Step 1: Act on notification of illness is the first action in the investigation. Which option correctly states this step?

• A. Develop a working case definition
• B. Act on notification of illness
• C. Provide information
• D. Submit report

Answer: (B)

The first action when a notice of illness comes in is to act on that notification. This immediate response starts the investigation and protects people by quickly validating the report, gathering essential details (who is ill, where, when, and what symptoms), and initiating the initial steps of the response. Acting now sets the stage for the rest of the process—confirming that an outbreak is happening, developing a working case definition, and implementing control measures—because you need real information from the outset to shape those later actions. If you wait, cases could continue to occur and the situation could get worse. The other steps are important, but they rely on having that initial notification action and the information it triggers.