Coccidiosis
Basic Information 
Definition
Coccidia are microscopic, spore-forming, single-celled parasites belonging to the Apicomplexan suborder Eimerorina.
Synonyms
Acroeimeria, Besnoitia, Caryospora, Choleoeimeria, Eimeria, Goussia, intranuclear coccidiosis, Isospora, Klossiella, Pythonella, Sarcocystis, Schellackia
Epidemiology
Species, Age, Sex
• Coccidiosis is seen in all species of reptiles that have been significantly investigated.
• With intestinal Coccidia spp., young animals tend to have the heaviest infestations and show the most significant clinical signs, although older immunologically naïve animals are also at risk.
• No age predilection is apparent for disease seen with extraintestinal coccidia.
• No sex predilection has been noted for any reptile coccidiosis.
Contagion and Zoonosis
• Coccidial oocysts generally are very stable in the environment.
• Fecal-oral transmission is the most common route of infection for coccidia with direct life cycles.
• For coccidia with indirect life cycles, definitive hosts are typically infected by ingesting intermediate hosts, and intermediate hosts are typically infected by fecal-oral transmission from definitive host feces.
• In some Sarcocystis spp., the same lizard species may alternate as definitive and intermediate hosts; this is known as a dihomoxenous life cycle.
• Zoonotic infection with coccidia of reptiles has not been documented.
Geography and Seasonality
The impact of geographic and seasonal factors on coccidiosis in reptiles is not well understood.
Clinical Presentation
History, Chief Complaint
• History associated with coccidiosis varies according to species of coccidia and host.
• Often, no clinical concerns are present, and coccidia are detected on a routine fecal examination.
• Clinical concerns presented by owners may include poor growth, weight loss, diarrhea, sudden death, rhinitis, anorexia, depression, and reluctance to move.
Etiology and Pathophysiology
• Three families of eimeriorinid coccidia are found in reptiles: Cryptosporidae, which is discussed in a separate section; Eimeriidae, of which the genera Caryospora, Eimeria, and Isospora have been described in reptiles; and Sarcocystidae, of which the genera Besnoitia and Sarcocystis have been described in reptiles.
• Most organisms are intracytoplasmic in host cells.
• Tissue cysts consistent with Besnoitia have been seen in the kidneys of basilisks (Basilicus basilicus); mesentery, intestine, liver, and spleen of ameiva (Ameiva ameiva); and heart of wall lizards (Lacerta dugesii).
• Known reptile Caryospora with indirect life cycles use snakes (viperids and North American ratsnakes) as definitive hosts, and form tissue cysts in mammals.
• Caryospora chelonae, which has a direct life cycle, is a significant pathogen in green turtles (Chelonia mydas), causing primarily intestinal lesions, although lesions may also be present in kidney, thyroid, and brain.
• Choleoeimeria hirbayah is a significant pathogen of veiled chameleons (Chamaeleo calyptratus).
• Eimeria spp. are the most commonly described coccidian parasites of reptiles.
The number of sporocysts/sporocytes has been used traditionally to classify coccidia as Eimeria, but the advent of sequence data has shown that this is not a reliably phylogenetically informative trait.
Eimeria have direct life cycles and usually are found in the intestinal epithelium.
• Intranuclear coccidiosis: Intranuclear coccidiosis is a significant disease of tortoises, causing high mortality:
Organisms are found in cell nuclei of numerous organs, including GI tract, liver, kidney, and spleen.
In Sulawesi tortoises, this organism has been associated with erosive rhinitis. The life cycle of this organism is not known.
Intranuclear coccidia have been seen in several lizard species, and these lizard coccidia have been called Isospora spp. based on sporulation, although no sequence data exist for these organisms.
• Isospora jaracimrmani can be a significant pathogen in veiled chameleons (Chamaeleo calyptratus), and I. amphiboluri can be a significant pathogen in bearded dragons (Pogona vitticeps).
• Klossiella boae has been reported from the kidneys of a Boa constrictor.
• Sarcocystis spp.: Sarcocystis spp. have indirect life cycles, forming tissue cysts in intermediate hosts, which then are ingested by carnivorous definitive hosts, where sporogony occurs:
Numerous species have been identified in reptiles.
