Surveillance is a critical tool in infection prevention and control, used to monitor disease trends and guide public health responses. The Certification Board of Infection Control and Epidemiology (CBIC) emphasizes the "Surveillance and Epidemiologic Investigation" domain, which aligns with the Centers for Disease Control and Prevention (CDC) "Principles of Epidemiology in Public Health Practice" (3rd Edition, 2012). The question describes a process of collecting and analyzing indicators to signal an increase in community illness, requiring identification of the appropriate surveillance type among the options provided.

Option C, "Syndromic," is the correct answer. Syndromic surveillance involves monitoring non-specific health indicators or symptoms (e.g., fever, respiratory complaints, or gastrointestinal issues) that may precede a formal diagnosis, aiming to detect potential outbreaks or increases in community illness early. The CDC defines syndromic surveillance as the real-time or near-real-time collection, analysis, and interpretation of health-related data to provide actionable information, often in collaboration with public health agencies. This approach uses data from sources like emergency department visits, over-the-counter medication sales, or absenteeism reports to identify trends before laboratory confirmation, making it well-suited to the described scenario of signaling community illness increases.

Option A, "Passive," involves healthcare providers or laboratories reporting cases to public health authorities on a voluntary or mandatory basis without active prompting (e.g., routine notifiable disease reporting). While passive surveillance contributes to baseline data, it is less proactive and not specifically designed to signal early increases in illness, making it less fitting. Option B, "Active," entails public health officials actively seeking data from healthcare facilities or providers (e.g., calling to confirm cases during an outbreak). This is more resource-intensive and typically used for specific investigations rather than ongoing community trend monitoring, which aligns better with syndromic methods. Option D, "Targeted," refers to surveillance focused on a specific population, disease, or event (e.g., monitoring TB in a high-risk group). The scenario’s broad focus on community illness indicators does not suggest a targeted approach.

The CBIC Practice Analysis (2022) and CDC guidelines highlight syndromic surveillance as a key strategy for early detection of community-wide health threats, often involving collaboration with public health agencies. Option C best matches the described activity of analyzing indicators to signal illness increases, making it the correct choice.