From the about page:
FindZebra is a specialised search engine supporting medical professionals in diagnosing difficult patient cases. Rare diseases are especially difficult to diagnose and this online medical search engines comes in support of medical personnel looking for diagnostic hypotheses. With a simple and consistent interface across all devices, it can be easily used as an aid tool at the time and place where medical decisions are made. The retrieved information is collected from reputable sources across the internet storing public medical articles on rare and genetic diseases.
A search engine with: WARNING! This is a research project to be used only by medical professionals.
To avoid overwhelming researchers with search result “noise,” FindZebra deliberately restricts the content it indexes.
An illustration of the crudeness of current search algorithms that altering the inputs is the easiest way to improve outcomes for particular types of searches.
That seems to be an argument in favor of smaller than enterprise search engines, which could roll-up into broader search applications.
Of course, with a topic map you could retain the division between departments even as you roll-up the content into broader search applications.