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Living with Pythiosis

A rare infection caused by a water-living organism that mostly affects animals and rarely people.

Understanding Pythiosis

Pythiosis is a disease caused by the water-living organism Pythium insidiosum that forms granulomas, or small clusters of inflammatory cells.

It occurs mainly in horses, cattle, dogs, cats, and fish, and rarely in people. It has three forms: eye (ocular), skin (cutaneous), and blood vessel (arterial).

Signs & symptoms

GARD doesn't list specific symptoms for this condition yet. The summary describes three forms:

  • Eye form (ocular)
  • Skin form (cutaneous)
  • Blood vessel form (arterial)

Not everyone has every symptom. GARD's list comes from the Human Phenotype Ontology.

Diagnosis

  1. Talk with your doctor

    Share the symptoms you've noticed, when they started and your family health history. Notes and photos can help.

  2. See a specialist

    Your doctor may refer you to a specialist who knows rare conditions.

  3. Ask which tests can help

    Your care team will decide which exams and tests can confirm the diagnosis.

Care & treatment

Care team
A doctor familiar with rare conditions, plus specialists as needed
Expert care
Ask about multidisciplinary care centers for rare conditions
Treatment
GARD doesn't list specific treatments for this condition. Your care team will tailor care to your symptoms.
Research
Clinical trials and observational studies may be options. See the research section below.

General information, not medical advice. Your care team makes the decisions.

Everyday life

Living with a rare condition is easier with support.

  • Connect with rare disease patient organizations for support
  • Keep notes on symptoms, changes and questions for appointments
  • Ask about patient registries that help research
  • Look into financial aid and travel resources for care visits
Bring these questions to your next doctor visit
Which form of pythiosis do I have?
How is it diagnosed and treated?
What exposures should I avoid in the future?

Quick facts

It is caused by the water-living organism Pythium insidiosum.

Also known as: human pythiosis; pythium insidiosum infection

Patient organizations

Rare-disease groups that can help

Source: NIH GARD · PythiosisGARD ID 11989 · GARD page updated September 2026 · Plain-language summary by Know Rare; editorial review pending. General information, not medical advice.

You are more than your diagnosis

Perspectives from people navigating life with Pythiosis.

Explore the Pythiosis blog

Explore research for Pythiosis

Explore actively recruiting Pythiosis studies with HealthSpark.

HealthSpark

Find actively recruiting studies for Pythiosis with HealthSpark. Share your city to explore research near you.

  • Recruiting studies from ClinicalTrials.gov
  • Share your city to look for research near you
  • Eligibility is confirmed by the study team

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I can help you find recruiting Pythiosis studies. Enter a ZIP code, address or city below and I'll look within 50 miles.

Powered by HealthSpark, our AI chat helper · Study information from ClinicalTrials.gov · Eligibility is confirmed by the study team.

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HealthStoryfor Pythiosis

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HealthStory evolves private journaling with a living AI journal that talks back and asks thoughtful questions, helping you capture your Pythiosis experiences more deeply and prepare for better conversations with your doctors and care team.

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