Squamates are common definitive hosts, especially snakes.
Significant enteric disease has been associated with Sarcocystis in a bull snake (Pituophis melanoleucus sayi) definitive host.
Sarcocystis spp. can cause significant disease in mammalian and avian intermediate hosts; this may also prove to be the case in reptile intermediate hosts.
• Schellackia spp.: Schellackia spp. undergo schizogeny and sporogony in the gut of lizards.
Diagnosis 
Differential Diagnosis
• Differential diagnoses for weight loss and diarrhea include poor husbandry and numerous causes of enteritis and metabolic disease.
• Differential diagnoses for depression and systemic disease include malnutrition; bacterial, fungal, viral, and other parasitic diseases; numerous metabolic diseases; and neoplasia.
Initial Database
A thorough history, physical examination findings, complete blood count, plasma chemistry, radiographs, and fecal examination form the basic database.
Advanced or Confirmatory Testing
• Because the clinical significance and approach vary greatly depending on coccidian species, identification of coccidia is essential.
• For enteric forms, fecal flotation may identify the presence of oocysts. Nonenteric forms require samples of infected tissue. Schellackia spp. may be seen on blood smears.
• Nested polymerase chain reaction (PCR) with product sequence analysis is available for all coccidia from the University of Florida. Samples containing the organism are the samples of choice.
For postmortem samples, collecting two sets of tissues—submitting one in formalin for histopathologic examination to identify infested tissues, and freezing back a second set with no formalin for PCR identification—is advised.
• Images of the different coccidia usually are not reliable for differentiation.
Treatment 
Therapeutic Goals
• The goal of treatment varies according to species of coccidia and host.
• For species that are significantly pathogenic, eradication of coccidia is the goal when feasible.
• When not verifiable ante mortem, as in species found in viscera, the goal may be alleviation of disease.
• For species that are not significantly pathogenic, treatment may not be indicated, especially in nonbreeding situations or where parasites have indirect life cycles.
Acute General Treatment
• Treatment varies according to species of coccidia and host.
• For coccidia with direct life cycles, very fastidious hygiene practices are necessary to prevent reinfestation. This is frequently underemphasized, and without this, pharmacologic treatment will fail.
• For debilitated animals, supportive care such as fluid therapy and treatment of secondary infection may be indicated.
• For coccidia with indirect life cycles, access to intermediate hosts needs to be removed.
• Anticoccidials can be used. However, data are lacking on safety, pharmacokinetics, and efficacy of anticoccidials in reptiles; all doses to date are empirical. Some empirical drugs and doses that may be used include the following:
Ponazuril (Marquis) 5-20 mg/kg PO q 24 h × 28 d
The above dose is based on studies from mammals.
An empirical dose of 30 mg/kg (2 doses 48 hours apart) has been used to treat bearded dragons with coccidiosis, and oocysts were not seen following treatment.
Toltrazuril (Baycox) 5-20 mg/kg PO q 24 h × 28 d
Comment from the editor: Alternatively, 5-20 mg/kg PO q 24 h × 3-5 d has also produced positive results.
Nitazoxanide (Navigator) 25 mg/kg PO q 24 h × 5 d, then 50 mg/kg PO q 24 h × 23 d
Amprolium hydrochloride 10 mg/kg PO q 24 h × 7-12 d
Sulfadimethoxine 90 mg/kg PO, then 45 mg/kg PO × 7-10 d
Trimethoprim/sulfamethoxazole 30 mg/kg PO q 24 h × 2 d, then q 48 h × 26 d
Godfrey, SS, et al. Transmission mode and distribution of parasites among groups of the social lizard Egernia stokesii. Parasitol Res. 2006; 99:223–230.
Gordon, AN, et al. Epizootic mortality of free-living green turtles, Chelonia mydas, due to coccidiosis. J Wildl Dis. 1993; 29:490–494.
Innis, CJ, et al. Antemortem diagnosis and characterization of nasal intranuclear coccidiosis in tortoises. J Vet Diagn Invest. 2007; 19:660–667.
Matuschka, FR. Reptiles as intermediate and/or final hosts of Sarcosporidia. Parasitol Res. 1987; 73:22–32.