Reptilian Cryptosporidiosis

Cryptosporidium serpentis described from snakes (Levine, 1980) and C. varanii (syn. C. saurophilum) described from lizards (Pavlasek et al., 1995; Koudela and Modry, 1998 ) are the only valid species, although as many as five species of Cryptosporidium infecting reptiles have been suggested based on oocyst morphology (Upton, 1990) and molecular studies (Xiao et al., 2004). Cryptosporidium serpentis infections in snakes and C. varanii infections in lizards are acquired for a lifetime, and self-cure was not observed (Cranfield and Graczyk, 1995, 2000, 2006; Cranfield et al., 1999). Although C. serpentis has been described from snakes, this species is virulent for lizards, and C. varanii described from lizards is virulent for snakes (Koudela and Modry, 1998; Xiao et al., 2004).

Cryptosporidium serpentis preferentially infects the stomach, whereas C. varanii preferentially infects the intestine of snakes and lizards. Cryptosporidiumhas been reported in approximately 80 species of reptiles, including snakes, lizards, and tortoises (O’Donoghue, 1995; Fayer et al., 1997; Graczyk et al., 1998; Cranfield et al., 1999, 2000;
Xiao et al., 2004; Cranfield and Graczyk, 2006). Most reports described clinical and subclinical infections in captive reptiles, whereas only subclinical infections have been reported in wild reptiles (Upton et al.,1989; Graczyk et al., 1997). Cryptosporidiosis is a common and sometimes life-threatening disease of captive snakes, lizards, and tortoises (Cranfield et al., 1999; Cranfield and Graczyk, 2000, 2006; Brownstein
et al., 1977).

A. Clinical Signs and Pathology

There are two manifestations of Cryptosporidiuminfections in reptiles: subclinical (i.e., carrier state), and clinical (i.e., gastritis, enteritis, and gastroenteritis) (Cranfield and Graczyk, 1995, 2000, 2006). Healthy reptiles are able to intermittently pass oocysts for years, oscillating between periods of excreting high numbers of oocysts to periods that are oocyst negative by acid-fast staining techniques. The prevalence of subclinically infected shedders can be high in a reptile collection (Carmel and Groves, 1993; Cranfield and Graczyk, 1995, 2000, 2006). Subclinical infections can be difficult to diagnosis
because of the low oocyst output, sometimes far below the detection threshold of 3.75
x 104 oocysts/g (Cranfield and Graczyk, 2006; Graczyk et al., 1995, 1996), and intermittent patterns of oocyst voiding.

Clinical signs in snakes are associated with gastric hyperplasia of the mucus-secreting cells (Brownstein et al., 1977). Snakes often have foul-smelling diarrhea and midbody swelling with reduction in lumen diameter; they can live from a few days up to 2 years after the appearance of clinical signs
(Cranfield and Graczyk, 1995, 2000, 2006). Weight loss often occurs with persistent or periodical postprandial regurgitation 3 to 4 days after a meal. The gastric mucosa appears edematous with mucosal thickening and exaggerated longitudinal rugae that have copious amounts of mucus adhered to it. The surface may exhibit petechiae, enlarged rugae, excess mucous, and multiple foci of necrosis. Microscopy of gastric tissue reveals hyperplasia and hypertrophy of gastric glands, atrophy of granular cells, edema
of the submucosa and lamina propria, and inflammation of the gastric mucosa characterized by infiltration with lymphocytes and heterophils. Cryptosporidium
infections in lizards has been associated with acute enteritis and bacterial gastritis
(Dillehay et al., 1986; Frost et al., 1994; Terrel et al., 2003; Taylor et al., 1999). Clinical signs include weight loss, anorexia, lethargy, and diarrhea. Histological examination usually reveals hyperplasia and mononuclear inflammation of the small intestine.

B. Diagnosis of Cryptosporidium Infection in Reptiles

1. Barium
In snakes with postprandial regurgitation and midbody swelling, a barium study is useful to differentiate between gastric occlusion due to mucosal swelling and a nongastrointestinal mass (Cranfield and Graczyk, 1995, 2000, 2006).

2. Fecal Examination
Historically, oocysts have been identified in reptile fecal specimens by examination of direct fecal smears stained with acid-fast stain. Epitopes of C. serpentis oocyst wall antigens produce positive reactions with fluorescein-labeled monoclonal antibodies that are commercially available. The MERIFLUOR test is over 16 times more sensitive than acid-fast stain for detection of C. serpentis oocysts (Graczyk et al., 1995). However, even with the increased sensitivity of the immunofluorescent antibody (IFA), multiple negative fecal tests must be performed to raise the confidence level that a snake is truly negative
for Cryptosporidium. Oocysts of Cryptosporidium mouse genotype are frequently seen in captive reptiles, which can confound the diagnosis of cryptosporidiosis (Xiao et al., 2004).

3. Endoscopy
Endoscopy requires expensive equipment, and visual images of the gastric rugae and intestinal epithelium are difficult to interpret (Cranfield and Graczyk, 1995, 2000, 2006).

