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What are Protozoal Diseases?

There are many species of protozoa that can infest lizards, and just as many factors that can predispose a lizard for infection, as well as increase the numbers of protozoa in the host. The stress of captivity can severely affect the immune system, as can environmental temperatures, sanitation, age of the lizard, health condition of the lizard, and concurrent disease. Once established, protozoa can compete for food with the host, remove internal tissue and fluids, block blood vessels and the lymph system, and create swelling, tissue death and many other serious complications.

Protozoans are parasitic single-celled organisms that can infect and cause disease in lizards. While a small population can live in a lizard without any problems, a larger population, or specific species, can cause serious issues that can affect the gastrointestinal tract, and lead to weight loss, debilitation, and death. While meat eating lizards seem to be more susceptible, any lizard exposed to infected animals or contaminated soils, food, or objects can be affected. Lizards who show no signs of an infestation can be carriers, and can shed protozoan cysts which can infect healthy animals.

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Symptoms of Protozoal Diseases in Lizards

Symptoms can vary, depending on the type of protozoan infecting your lizard. While some lizards are asymptomatic, they can remain carriers. Signs that your lizard is infected with a protozoa include: 

  • Loss of appetite
  • Weight loss
  • Vomiting or regurgitation
  • Mucus or bloody feces
  • Diarrhea or soft, unformed feces
  • Feces containing undigested food particles
  • Dehydration
  • Weakness 
  • Depression 
  • Chronic debilitation
  • Star gazing 
  • Green discoloration of urine
  • Midbody or posterior swellings
  • Gastritis 
  • Intussusception of the intestines
  • Sudden death


There are many types of protozoa that can affect lizards. They include:

  • Amoebas, such as Entamoeba invadens 
  • Flagellates, such as Hexamita spp., Tritrichomonas, Trichomonas, and Giardia
  • Coccidial organisms, such as Klossiella, Isospora, and Eimeria 
  • Plasmodial (malarial) organisms
  • Cryptosporidium spp., the infection of which is called Cryptosporidiosis 
  • Ciliates, such as Balantidium spp. and Nyctotherus
  • Opalinida 

Causes of Protozoal Diseases in Lizards

The cause of protozoal disease is from the direct contact with the cyst form of protozoan species. This occurs by:

  • Ingestion of protozoan cysts, often from contaminated feces, soil, water, or objects
  • Copulation 
  • Ingestion of infected insects, mice, lizards, or other prey animals 
  • Contaminated cleaning tools
  • Humans handling infected animals before handling uninfected ones

Diagnosis of Protozoal Diseases in Lizards

A diagnosis is based on clinical signs, a history of possible infection, and the results of testing. For many species, tests of your lizard’s droppings can provide a positive identification. If you have a fresh sample of your lizard’s feces, bring it with you in a sealed Ziploc bag close to the time of your appointment, keeping it at room temperature. Tests can also be run on regurgitated food, vomit, or a cloacal wash. An endoscopic gastric biopsy can be used to gather stomach wash for testing as well. Multiple samples may be needed as some protozoan parasite levels can be too low to detect. Special stains may be used to differentiate between species. Cryptosporidium spp can also be detected through a palpation of a midbody swelling.

Your veterinarian may also perform blood work or other tests. Once a protozoan species can be identified, treatment can begin.

Treatment of Protozoal Diseases in Lizards

Antiprotozoal drugs are often prescribed to destroy protozoa, and inhibit their growth and reproduction, such as metronidazole, tetracycline, paromomycin, benzimidazole, or dimetridazole. Sulfa drugs can also be prescribed, such as sulfadimethoxine and sulfamethazine, though they can cause dehydration or kidney issues, and may need electrolyte fluid therapy. Medications are often prescribed for 1 to 4 weeks. Tests are often run again to monitor the progress of treatment.

In cases of a coccidian protozoa, a complete cure can be difficult and is only seen in 50% of cases. Often, this protozoa will not respond to treatment and can be fatal. There are no known treatments for cryptosporidiosis that are proven to work consistently. Often, supportive care can help to stabilize your lizard, though euthanasia is often considered for this type of infection.

Supportive care includes ensuring hydration of your lizard through fluid therapy, and using proper sanitation and hygiene techniques. Any infected lizards should be kept isolated from others in the population to prevent the spread of the protozoa. Cage mates or other reptiles that have come into contact with your lizard should be tested. Lizards that test negative and maintain their weight over 45 days are considered at a low risk for carrying the protozoan infection.

Recovery of Protozoal Diseases in Lizards

Recovery depends on the type of protozoa that has infected your lizard, as well as the severity of the infection. Some species of protozoa can be reduced or eliminated through proper medications and the installation of good hygiene and sanitation practices to prevent a reinfection. There are species that are more difficult to eliminate, and can end in a fatality. Your veterinarian will discuss your lizard’s recovery outlook dependent on his particular case.

In any case of a protozoan infestation, maintaining strict hygiene and sanitation practices is crucial, as protozoans are zoonotic, meaning they can infect other types of animals, including humans. 

Ensure the safety of your lizards by quarantining and testing any new animals before introducing them into your population, avoid overcrowding, maintain proper temperature and humidity in enclosures and cages, avoid running water through several enclosures, and maintain strict sanitation practices consistently.