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This provides some facts and common myths about the parasite Cryptosporidium, aka “crypto”, in a comprehensive article targeted for the average lizard keeper, hobbyist, and breeder.


There are eleven strains of Cryptosporidium, which is a mutant form of Coccidia. These are single-celled protozoan parasites with a direct life cycle, which means that the microorganism can complete its life cycle (from egg to larvae to adult) within a single host animal’s body. Generally speaking, these parasites are ‘host specific’, meaning that certain strains of Cryptosporidium are adapted to cause disease only in specific hosts. The strains of crypto that infect reptiles are Cryptosporidium serpentis, and Cryptosporidium saurophilum. Unlike some myths claim, these strains are not zoonotic, or transmissible to humans or other mammals.

Most reptiles are considered susceptible to Cryptosporidiosis, especially snakes. Crocodilians are not known to have crypto. Rare cases of non-alimentary Cryptosporidium have been found in the kidneys and salivary glands of Iguanas. Cryptosporidium parvum is often observed when testing the feces of snakes, but this strain of crypto only causes infection in mammals, and most likely originates from mice feeders passing though the snake’s GI system.

Crypto affects snakes and lizards differently, and is much more difficult to diagnose in lizards because the symptoms are more elusive than in snakes. In lizards, the parasite invades the GI tract in the lining of the intestines creating inflammation and lesions that severely inhibit the absorption of nutrients. In snakes, it is the stomach wall that is affected which can cause fatal internal hemorrhaging.

Contagion and Transmission

Some experts claim that ALL lizards have Cryptosporidium, but this is completely unfounded and false. Most reptiles do carry sub-clinical, non-problematic coccidian microorganisms, but not crypto. Contrary to common myths, crypto is not easily transmitted by casual contact with skin and clothes. In its reproductive stage, when oocysts (spores/eggs) are being shed, Cryptosporidia infection is spread by contact via oral and fecal contamination. Reptiles that are infected with Cryptosporidia pass oocysts through their feces, and orally via water and food bowls.

When uninfected reptiles share water and food bowls with infected animals, they can ingest crypto oocysts. Likewise, if they come in contact with infected feces, or consume insect prey that has ingested infected feces, the parasite can be easily transmitted.

Crypto infected reptiles can also continually re-infect themselves by using their own contaminated water bowls and contact with their own feces, which creates large loads of this parasite to build up in their GI system very quickly. Fastidious disinfection is required to eradicate crypto infection, and will be discussed later in this article.

Clinical Symptoms

Many reptiles are asymptomatic (no symptoms) but are known to be carriers of Cryptosporidium. The carrier status of lizards is not completely known yet, but it is known that the parasite may remain in a dormant state until the animal is subject to severe stress and/or immuno-suppression, and then begins to multiply to a clinical state. Unfortunately, most of the clinical symptoms of crypto infection are similar to other parasitic and bacterial infections, so making a diagnosis purely by symptoms is ambiguous.

The progressive symptoms of Crypto in lizards are:

  • anorexia, loss of interest in food
  • regurgitation of food and undigested skin shed masses
  • change in consistency of feces, florid diarrhea, ‘cottage cheesy’ stools
  • weight loss, wasting away, thin tail
  • enlarged, darkened liver (hepatic lipidosis, or fatty liver)
  • lethargy
  • death


There are stages of the disease when it is sub-clinical and extremely difficult to detect. Until recently, the only 100% accurate method of diagnosis for crypto was post-mortem pathology of the stomach and intestines. In most cases, Cryptosporidium must be shedding, or in their reproductive stage, in order to be detected by conventional microscopic methods, as normal/routine fecal tests (floats and/or smears) are unreliable and produce too many false negatives.

Today, more sophisticated and precise test methods are available to accurately diagnose Cryptosporidium infection. Samples of feces, regurgitated stomach contents, endoscopic biopsies, and by-products of cloacal or stomach flushes may be used to detect Cryptosporidium.

Acid-Fast Stain (AFS) Test:

This common method employs the use of carbol-fuchsin, which is a mixture of phenol (carbolic acid) and basic fuchsin ( a biological purplish-red pigment), because it has a natural attraction to the mycolic acids found in cell walls. This compound stains the walls of the Cryptosporidium oocysts, creating a bright red contrast visible on laboratory glass slides under 100X microscopic power. This test may need to be repeated several times in order to make a positive diagnosis, as the parasite is not always shedding (in its reproductive state) in order to be visibly observed.

Merifluor Immunofluorescent Assay (IFA) Test:

This test is 16X more sensitive than AFS method. This method uses the blood, saliva, or other bodily fluids from an animal that is then evaluated by a laboratory. Certain chemical reagents are used which cause the targeted antibody or antigen, (any substance that causes your immune system to produce antibodies against it) to link to an enzyme, which are complex proteins that cause a specific chemical change in other substances, without being changed themselves. If the target substance is present in the sample, the test solution turns a different color when observed through fluorescence.

Enzyme-linked immunosorbent Assay (ELISA) Test:

Similar to the IFA test, this procedure uses components of the immune system and chemicals to detect immune responses in the body (for example, to infectious microbes). The ELISA test involves an enzyme (a protein that catalyzes a biochemical reaction), and an antibody or antigen (immunologic molecules). The ELISA test is generally considered to be the most accurate test for diagnosing Cyrptospridium infection, but is also more elaborate and therefore more expensive to perform.


