Certification Board of Infection Control and Epidemiology (CBIC) Practice Exam 2025 – The All-in-One Guide for Exam Success

The term that refers to the fraction of a population having a specific disease at a given time is prevalence. Prevalence is a key epidemiological measure that indicates how widespread a disease is within a population. It takes into account both new and existing cases of the disease, providing a snapshot of its burden at a specific moment.

For instance, when public health officials report the prevalence of a disease, they often present it as a percentage or a number per a defined population size, which helps in understanding the extent of the disease and planning appropriate health interventions.

Incidence, in contrast, focuses on the number of new cases that occur in a specific time period, rather than the total number of cases. The rate of spread generally refers to how quickly an illness propagates through a population, while attack rate quantifies the frequency of new cases in a specific, often defined outbreak situation. These terms serve different purposes within epidemiology, with prevalence specifically summarizing the total burden of disease at a particular time.