This website shall serve the information and education of keepers of reptiles, especially corn snakes and leopard geckos, and their veterinarians. Direct linking to this page is allowed, the use of any contents of this page (text or pictures, also if altered) is forbidden. English is not the author's first language, so please excuse eventual jolty diction. Suggestions are welcome (see below).
This version is not always as complete and updated as the German version, my apologies.
Why this website?
Cryptosporidia cause great losses in lizard and snake collections. This disease causes a complex of problems and additionally a financial disaster for commercial breeders. Therefore lots of malinformation is circulating in the internet. With this site I want to publish some facts in order to reduce insecurity and to optimize the abatement of this disease. Education shall advance the handling of the disease, its diagnostics and its therapy, but by no means it shall tempt lay people (which includes everyone than reptile-experienced veterinarians) to try to diagnose or treat. Hence medications are mentioned, dosages though are not stated. For the animals' health's sake diagnostics and therapies should always be performed by a specialized veterinarian.
What are Cryptosporidia?
Cryptosporidia are single-celled parasites of the genus Cryptosporidium (the systematic classification (Cl.:Coccidia) is currently pending). As the sporocysts, in which the sporozoites in coccidia are usually found, are absent Tyzzer described this species 1910 (J Med Res 23: 487-509) as Cryptosporidium (cryptein (greek) = to hide / sporos (greek) = litter, semen).
At least 27 species have been described, affecting many species of animals. Host specifity is not clear, the most known species is Cryptosporidium parvum, which causes diesease in humans (now subdivided in C. hominis and C. parvum. The infection takes place via the consumption of contaminated drinking water and causes unappeasable diarrheas in immune-suppressed people (e.g. AIDS-patients) which will often end lethally. The danger of an affection in healthy people is minor.
The two species most relevant in reptiles are C. serpentis und C. saurophilum.
Cryptosporidia have already been described in reptiles in 1925 (Triffitt), thus it is not a "new" diesease, but its prevalence has occured within the last few years only.
The protozoa are hardly opposable, by medication as little as by the immune system. They are located within the cell membrane, neither intracellular nor extracellular.
The oocysts (the cryptosporidia-"eggs") sporulate directly which makes them infectious at once. Additionally cryptosporidia are able to form two different types of oocysts: thin-shelled which infect cells within the host and thick-shelled which are being excreted with the hosts feces in order to infect other hosts.
While C. saurophilum is mainly found in lizards, infections with C. serpentis are primarily diagnosed in snakes. Both species though can infect lizards, snakes and chelonians.
The parasite is found especially in leopard geckos and corn snakes. Infections in colour mutations, or collections including such animals, are standing out. The suspicion stands to reason that the main infectious source are commercial breeders, whose immune compromised "designer-geckos/snakes" are infected and spread the disease throughout the world via reptile shows and trade. More sturdy animals are shedding the infectious oocysts without coming down with clinical symptoms themselves. Therefore the source of the infection is hardly traceable. Stress (transport, collectivisation etc.) or a high infectious pressure (many individuals, suboptimal hygiene) can cause a strong reproduction of pathogens.
Contrary to what is often claimed by commercial breeders cryptosporidia are by no means "normal" in any animal.
Healthy animals are free of cryptosporidia.
How do cryptosporidia infect my animal?
Oral ingestion of infected food (crickets which have eaten reptile feces) or water, also licking on soil, rocks, feces etc. transports the oocysts into the host. Because of their tinyness the oocysts could theoretically also be transported through the air. The vertical infection (mother to offspring) is not possible, but eggs can be contaminated while being deposited and the hatchling can become infected when hatching. In most cases a collection is being infected when a new individual is being introduced without the proper quarantine and examinations. The transmission within the collection proceeds to other reptiles via the keeper (or instruments used), even if strict hygiene protocols are being followed.
What are the clinical signs of cryptosporidiosis in reptiles?
Cryptosporidia proliferate directly under surface of the endothelial cells of the intenstinal tract, the upper layer of the mucous membrane. Infectious oocysts, containing four sporozoites, are being excreted and can be incorporated by the same or another host. The endogenous autoinfection takes place, when the sporozoites are infesting the adjacent cells.
In lizards C. saurophilum causes the intestinal form of cryptosporidiosis, the damages emerge in the gut. The mucous membrane is being destroyed causing inflammations, dehydration, maldigestion and malabsorbtion. Often the animals keep their appetite but are still slimming.
Snakes infected with C. serpentis tend to be sick with the gastric form of cryptosporidiosis. The proliferation of the protozoans in the stomach mucosal lining cause an induration of the tissue, causing the loss of its functionality. Few days after the ingestion of prey the snake will vomit. In the end stage the alteration becomes apparent.
Although the symptoms described are typical for a cryptosporidiosis other possible causes of disease should be ruled out by clinical and fecal examination.
How can the infection be diagnosed?
For the gastric form in snakes an examination of a sample collected by a gastric lavage, performed by a veterinarian 1-3 days after feeding, is recommended. For the intestinal form in lizards and chelonians fresh feces can be examined. Among other characteristics the small size of only about 4-6 μm makes these protozoans hard to detect in a simple fecal examination.
The specimen (feces, regurgitated prey, gastric lavage sample) can now be stained (e.g. karbolfuchsine or ziehl-neelsen) after an eventual preparation (flotation for oocyst-enrichment) in order to make a direct microscopic detection. This examination is indispensable for secure diagnostics and should always be accompanied by an indirect verification. As Cryptosporidia present many different antigenes they offer several ways of indirect detection. These indirect methods are for example the cryptosporidia-cell wall-antigene-detection via immunofluorescence-test or a koproantigene detection (fecal or gastral samples) via cryptosporidia-specific ELISA (Enzyme Linked Immunosorbent Assay). Serologic ELISAs (blood samples) are reasonable three months after infection. Immunochromatographic rapid tests (as used in cattle medicine) are not sensitive for reptile-cryptosporidia (Biron 2007). If there is no diagnostic evidence despite pronounced symptomatics a tissue sample can be taken for histologic examination. Due to the size and constitution of the affected organs or animals this is usually only practicable in necropsies.
