When someone is diagnosed with certain infectious diseases that are reportable under state law, laboratories and healthcare providers report basic information, such as name and birthdate, of the diagnosed person (known as the “index case”) to the local and/or state public health agency.
Local public health epidemiologists use that information to contact and interview the diagnosed person. They ask the patient to try to remember everyone they may have been in close contact with while they were infectious. The epidemiologists then reach out to or contact those people, which is why they are called “contacts.”
To protect patient privacy, contacts are only informed that they may have been exposed to someone who had the infection. They are not told the identity of the patient who may have exposed them. All the interviews of contacts are voluntary. During the interviews, medical evaluation, treatment, and self-isolation are discussed and recommended, depending on the potential exposure to the disease.
Patients and contacts always get to decide how they will participate in this process, but public health staff are always grateful when they share as much information as possible because it helps lower the number of people who might get infected. Contact tracing helps people help others – it allows people to make informed decisions about their health, their potential exposures, and disease status, and allows them to take actions to protect themselves and others.
It is routinely done for infections such as HIV, pertussis, tuberculosis, salmonellosis, and gonorrhea.