Dr. Alison, one of CDC’s disease detectives, interviews Eddie’s family, primary care providers, and friends while at the hospital. Eddie’s family and primary care providers describe Eddie’s clinical signs and symptoms, such as fever (measured temperature of 100°F or greater), cough, and muscle aches.
They also provide information about Eddie’s other health condition, asthma. Preexisting health conditions, like asthma, can put a person at a higher risk for developing severe disease. Eddie’s friends provide information on what activities Eddie was involved with at the Thomas County Fair. They provide important epidemiologic information on place (i.e., the geographic location of where Eddie recently visited, such as visiting the animal areas at the fair); and time (i.e., when Eddie may have been exposed and infected), such as before or during the Thomas County Fair and when Eddie started showing clinical signs and symptoms of infection.
After collecting some initial information, Dr. Alison and the other disease detectives work together to create a case definition. They will use the case definition to see if anyone else who is ill should be included in the investigation.
A case definition is a set of uniformly applied criteria for determining whether an event (e.g., disease or injury) should be considered as part of the outbreak. A case definition often includes medical features (e.g., clinical signs and symptoms), epidemiologic information, and laboratory test results. Epidemiologic information can include criteria on the demographic characteristics such as sex and age (i.e., person), geographic location of where an ill person lives or visited recently (i.e., place), and onset of clinical signs and symptoms (i.e., time).