The direct detection via electrone-microscopy is generally not practicable due to its operating expense. Several institutions though are developing a PCR (Polymerase Chain Reaction), which will securely detect cryptosporidia-DNA and even make a species determination possible.
Unfortunately all methods of detection are limited and leave the possibility of erroneous positive or negative results. Since the oocysts respevtively the antigenes are not being excreted continously, several examinations are necessary, especially in subclincal cases. Also the presence of C. muris in prey (rats, mice etc.) can falsify the results.
How to proceed with infected or sick animals and is there a possible treatment?
Unfortunately there is still no optimal therapy yet. The most important procedure is the strict spatial separation of the animals. In order to decrease the infectious pressure infected animals are to be quarantined individually in cages which can be easily cleaned up every day. Bedding can be newspaper or kitchen paper, water bowls and setup (cardboard box) shall be exchanged daily. Reduction of stress is necessary in order to stabilize the immune system. Administering immune modulators (as Zylexis ®) will be supportive. Infusions and oral protein solutions (as Bioserin ®) will help prevent emaciation.
Possible secondary bacterial or parasitic infections should be treated specifically only after a diagnosis.
The abatement of cryptosporidia does not show satisfactory results until now. Partly success treating the gastric form with hyperimmune bovine colostrum, the foremilk of infected cows, has been reported (Graczyk et. al. 2000). This though is not commercially available. New preparations containing cryptosporidium-antibodies are being tested by the author at the moment, until now without success. Also unconventional medications are being tested by the author, results will be published. Other antiprotozoan medications like Metronidazole (and other Nitroimidazoles), Makrolid-Antibiotics like Azithromycine or Sulfonamides and Toltrazruile, which is effective against Coccidia do not show a sufficient effect. Nitazoxanide (Alinia ®) which is being used in human medicine or Halofuginone (Halocur ®) which is used in cattle medicine did lead to severe organic damage and therefore cannot be used in reptiles. More studies are being conducted, but until now it cannot be used clinically.
Solely the Aminoglykoside-antibiotic Paromomycin (Humatin ®), which is used to treat Leishmaniosis in humans, can lead to a decrease or even cessation of pathogen-excretion without harming the patient, as it is not being absorbed. In fact there has been success treating sick individuals which now appear healthy, but the future will show if they are "crypto-free" in the long run. Until now these animals have to be considered infected and especially infective, although crypto-tests are negative.
Only if there is no possibility of housing the infected animals without any danger for others, or if the animals already show symptoms and do not respond to treatment, euthanasia unfortunately is the "therapy" of choice, as the disease leads to a massive loss of life quality and death.
In other cases an attempt of therapy is to be aspired under avoidance of spreading the pathogens.
Under no circumstances (potentially) infected animals shall be brought into trade, to shows or be alienated in any way.
At this point it shall be pointed out that any attempt of therapy or any euthanasia must be performed by a specialized veterinarian. Elsewise this would be a violation of pharmaceutical law and animal welfare.
Which disinfectants are suited?
Cryptosporidia have a very high tenacity, a very high resistance against outside influences. Even after months the oocystes can still be infective. Regular disinfectants cannot destroy their hull. Therefore one needs to resort to special disinfectants (like ammonia oder p-chlor-m-cresole (e.g. parafectans ® oder Neopredisan ®), which are noxious and shall only be used according to exact (veterinary) instruction. Cage contents must be exchanged or can be sterilized at 200° C for two hours. Regular freezing does not harm the cryptosporidia.
How can the spreading of the disease be stopped?
The adherence to simple safety rules (quarantine, periodical fecal examinations inclusive special examinations for cryptosporidia-diagnostics, good hygiene etc.) is the premise for avoidance of carry-over. Also if the vendor appeals trustworthy, newly acquired animals should always be examined. The bulk of infected animals comes from commercial trade, not from private breeding. Infected animals, or animals which could have direct or indirect contact with those shall not be sold.
Where can samples be gained and examined?
The reptile specialized veterinarian can gain fecal and gastic lavage samples. Fresh feces can also be sent in. If not all prospects of examination are present in the practice the samples can be forwarded to a specialized laboratory.
If samples are sent in, it is to be made sure that it is an amount large enough, fresh and well packaged (leakproof in a non-absorbing vessel in a cusioned envelope plus Your contact data, exam request etc.) in order to preserve suitability for examination. Dried crumbs, scraped off a rock or some feces-coloured sand are not suitable for a secure examination.
Recommended literature for veterinarians:
Praktische Parasitologie bei Heimtieren, Beck & Pantchev 2006
Reptile Medicine and Surgery, Mader 2005
Eine einfache Nachweismethode für Kryptosporidien im Kot. Zbl. Vet. Med.B 29, 324-327, Heine, J. 1982
Steve Upton (Kansas State Univ.): Basic Biology of Cryptosporidium
List of more relevant publications and links: click here
The author is available for herpetological or veterinary meetings with the lecture "Cryptosporidia - the leopard gecko plague".
I thank my colleagues Dr. Udo Hetzel and Dr. Nikola Pantchev for brisk exchange of information.
Notes and commentareis are welcome to be sent to
Kornelis Biron, Tierarzt (DVM)
Last update: 07.10.2007