Cryptosporidiosis in reptiles

Cryptosporidiosis has been reported in several reptile species. This disease appears to be common in wild and captive populations of reptiles, and transmission occurs via the fecal-oral route. Infected reptiles may not show symptoms, but oocysts (eggs) are occasionally shed. Clinical signs of Crypto infection include upset stomach and weight loss, along with abnormal enlargement of the mucous membrane layer of the stomach.

Diagnosis of cryptosporidiosis can be challenging. One diagnostic method is to identify oocysts within a stool sample using an acid-fast stain. A negative acid-fast stain indicates that the reptile was not shedding at the time of sampling and does not mean that the animal is Crypto-free. Standard practice is to test the animal three times before accepting it as disease-free. Endoscopy, including gastric lavage and biopsy, can also be used to identify this disease.

The most common species of Cryptosporidiosis found in reptiles are C. serpentis, C. muris and C. parvum. It has been suggested that the C. parvum occysts found (based on mice) probably came from rodents ingested by reptiles and from actual Crypto infections. This possibility of C. parvum infecting reptiles can be completely ruled out by specific biological and genetic tests.

In March 1999, the Saint Louis Zoo began a diagnostic euthanasia program after identifying chronic Cryptosporidium in snakes in its facility. To monitor the effectiveness of the control measures, samples were taken periodically from the snakes for a year. Immediately after the start of the control measure, 5 of 10 and 8 of 17 snakes tested positive for Crypto in May and June 1999, respectively. Subsequently, out of 45 snake samples taken at five different time periods, only 1 was positive for Cryptosporidiosis.

There are currently no effective control strategies against Cryptosporidium in reptiles. In a small-scale study, it was shown that snakes with clinical and subclinical Cryptosporidium can be treated (not cured) with hyperimmune bovine colostrum cultured against C. parvum. Strict hygiene and quarantine of infected and exposed animals are mandatory to control Cryptosporidiosis, but most choose to euthanize infected ones. The best method to prevent the spread of crypto is to euthanize infected reptiles.

Crypto-oocysts are neutralized only by exposure to moist heat at 113°F to 140°F for 5 to 9 minutes and disinfection with ammonia (5%) or formalin (10%) for 18 hours. Ineffective disinfectants include idophores (1-4%), cresylic acid (2.5% and 5%), sodium hypochlorite (3%), benzalkonium chloride (5% and 10%) and sodium hydroxide (0.02m). Everything that may have come into contact with an infected reptile should be thoroughly cleaned with an ammonia solution and allowed to dry for at least 3 days.