History of Science, Technology & Medicine (HSTM) is the best database to use when looking for secondary sources -- scholarly journal articles, books, and dissertations -- in the history of science, medicine and technology.
Link your search terms using the AND connector. For example: typhoid and epidemic and yakima. On the search results screen, use the options on the left toolbar to narrow your search results. To find the fulltext of the article (if not provided directly in the database), click on the "Check for Full Text" button and work your way through the screens. Not all articles will be online, some may only be in print, others may not be available at the UW.