagic), anorexia, poor growth and death.
  • Diagnosis is by microscopy and visualization of the sporulated oocysts within the feces. Eimeria spp have 4 sporocysts and Caryospora spp have one sporocyst.
  • Life cycle is direct and reinfection is common if environmental factors are not addressed.
  • Transmission is via the oral-fecal route.
  • Potentiated sulfonamide (Sulfatrim, Virbac) which is licensed for Bearded dragons Bearded dragons: 15-20 mg/kg to be given either daily or on alternative days (after the second dose has been administered) for 7-14 days.
  • Trimethoprim/sulfadiazine: 15-30 mg/kg IM once daily for 7 days or 25 mg/kg PO once daily for 7 days.
  • In refractory cases, toltrazuril (Baycox) may be prescribed: 5-20 mg/kg PO daily for 3-5 days. 

Ciliates and flagellates

  • Ciliates and flagellates are commonly seen in herbivorous chelonians Flagellate/ciliate infection.
  • Often detected in fecal analysis, the ciliates Nycothersus spp and Balantidium spp, and flagellates are non-pathogenic commensals.
  • Trichomonads appear to be commonly reported in the literature:
    • Heavy burdens may be associated with immunosuppression and underlying diseases.
    • Clinical signs include weight loss, diarrhea and anorexia.
  • The pathogenic flagellate Hexamita parva may cause fatal renal disease Renal disease.
  • Diagnosis is by fecal flotation Fecal flotation: visualization of the ciliates and flagellates under microscopy of fresh fecal samples.
  • Hexamita parva may be identified within urine: definitive diagnosis of Hexamita parva requires detection of the parasite from a renal biopsy.
  • Metronidazole Metronidazole: 50-100 mg/kg PO as a one off dose; repeat 14 days later.


  • Entamoeba invadens is of clinical concern Amebiasis, it is more commonly seen in snakes but has been reported in chelonians, with giant tortoises appearing susceptible.
  • Aquatic chelonians are common reservoir hosts.
  • Clinical signs include anorexia, dehydration and diarrhea.
  • The liver and kidney may be affected via haematogenous spread.
  • Diagnosis is by visualization of the cysts and motile trophozoites under microscopy.
  • Metronidazole Metronidazole: 50-100 mg/kg PO as a one-off dose; repeat 14 days later.
  • Iodoquinol: 50 mg/kg PO once a day for 21 days, used as a treatment alone or in combination with metronidazole to stop cyst shedding.
  • Chloroquine: 50 mg/kg IM once a week for 3 doses; effective against amoebic trophozoites.


  • Chelonians are also affected by ectoparasites.
  • Ticks, leeches and Cuterebra larvae can be found in chelonians.
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Sample collection

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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.
  • Martinez-Silvestre A (2011) Massive Tachygonetria (Oxyuridae) infection in a Hermann’s tortoise (Testudo hermanni). Consult J (Special Edn), 409-412 pdf.
  • Machin R A (2015) Common gastrointestinal parasites in reptiles. In Pract 37 (9), 469-475 VetMedResource.
  • Mans C (2013) Clinical update on diagnosis and management of disorders of the digestive system of reptiles. J Exotic Pet Med 22 (2), 141-162 JExoticPetMed.
  • Brames H (2008) Efficacy and tolerability of Profender in reptiles: spot on treatment against nematodes. Exotic DVM 10 (3), 29-34 VetMedResource.
  • Giannetto S, Brianti E et al (2007) Efficacy of oxfendazole and fenbendazole against tortoise (Testudo hermanni) oxyurids. Parasitol Res 100 (5), 1069-1073 PubMed.
  • 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.
  • Innis C (1995) Per-cloaca worming of tortoises. Bull Assoc Rept Amphi Vet 5, 4.
  • Satorhelyi T & Sreter T (1993) Studies on internal parasites of tortoises. Parasit Hung 26, 51-55 VetMedResource.
  • 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.
  • Rivera S (2017) Chelonians. In: Exotic Animal Medicine for the Veterinary Technician. 3rd edn. Eds: Ballard B & Cheek R. Wiley-Blackwell. pp 183-196.
  • Klingenberg R (2012) Understanding Reptile Parasites. i5 Publishing.
  • Innis C (2008) Clinical Parasitology of the Chelonian. In: Proc NAVC, Orlando. pp 1783-1785.
  • Schneller P & Pantchev N (2008) Parasitology in Snakes, Lizards and Chelonians. Edition Chimaira. Frankfurt Am Main. pp 105-172.
  • 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.
  • Girling S (2004) Formulary. In: BSAVA Manual of Reptiles. 2nd edn. Eds: Girling S J & Raiti P. BSAVA, UK. pp 352-356.
  • Klingenberg R J (2000) Reptilian Parasite Testing. In: Laboratory Medicine: Avian and Exotic Pets. Ed: Fudge A M. W B Saunders, UK. pp 258-264.
  • Wright K M (1997) Common Medical Problems of Tortoises. In: Proc NAVC. pp 769-777.
  • Lane T J & Mader D R (1996) Parasitology. In: Reptile Medicine and Surgery. 2nd edn. Ed: Mader D R. Elsevier Saunders, USA. pp 186-203.
  • Frye F L (1991) Biomedical and Surgical Aspects of Captive Reptile Husbandry. 2nd edn. Ed: Frye F L. Kriegar Publishing.
  • 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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