Of the 52 case-seeking reports posted on Epi-X during calendar year 2010, all were posted with the intent of seeking cases of illness caused by infectious disease. One report was broad based and also sought cases of illness caused by injury. These reports were categorized by type of infectious agent, depending upon commonality of symptoms and routes of transmission. Epi-X contributors posted case-seeking reports for 19 individual confirmed or suspected infectious agents in 2010. The top four infectious agents for which case-seeking reports were posted on Epi-X in 2010 were Salmonella (10 reports), Legionella (9), hepatitis A virus (4) and measles virus (4) . Other infectious agents included Influenza, Bordetella, Cryptosporidium, Escherichia coli and Listeria. Three reports were posted for which the infectious agent was unknown.