Exotis ISSN 2398-2985

Reptiles

Coccidiosis

Contributor(s): Vetstream Ltd, Mark Naguib

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Introduction

  • Cause: Eimeria spp, Isospora spp, Caryospora spp, Choleoeimeria spp, Sarcocystis spp and Cryptosporidium spp.
  • Signs: diarrhea, anorexia, weight loss, failure to gain weight.
  • Diagnosis: fecal flotation, direct smear.
  • Treatment: coccidia have a direct life cycle, and sulfonamides are the preferred treatment.
  • Prognosis: generally good.

Overview

  • Coccidia are intracellular protozoan parasites that usually have a direct lifecycle.
  • A number of coccidian parasites are found in reptiles but their pathogenicity is variable.
  • Pathogenicity is dependent on the species, host and the level of parasitism.
  • Isospora, Eimeria, Caryospora, Choleoeimeria, Sarcocystis and Cryptosporidium are most commonly seen.
  • Isospora amphiboluri is the most common species seen in clinical practice, particularly in the inland bearded dragon (Pogona vitticeps) and is usually non-pathogenic.
  • Damage to the intestinal mucosa leads to weight loss, dehydration, secondary infections, renal disease and death.
  • Intranuclear coccidiosis is a highly pathogenic emerging disease of chelonia.

Intranuclear coccidiosis

  • Intranuclear coccidiosis is an emerging disease of chelonians that affects a wide range of species.
  • The coccidian parasite has an intranuclear developmental stage, although details of its complete life cycle are not known.
  • The organism has yet to be properly identified but it is likely related to Eimeria arnyi.
  • Cells of multiple organs can be affected.
  • Signs: rhinosinusitis, oronasal fistulae, lethargy, rapid weight loss, open-mouth breathing and swollen vent. The degree and severity of clinical signs depend on chronicity and which organs are affected. There may be weight gain associated with fluid retention and ascites. Most animals presented with clinical disease succumb to the illness.
  • Diagnosis: intranuclear coccidiosis in the lungs has been reported in chelonia by biopsy, although a polymerase chain reaction (PCR) test has been developed. Renal or pancreatic biopsy yield the highest chance of positive samples.
  • Prognosis: post mortem diagnosis is based on the histopathologic finding of intranuclear developing stages in multiple organs or by PCR testing; antemortem samples (cloacal/choanal/conjunctival swabs) can be tested via PCR.
  • Treatment: remains unrewarding; however, there is anecdotal evidence that treatment of asymptomatic positive animals with toltrazuril may halt disease progression.
  • Prognosis: generally very guarded to poor. Morbidity and mortality is high, but some animals may recover and become carriers. Recrudescence has also been observed.

Pathogenesis

Etiology

  • Coccidiosis is directly transmitted via the fecal-oral route and is most commonly caused by protozoans of the genera Eimeria, Isospora and Caryospora.
  • The lifecycle of coccidia in lizards is similar to that seen in mammals:
    • Oocysts passed in the stool sporulate outside the body and are ingested by a suitable host.
    • Sporozoites are released to invade host epithelial cells and mature.
    • The epithelial cell ruptures and releases merozoites, which infect other cells and then can either multiply to infect yet other cells or form intracellular gametocytes; the latter eventually become infective oocysts, which are passed in the stool.
  • Sarcocystis are passed fully infective, but require a prey species as intermediate host which is then eaten by the final host.
  • Cryptosporidium are also passed fully infective.
  • Clinical disease results from cellular destruction and from secondary bacterial infection.
  • Weight loss and malabsorption are common in advanced cases.
  • Chronic dehydration from fluid loss can lead to renal failure.

Predisposing factors

General

  • Stress including overcrowding and recent movement.
  • Concurrent infections.
  • Poor hygiene.
  • Adenovirus infection.
  • Contaminated prey items.

Pathophysiology

  • Understanding the pathophysiology is important because infective oocysts are shed intermittently; thus, clinical disease can occur in the absence of a detectable infectious agent.

Timecourse

  • Variable.
  • Clinical signs can appear suddenly following stress.

Epidemiology

  • Is infectious and can be secondary to poor husbandry so clusters may be seen.

Diagnosis

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Treatment

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Prevention

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Cullion F T & Scullion M G (2009) Gastrointestinal protozoal diseases in reptiles. J Exotic Pet Med 18 (4), 266-278 ScienceDirect.
  • Garner M M et al (2006) Intranuclear coccidiosis in tortoises: nine cases. Vet Pathol 43 (3), 311-320 PubMed.
  • Greiner E C (2003) Coccidiosis in reptiles. Semin Avian Exotic Pet Med 12 (1), 49-56 ScienceDirect.

Other sources of information

  • Klaphake E, Gibbons P M, Sladky K K & Carpenter J W (2018) Reptiles. In: Exotic Animal Formulary. 5th edn. Ed: Carpenter J. Saunders Elsevier, USA. pp 81–166.
  • Cheek R & Crane M (2017) Snakes. In: Exotic Animal Medicine for the Veterinary Technician. 3rd edn. Eds: Ballard B & Cheek R. Wiley-Blackwell. pp 137-181.
  • Wilson B (2017) Lizards. In: Exotic Animal Medicine for the Veterinary Technician. 3rd edn. Eds: Ballard B & Cheek R. Wiley-Blackwell. pp 95-136.
  • Meredith A (2015) Ed BSAVA Small Animal Formulary: Part B - Exotic Pets. 9th edn. BSAVA, UK. pp 195.
  • Girling S J (2013) Common Reptile and Amphibian Diseases. In: Veterinary Nursing of Exotic Pets. 2nd edn. Wiley-Blackwell. pp 306.
  • Denver M C (2008) Reptile Protozoa. In: Zoo and Wild Animal Medicine. 6th edn. Saunders Elsevier, USA. pp 154-159.
  • Greiner E & Mader D R (2006) Parasitology. In: Reptile Medicine and Surgery. Ed: Mader D R. Saunders Elsevier, USA. pp 343-364.

Reproduced with permission from Bonnie Ballard & Ryan Cheek: Exotic Animal Medicine for the Veterinary Technician © 2017, and Simon J Girling: Veterinary Nursing of Exotic Pets © 2013, published by John Wiley & Sons.


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