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Rare Diseases: FindZebra Search Engine

March 15, 2013

Why you ask, is an Internet search engine called FindZebra? In the medical community, the term “zebra” is used to refer to a rare disease or a surprising medical condition. When one goes to a physician seeking medical help, the first stage of diagnosis usually has the physician evaluating the patient’s symptoms against well-known common diseases. Rare conditions are not usually considered for an initial diagnosis. The widely used quote in medicine is, “If you hear hoofbeats, think horses, not zebras.”

FindZebra is an open-source search engine, that uses approximately 30,000 freely available medical articles focusing on rare and genetic diseases. It is developed at the Technical University of Denmark/University of Copenhagen. FindZebra recommends that only medical professionals should use it.

Using Google Search will give search results which can be composed of unverified information from content aggregators, blogs, and other possible unreliable sources. The FindZebra search engine results are from web resources containing only rare and genetic disease articles, and which are mostly maintained by medical professionals or patient organizations. FindZebra in head-to-head testing, outperforms Google Search for searching in rare diseases. Developers of the search engine FindZebra created a database using medical ontological information and the Unified Medical Language System (UMLS). FindZebra is similar to other standard web search engines and is easy to use by anyone familiar with performing web searches. Additional technical information about FindZebra’s search functionality can be found on the website.

A February 2013 article, “FindZebra: A search engine for rare diseases”, in the International Journal of Medical Informatics, compares Google Search with FindZebra. Fifty-six difficult real life diagnostic cases for rare diseases are used to compare both search engines. The conclusion of the journal article is that FindZebra outperforms Google Search and that the use of a specialized rare disease search engine can improve the diagnostic quality for healthcare professionals. The success of FindZebra is due to several factors :

  1. A dedicated customized rare disease search engine increases the quality of search results
  2. The use of specialized curated publicly available rare and genetic disease data sources
  3. Indexing of the data sources using UMLS (Unified Medical Language System) that is specific to medical concepts.

“A lesson of this study and similar work in this field, is that the ranking algorithm used by large-scale web search engines like Google are not optimized for particular unusual domains making it feasible to build improved specialized search engines.” The citation for this journal article :

FindZebra: A search engine for rare diseases. Radu Dragusin, Paula Petcu, Christina Lioma, Birger Larsen, Henrik L. Jørgensen, Ingemar J. Cox, Lars Kai Hansen, Peter Ingwersen, Ole Winther. International Journal of Medical Informatics. 26 February 2013 (10.1016/j.ijmedinf.2013.01.005) PMID: 23462700 [PubMed – as supplied by publisher].

The Pulmonary Hypertension Association (PHA) is making the zebra the symbol of a new 5-year campaign on the importance of considering a PH diagnosis early on. Since 2012, zebras have been the new symbol of the campaign. Pulmonary Hypertension (PH) patients and their families are using the zebra symbol by putting zebra stripes into their fundraising events and photos, and onto clothing. A 1-minute video from the organization uses the zebra symbol for the PH awareness campaign.

Please Note: “Three Zebras Drinking” by John Storr (Own work) [Public domain] | Wikimedia Commons.


Rare Disease Information Retrieval Project website at the Technical University of Denmark/University of Copenhagen

Hogan, Melissa ( “Virtual zeal: rare disease caregivers carry a powerful voice in social media”. PharmaPhorum (Viewed Online 03/14/13)

Nadel, Amy. “Rare Disease Day: Reflections From a Zebra Mom”. WebMD (Viewed Online 03/14/13).

Copyright © 2012-2013, Orphan Druganaut Blog. All rights reserved.

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