The Merck Manual is a standard medical source for reliable information. This link is to the Consumer Version, with a link on the page to the Professional Version for Health Care workers.
Information and links about the famous Johns Hopkins map. Note: It has been criticized for misleading data representation, specifically regarding the use of size of circles to show number of cases - many cases in a small area look like a larger area is affected.
Finding the most reliable information is extremely important when dealing with an epidemic.