Your Healthy Herp: What is Crypto?
By Aimee Kenoyer, PNWHS member
*Disclaimer: I am not a veterinarian and can only share information I have found. PNHS is not liable for any action taken based on the contents of this article. It is up to the individual to do their own research, and I strongly encourage all keepers to seek out trusted information sources and to rely on the advice of their veterinarian. If you suspect your animal is ill, please take it to a licensed veterinarian.
Cryptosporidium serpentis, or Crypto, is a relatively common disease that affects many types of reptiles and can be passed from species to species in a given collection. Periodically this disease surfaces in the greater area, and often the eventual result of the illness is death of the animal. This article is not meant to make everyone paranoid, but to offer information and allow us to make informed decisions that can protect our collections, and those of other keepers in our community. Aside from lack of information, in my opinion the biggest problem facing herp keepers in regards to the health of their animals is misinformation. In spite of the prevalence of Crypto in the reptile community, little is known by the average keeper about transmission, the course of the disease, treatment, and prevention. In order to learn more about Crypto, I went to the internet for some basic information. Once I had a general idea of what Crypto is, I consulted one of our veterinarians (Dr. Johnson-Delaney) and also gathered information from another who had consulted Dr. Cannon. I went to PubMed, compilation of peer-reviewed articles, to pull journal papers regarding current research about Crypto in reptiles. I also contacted Dr. Elliot Jacobson, the premier reptile researcher in the United States, to ask if he could give me some concrete, reliable information about Crypto. He generously sent me information from a roundtable conference of veterinarians and pathologists published in 2007 that included Dr. Garner, a pathologist affiliated with Northwest ZooPath. Specific resources are listed at the end of this article, but I’ll summarize what I found.Cryptosporidium has several species that can cause illness (called “cryptosporidiosis”) in animals, from reptiles to birds, to fish and mammals. It is a small protozoan parasite, commonly seen as oocysts, that infects primarily the intestinal tract, but has in some cases been seen in other organs upon necropsy (kidney, salivary gland). Cryptosporidium serpentis has not been found to infect amphibians, birds, mammals, or other types of animals aside from reptiles. A study was done several years ago wherein scientists exposed mice to C. serpentis, but they were unable to pass infection. This means that we are very unlikely to be able to catch Crypto from our reptiles, or to have it passed to other mammals in our household. However, the same Crypto that infects a snake can also infect a lizard or tortoise in the same collection. It is unclear whether aquatic turtles or crocodilians can be infected with Crypto, but representatives of most other types of reptile have been found to carry Crypto and Dr. Garner thinks “...all reptiles should be considered to be susceptible to cryptosporidiosis”. Research seems to show that Leopard Geckos and albino Pitouphis (Bull, Pine, and Gopher Snakes) are particularly susceptible to Crypto.
Crypto is passed from animal to animal by several routes: horizontal transmission, from one animal to another, usually via the fecal-oral route. This means a healthy animal will be exposed to fecal material from an ill animal and then become infected. Fecal material can be spread by flies, direct contact, your hands when handling your reptiles or cleaning enclosures, recycled prey items, and potentially as dust in the air. Crypto can also be passed by vertical transmission (from parents to offspring), probably as a result of fecal contamination on the egg or offspring as they pass through the cloaca.
