Disease Epidemic

Picture of child with measles

What is an epidemic?

Anytime we see more people ill from a certain cause than we would expect it is considered an epidemic (a.k.a. outbreak).

  • If we expect 0 cases of an illness (e.g., Smallpox), then 1 case is an epidemic.
  • If we expect 15-30 cases of a disease (e.g., Tuberculosis) then it might take 50 or 100 cases to be considered an epidemic.

Our epidemiologists conduct surveillance to monitor rates of certain diseases. When they discover that we have a potential epidemic they investigate and get involved, when necessary, to stop the epidemic.

What will the health department do to respond to an epidemic?

If our area were to experience an epidemic of certain contagious diseases it might become necessary to give vaccines or treatments (like antibiotics) to a large number of people in the community.

Depending on the disease and the population affected, the Health District may decide to distribute the vaccine or medication only to a particular population, such as people with certain risk factors. Conversely, it could be decided that all residents should receive the medication or vaccine, depending on availability. Those decisions will be based on needs and risk factors, not on race, language, disability, income, or status.

Picture of petri dishes and doctor

Some diseases that could cause epidemics are listed below. Click on the links for more information.

Fact Sheets

Some infectious diseases (like Anthrax and Plague) are normally rare in humans. Epidemics of such diseases might indicate bioterrorism. Get more information on bioterrorism.