About Zebra Scout
Why this exists
In 2023, a mother named Alex used ChatGPT to identify her son's condition — tethered cord syndrome — after 17 doctors over 3 years had failed to connect the dots. She didn't use AI to replace her doctors. She used it to ask better questions.
This is the diagnostic odyssey. On average, rare disease patients see 7.3 physicians over 4.8 years before getting a correct diagnosis. For some, it takes decades.
Zebra Scout exists because no parent should have to become a medical detective — but until the healthcare system catches up, tools that help people ask better questions can save years of suffering.
How it works
Zebra Scout uses a curated database of ~60 rare conditions and their associated symptoms, mapped to the Human Phenotype Ontology (HPO) — the standard medical vocabulary for describing clinical features.
When you enter symptoms, the tool:
- Maps your selected symptoms to HPO terms
- Compares them against the symptom profiles of known rare conditions
- Scores each condition using a weighted similarity algorithm (combining Jaccard similarity with condition coverage)
- Returns a ranked list of possible matches
All computation happens in your browser. No data is sent to any server. No accounts needed.
What this is NOT
- Not a diagnosis. Only a qualified medical professional can diagnose a condition.
- Not comprehensive. Our prototype database covers ~60 conditions. There are over 7,000 known rare diseases.
- Not a replacement for medical care. Use this to start a conversation, not to end one.
The data
Conditions and symptom mappings are curated from public sources including Orphanet, OMIM, and the HPO. This is a prototype — a production version would integrate these databases directly via their APIs.
Why “Zebra”?
There's a saying in medicine: “When you hear hoofbeats, think horses, not zebras.” It teaches doctors to consider common diagnoses first. But for rare disease patients, the answer really is the zebra — and that saying can become a barrier to diagnosis. The zebra stripe ribbon has become the symbol of the rare disease community.
Open source
Zebra Scout is part of the willworth monorepo. The data and matching algorithm are open source — contributions welcome.