Once an animal has been infected, there are several possible outcomes. One possibility is nothing; the oocysts will imbed into the intestinal epithelium and sit there throughout the life of the reptile. In some cases reptiles can be asymptomatic carriers, a state in which they don’t show signs of illness but can pass oocysts to other animals in their fecal matter. Sometimes an animal can carry the oocysts for long periods of time, then the oocysts will begin to reproduce and cause an active infection. Sometimes the infection is self-limiting, meaning that the animal will be ill and will shed oocysts for some time and then recover, going back to a carrier state once the immune system gets the infection under control. Sometimes the infection will eventually result in death. For example, a fatal case in Leos usually manifests like this: over a course of weeks to months the gecko will ‘waste away’, lose the characteristic fat tail, lose interest in food and eventually starve to death. An animal in a carrier state, even upon necropsy, will often show no gross (visible to the naked eye) evidence of infection and it must be found by microscopic examination of stained tissue sections or sometimes by other types of tests (such as ELISA). Animals with “clinical disease”, those with outward symptoms, typically have swollen stomachs and often the GI tract has swollen tissues, lesions, damaged tissue, and evidence of infection upon gross examination. Diagnosis of an animal at necropsy is relatively easy if the correct tests are performed, but diagnosis of an animal in a carrier-state can be tricky. The oocysts are not always shed in the feces, and false-negative results are common. Some veterinarians feel that a ‘wash’ of the GI tract will cause shedding of the oocysts in carrier animals, and indeed this increases your chances of an accurate test. Also, sequential fecal exams over time can be useful. However, there is no way to ever really be sure that your healthy-appearing reptile is crypto-free because of the way that the oocysts imbed into the stomach or intestinal tissues.So this is how Crypto looks in a reptile and how it can be diagnosed; how can it be treated? Well, unfortunately there’s not much out there for therapy. There are some treatments that show some promise: hyperimmune bovine colostrum, flushed through the GI tract, seems to be the most effective to date; this works by increasing the reptile’s immune response to the Crypto. There are drugs such as Halofuginone, Spiramycin, Paromomycin, Baycox, and Alinia; most of these will knock down the number of oocyts or treat the symptoms, but will not eradicate the infection completely and in some cases can cause as much harm as good (for example, Spiramycin is an antibiotic that also kills off gut flora, the normal bacteria in the reptile’s GI tract that can help keep numbers of oocysts down).
All right, so now we know what Crypto is, how it affects a reptile, and as much as is known about treatment options. Based on the poor prognosis of an animal with a clinical case of Crypto, how can we get rid of it? If we find it in one animal in our collection, how can we be certain the others won’t become infected as well? Crypto is a tough organism, and can live for months in usual environmental conditions. Drs. Cranfield and Craczyk, from the Baltimore Zoo and Johns Hopkins, say that “Most of the commercial disinfectants used according to the manufacturer’s instructions are ineffective against cryptosporidium oocysts.” The recommendations by the panel of experts who convened for the roundtable are ammonia, heat (150OF+), and dryness. Basically, to be pretty sure you’ve killed any oocysts present, use undiluted ammonia and let it sit for some time. Bake the item if possible. Leave it outside in the sun (UV can help) and make sure it’s completely, thoroughly dry. Dr. Raphael, from the Bronx Zoo, recommends sealing the item in big plastic bag after dousing with ammonia and leaving for at least 48 hours to let the fumes kill the oocysts. (*please use caution and work in a well-ventilated area when using undiluted ammonia, as fumes can be harmful to you and your pets). Other sources recommended the use of 10% Bleach for extended time periods, or quaternary ammonium compounds such as Roccal, diluted to the manufacturer’s specifications, also used for extended time periods.
So this is a little scary to the average herp-keeper. How many animals really have Crypto? How worried should we be about our own collections? Dr. Raphael says that about 20% of new snakes coming in to the zoo have Crypto and are usually asymptomatic carriers. Percentages of infection in Leopard Geckos are estimated to be quite a bit higher, from 30%-80% depending on the source. Dr. Johnson-Delaney is of the opinion that most reptiles probably carry Crypto, and that stress brought about by changes in husbandry or other factors can trigger active infection. She recommends a little healthy caution, but no fear or paranoia if your husbandry practices are good. Most sources indicated that casual contact with clothing was highly unlikely to pass the organism, so it’s not necessary to be frightened of outreaches or reptile shows. All sources consulted recommended quarantine of new animals and strict hygiene practices, especially when cleaning cages or dealing directly with fecal matter. Crypto does not have to be a death-sentence for a reptile unless compounded by other factors. Common sense, appropriate husbandry, a few basic precautions, and adequate disinfection practices will go a long way to protecting your collection and keeping your herps healthy.
Cryptosporidiosis. 2007 roundtable. Cranfield, MR; Craczyk, T; Wright, K; Frye, FL; Raphael, B; and Garner,
M. Moderated by R. Nathan, DVM.