Cryptosporidiosis in leopard geckos — caused by Cryptosporidium varanii (formerly C. saurophilum) — produces chronic, progressive weight loss and regurgitation despite normal or increased eating. Known as "Crypto," it is incurable in most cases and spreads easily between geckos. A thin, emaciated gecko that keeps eating is the classic presentation.
Last reviewed: June 2026
What Is Cryptosporidiosis in Leopard Geckos?
Cryptosporidium varanii infects the gastrointestinal epithelium of leopard geckos, destroying intestinal villi and preventing nutrient absorption. Despite this, affected geckos continue eating but absorb little, leading to progressive weight loss.
Crypto spreads via the fecal-oral route; oocysts are immediately infectious and resist standard disinfectants — bleach at typical concentrations does not reliably kill Cryptosporidium oocysts.
As described in Mader's Reptile and Amphibian Medicine and Surgery, C. varanii should be considered in any leopard gecko with chronic progressive weight loss and regurgitation, particularly if the gecko is from a collection or was recently purchased from a pet store or breeder.
Signs of Cryptosporidiosis in Leopard Geckos
The classic triad:
- Chronic weight loss — the most consistent sign; the gecko loses tail fat reserves first (the tail becomes thin and rope-like), followed by overall body wasting
- Regurgitation — partially digested or undigested food regurgitated hours after eating; this occurs because the damaged intestine cannot process food normally
- Normal or increased appetite — the gecko actively hunts and eats, which makes the weight loss more alarming and distinguishes Crypto from many other diseases
Additional signs:
- Progressive muscle wasting — the hip bones and spine become visible as fat is consumed
- Intermittent soft or abnormal stools, or visible undigested food in droppings
- Lethargy in advanced disease
- Bloated or distended abdomen in some cases (due to intestinal inflammation)
Tail assessment: The tail normally serves as a fat reserve in leopard geckos. A healthy tail is plump and carrot-shaped. A "stick tail" — thin, pointed, wrinkled — is a red flag for chronic malnutrition or systemic disease, with Crypto being among the most common causes in adults.
Diagnosis and Management
Diagnosis:
- Fecal PCR: The most sensitive available test; detects Cryptosporidium DNA in fresh or refrigerated feces. A single negative result does not rule out infection (intermittent shedding); 3 samples collected on different days are recommended
- Acid-fast staining of feces: Can identify oocysts; less sensitive than PCR
- Endoscopy/biopsy: Definitive but invasive; reveals characteristic intracellular organisms in intestinal epithelium
Treatment — guarded prognosis: Currently, there is no reliably curative treatment for reptile cryptosporidiosis. Options that have been used with varying success include:
- Paromomycin (100 mg/kg daily): Reduces oocyst shedding and may provide clinical improvement; must be given long-term
- Azithromycin (10 mg/kg every 48–72 hours): Occasionally used in combination
- Supportive care: Nutritional support (tube feeding with high-calorie reptile-specific diet), heat optimization (88–92°F warm side), hydration via soaks
- Nitazoxanide: Used in human medicine; emerging use in reptiles with anecdotal reports of improvement
Most affected geckos do not fully clear the infection. Some can be managed symptomatically for months to years; others deteriorate despite treatment.
Isolation is mandatory. Affected geckos must be permanently housed separately. All equipment, feeding tools, and enclosures should be considered contaminated.
An ARAV Reptile & Amphibian Resource, 2024 notes that biosecurity in leopard gecko collections — separating new animals for a minimum 60–90 day quarantine and PCR testing before introduction — is the most effective way to prevent Crypto from entering a gecko population.
When to See a Vet
Call your vet today if:
- Your leopard gecko's tail is visibly thinning despite eating normally
- You see undigested food regurgitated within a few hours of feeding
- Body weight has dropped more than 10–15% over 2–4 weeks
- You have recently acquired a new gecko and an existing gecko is now showing weight loss
Go to the ER immediately if:
- Your gecko appears completely exhausted, unable to lift its body, or is cold and unresponsive
- Severe bloating or abdominal swelling is present
- The gecko has not eaten at all for 2 or more weeks and is visibly wasting
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Frequently Asked Questions
How much does Crypto testing and treatment cost in leopard geckos? An exotic reptile vet visit runs $80–180. PCR fecal testing costs $60–120 per sample (3 samples recommended). Paromomycin treatment for several months costs $30–80 monthly. Nutritional support supplies add $20–50 monthly. Expect exotic vet rates of 1.5–2 times standard costs. Because Crypto is rarely curable, owners must also factor in quality-of-life decisions.
Can I get Cryptosporidium from my leopard gecko? C. varanii is considered species-specific to reptiles and is not known to infect immunocompetent humans. However, people with severely compromised immune systems (HIV/AIDS, transplant recipients, chemotherapy) should exercise caution and avoid handling fecal matter directly. Standard hand-washing after handling is sufficient for healthy adults.
Can other reptiles in my home catch Crypto from my gecko? Yes — C. varanii can infect other lizard species. Strict isolation, separate tools, and rigorous hand hygiene are essential. Oocysts survive for months in dry environments.
How can I tell if my gecko has Crypto versus just picky eating? A picky eater typically maintains or slowly gains weight between refusals. A gecko with Crypto continues to lose weight even when eating, and the tail becomes progressively thinner. Track body weight weekly with a kitchen scale — a documented downward trend with normal feeding behavior is a strong Crypto indicator.
Still Not Sure if Your Leopard Gecko Needs a Vet?
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