Reptile Protozoa

Chapter 19 Reptile Protozoa

Many species of protozoa are found in reptiles. Some may be commensal or nonpathogenic organisms, and others are pathogens. The two most clinically important diseases are cryptosporidiosis and amebiasis. Each of these parasites may infect a wide range of reptilian species and are easily transmitted because of direct life cycles.


Clinical Signs

Lizards and chelonians often exhibit poor growth or appetite, weight loss, or other, nonspecific findings, as well as postprandial regurgitation and passing of undigested food items.10,17,27 Snakes may be subclinically infected for years but capable of shedding the organism intermittently. Clinical signs of cryptosporidiosis in snakes may include anorexia, lethargy, intermittent or chronic regurgitation of undigested prey several days after feeding, chronic weight loss, and firm midbody swelling caused by gastric hyperplasia.3 Enteritis with severe inflammatory infiltrates without clinical or histologic signs of gastritis has been seen in wild-caught, rough green snakes (Opheodrys aestivus) and a garter snake (Thamnophis sirtalis). Sudden death was the presenting sign in these snakes.2 Three iguanas (Iguana iguana) presented with aural-pharyngeal polyps.28


Diagnosis may be challenging because oocysts are shed intermittently.

Necropsy and Histopathology

The pathologic changes seen grossly have been covered extensively in the literature and include increase in the diameter of the stomach, edematous rugae, thickening of the gastric mucosa, decreased lumen size, mucosal petechiae, and focal necrosis in predominantly gastric cases and mild to severe enteritis in other cases.2,3 Histologically, in infected animals, the organisms are seen on the brush border of the epithelial cells. There may be little damage to the architecture in subclinical cases, or substantial changes may occur, including loss of the brush border, hyperplasia and hypertrophy of gastric glands, proliferation of gastric mucous cells, edema and inflammation of the submucosa and lamina propria, reduced luminal diameter, and inflammation of the mucosal layer.3

In reptiles with intestinal infection, few gastric lesions may be seen. A marked infiltrative enteritis is usually present, with abundant parasites in the enterocytes.2,17,27

Prevention and Management

The cysts are extremely hardy and resistant to standard disinfection procedures, including sodium hypochlorite (bleach) and povidone-iodine. Heat above 60°C, thorough desiccation, or freezing may be used for appropriate nonorganic materials. Ammonia and 10% formalin were effective after 18 hours of contact.4 At the Maryland Zoo in Baltimore, during the years of Cryptosporidium research, ammonia foot baths were used at the door of each reptile quarantine room; ammonia was used for disinfection of tools and equipment after removal of organic matter; separate tools were used for each room in quarantine; and the keepers were knowledgeable and well trained regarding prevention of transmission of Cryptosporidium organisms. Despite this, transmission occurred from one group of snakes to another snake housed in a different room.2

The safest way to eliminate cryptosporidiosis from a collection is through strict quarantine protocols with rigorous testing procedures and elimination of infected individuals. Reptiles with subclinical infections may appear healthy but serve as a source of infection for other reptiles for many years. Reptiles should not be euthanized based on the presence of Cryptosporidium in fecal or gastric samples without confirmation of actual disease in the stomach or intestine by biopsy and histopathology. It is difficult to justify the euthanasia of reptiles testing positive for cryptosporidiosis in quarantine unless the entire current reptile collection has previously been tested and found negative.

Endangered reptiles with cryptosporidiosis that are not considered candidates for euthanasia, even if infected, should be kept strictly isolated from noninfected reptiles. Periodic testing and treatment when shedding may help prolong the quality of life and breeding potential of these endangered reptiles and may reduce transmission to the rest of the collection. There is no evidence of vertical transmission; eggs or offspring produced and removed from the adult environment immediately should have a reduced chance of infection.

Oct 1, 2016 | Posted by in EXOTIC, WILD, ZOO | Comments Off on Reptile Protozoa
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