4. Gastric Lavage and Cloacal Swabs
Gastric lavage and cloacal swabbing can be performed on inappetant and nondefecating reptiles (Graczyk et al., 1996). Cloacal swab smears were demonstrated to be far less effective than gastric lavage smears. Because the pathogen resides in the stomach area, it is expected that in nondefecating reptiles higher concentrations of oocysts would be found in stomach aspirates than in cloacal swabs. Gastric lavage is performed by passing a tube into the stomach located at the midpoint between the head and the cloaca of a snake. Phosphate-buffered saline (equal to 2% of total body weight) is passed through the tube into the stomach and then aspirated with the snake held head down, retrieving approximately 50% of the administered fluid. The aspirate is centrifuged and a smear prepared from the pellet. Stomach aspirates contain little particulate matter and, therefore, acid-fast stain detection is nearly as sensitive as IFA staining (Graczyk et al., 1996). Additionally, it was noted that the gastric lavage test was more sensitive if performed within 3 days of eating (Graczyk et al., 1996). Because the metabolic rate of gastric mucosal tissue increases over 22 times after a meal, it is proposed that the
Cryptosporidium
reproductive cycle increases with the metabolic increase in the gastric mucosa. It may be beneficial to administer an appropriate baby food via a stomach tube meal to an inappetant reptile 3 days prior to the stomach lavage.

5. Regurgitated Material
Examination of smears of the parasite-rich mucus surrounding a regurgitated meal utilizing either the acid-fast or IFA stain can provide a definitive diagnosis (Cranfield and Graczyk, 1995, 2000, 2006).

6. Gastric Biopsies
This is a relatively safe procedure that can aid in the prognosis of a case when
Cryptosporidium developmental stages are found in the biopsy material. However, the nonuniform distribution of the pathogen on the gastric mucosa or intestinal epithelium makes a negative outcome difficult to interpret (Cranfield and Graczyk, 1995, 2000, 2006).

7. Serum Antibody Test
Serum antibody enzyme-linked immunosorbent assay (ELISA) utilizing C. serpentis
oocyst wall antigen has shown great sensitivity and specificity in surveys of reptile collections and in blind studies (Graczyk and Cranfield, 1997). The test diagnoses exposure to Cryptosporidium and can identify Cryptosporidium negative reptiles to establish pathogen-free colonies, and for selection for Cryptosporidium research.

8. Postmortem Examinations
Several stomach and intestinal (for C. varanii) tissue sections should be obtained for histological examination (Cranfield and Graczyk, 1995, 2000, 2006). On rare occasions,
Cryptosporidium positive reptiles diagnosed on fecal samples were found to be negative on postmortem examination when limited samples of gastric tissue were collected.

C. Treatment
Treatment regimes for reptiles have originated from the experiences of human and domestic animal treatment. The high morbidity and moderate mortality caused by
Cryptosporidium in ophidian collections is due to the lack of anticryptosporidial pharmaceuticals that can be safely and efficaciously used for prophylaxis or therapy (Cranfield and Graczyk, 1995, 2000, 2006). For reptiles, trimethoprim sulfa (30
mg/kg) once a day for 14 days and then 1 to 3 times weekly for several months, spiramycin 160 mg/kg for 10 days, and paromomycin at 100 mg/kg for 7 days and then twice a week for 3 months has been used (Graczyk et al., 1996). Halofuginone, paromomycin, and spiramycin reduced the number of voided oocysts, but did not eliminate infection as determined by histological sections. Furthermore, halofuginone
was severely hepatotoxic and nephrotoxic for snakes that were already physiologically debilitated by chronic Cryptosporidium infections. Trimethoprim-sulfamethoxazole and trimethoprim-sulfadiazine treatment resulted in oocyst-negative stools, but gastric biopsies of treated snakes revealed the pathogen in the mucosa (Cranfield and Graczyk, 1995; Graczyk et al., 1996). Therapy based on the protective passive immunity of hyperimmune bovine colostrum (raised against C. parvum in dairy cows immunized
during gestation) was efficacious in treating subclinical and clinical C. serpentis
infections in snakes and lizards (Graczyk et al., 1998, 1999, 2000). Six gastric colostrum treatments, delivered at 1% of the snake’s weight at weekly intervals histologically cleared C. serpentis in subclinical infections and regressed gastric histopathological changes. Supportive treatments, such as high temperatures, subcutaneous fluids, regular stomach tubing of highly digestible foods, and the elimination of any concurrent
disease problems, appear to act synergistically with treatment aimed at Cryptosporidium.

D. Prevention and Control
Cryptosporidium can be transmitted directly via the fecal-oral route or indirectly by contamination of food or water, e.g., utensils, feeding bottles, and cages (Cranfield and Graczyk, 1995, 2000, 2006). The oocysts, which are fully sporulated and infectious when excreted, are resistant to environmental stressors and to a wide range of commonly used disinfectants. Ammonia (5%) and formal saline (10%) were the most effective in altering oocysts’ infectivity after 18 h at > 4°C (Cranfield and Graczyk, 1995). Strict high-standard hygiene, good management, and isolation of infected animals are essential in prevention of spreading of Cryptosporidium within captive reptiles.

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Thanks for this, not been keeping reptiles as long as some and i was wondering what Crypto was.

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I was hoping to give some information here that is less commonly available, but quite important. I really think this is something people should read and be aware of. I'm not an expert but i'm happy to discuss it with people, and for people to supplement what is here with other information.

Andy

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it would be useful to have a list of papers like this on each of the common parasites and infections as a sticky

thanks for the information

Might be an idea to dumb it down for people. I found it a very interesting read. thanks.

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I Know what you mean, but I'm not sure dumbing it down is the best idea. But, I'll do my best to answer any questions people have about it.

Andy

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Oh, and If any one is interested I can give you the reference list for this paper.

Andy

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Good info. I am currently anxiously waiting for test results to come back hoping that my Dragons are not infected.

woo nice job! its a nightmare when i was looking up illnesses on google trying to find one that makes sence, and this it does

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Cheers mate.

I guess some will find it hard going, but its worth a read. We could maybe do with a section for illness, with some break downs. Not that I'm suggesting self diagnosis, just that a lot of less reliable information gets passed around, and some times its useful to know a few facts.

Andy

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