There is currently no medication or treatment available that will eliminate Cryptospoidia in reptiles, although there are promising treatments that seem to prevent the parasite from multiplying to levels where the infection is clinical. Current treatments appear to be more effective in snakes, and less so in lizards and tortoises. Many reptiles have maintained their health and have prolonged lives as a result of recent and ongoing treatment studies, but are still considered to be infected and can transmit the disease to other reptiles.

Since there is no ‘cure’ for crypto in reptiles at this time, the inevitable suffering and death of an infected lizard can be expected. Humane euthanasia is often the best course of action.

Some of the medications that are being tested and used are:

Bactrim/Septra/Albon (trimethoprim sulfa): A sulfa-based, broad spectrum antibiotic with excellent activity against most gram-negative organisms. This treatment has not proven to be effective in the treatment of Cryptosporidiosis in cold-blooded animals, but is very useful in treating Coccidiosis.

Halofuginone: An anti-coccidian agent which is an alkaloid originally isolated from the plant Dichroa febrifuga. This drug is similar to chemotherapy, which acts on rapidly multiplying cells. It does have a narrow margin of safety as it can actually weaken the immune system, which is a critical factor in keeping crypto suppressed.

Spiramycin: A macrolide antimicrobial agent (antibiotic) with activity against gram-positive and gram-negative organisms, including protozoans and many strains of bacteria. Since this medication also kills gram-positive bacteria which are essential for the digestive system to function properly, it can have detrimental effects by keeping the ‘good’ gut flora out of balance.

Paromomycin: A carbohydrate based drug that fights intestinal infections such as cryptosporidiosis and amoeba infection, or amoebiasis, by inhibiting protein synthesis within the organism. This treatment has proven more effective of Crytosporidia parvum, the type of crypto that affects mammals, but has limited effectiveness with cold-blooded animals.

Baycox (toltrazuril): A drug formulated specifically for the treatment of coccidian infections in farm animals. It interferes with the division of the nucleus and with the activity of the mitochondria, which is responsible for the respiratory metabolism of Coccidia. Since it was formulated for mammals, it also has limited effectiveness on reptiles.

Alinia (nitazoxanide): A drug formulated for humans used to treat diarrhea caused by the parasites Cryptosporidium parvum and Giardia lambia. This drug is currently being tested for treatment of Crypto in reptiles, but no definitive therapeutic results have been observed other than symptomatic relief.

Hyperimmune Bovine Colostrum (HBC): This treatment utilizes colostrum, a natural substance secreted by the mammary glands of cows, which provides passive immunity against Cryptosporidia parvum in mammals. Although HBC does not eliminate crypto in all reptiles, there is promising research being conducted* that may prove a cross-reactivity of the antibodies to that of Cryptosporidia serpentis.

-Studies performed by Drs. T. K. Graczyk, M. R. Cranfield, P. Helmer, R. Fayer, and E. F. Bostwick using Hyperimmune Bovine Colostrum have shown to eliminate Cryptosporidium in infected subject monitor lizards.

== Disinfection == Cryptosporidium are remarkably resistant to many common disinfectants because their cell walls are impermeable to chemicals and drugs. Crypto oocysts can remain viable up to 18 months in moderately cool, damp or wet environments, so complete disinfection is mandatory to prevent cross-contamination and perpetuating the infection.

-Ammonium compounds or straight household ammonia is most effective


The only success in eradicating Cryptospridium infection is through prevention. Isolation of infected and new animals, fastidious husbandry and cleanliness, reducing crowding and stress, and maintaining all animals in optimal health so that their immune systems are strong enough to fight off infection will be protocol.

As harsh as it seems, ANY reptile that has been positively diagnosed with Cryptosporidium should be humanely euthanized, and all cages and cage items discarded to protect any other reptiles in collections and colonies from being infected.

The following are guidelines in preventing crypto in reptile collections:

Quarantine ALL newly acquired reptiles, regardless of their origin, for at least 90 days. Practice fastidious husbandry and cleanliness during the quarantine period, and at all times.

  • Quarantine any reptile that exhibits ANY symptoms of disease or sickness, and seek veterinary care immediately! DO NOT try to diagnose problems yourself, and follow prescribed treatment(s) as ordered.
  • Acquire reptiles only from reliable sources. Avoid buying reptiles from large chain pet stores, and ‘reptile mills’ or suppliers that deal in huge, volume sales. These reptiles are only inventory items.
  • Obtain fecal samples for veterinary examination for every newly acquired reptile. Most reptile diseases and parasites are completely curable if diagnosed and treated expeditiously.
  • Never interchange or recycle food items between reptiles or their enclosures.
  • Never interchange water bowls, cage furniture, décor, or any enclosures between animals or habitats without complete prior disinfection.
  • Educate yourself on Cryptosporidium. The internet and/or your veterinarian are GREAT places to learn! With reptiles becoming more mainstream as pets, and more veterinarians being trained and specializing in reptiles, knowledge is the best weapon in the fight against Cryptosporidium, and other reptile parasites and diseases.

Works Cited

McGuiness, Marcia. Golden Gate Geckos. <Golden Gate Geckos>. custom essay