What is the Difference Between Control, Elimination and Eradication?

Control, Elimination, and Eradication of Disease

Key Terms: 

  • Disease control: A reduction in the incidence, prevalence, morbidity, or mortality of an infectious disease to a locally acceptable level
  • Disease elimination: A reduction to zero of the incidences of disease or infection in a defined geographical area
  • Disease eradication: Permanent reduction to zero of the worldwide incidence of infection

The definitions of disease reduction can tell you how preventative measures have affected the infection rate.

  • There is some confusion on which definitions of disease reduction require continued intervention measures such as vaccines.
    • Disease control: continued intervention measures are needed 
      • The measures prevent a spike in the cases on infection.
      • Infection still occurs, however, the rate of infection is low.
      • This means the current intervention measures are working and should be continued.
    • Disease elimination: continued intervention measures are needed
      • The measures prevent a re-introduction of cases.
      • There may not be any cases in the area, but the infection is present elsewhere.
      • This means the current intervention measures worked very well for the specific area and needs to be continued to keep the cases low.
    • Disease eradication: routine intervention measures are not needed
      • Once interruption of transmission of the disease is confirmed worldwide, a disease is eradicated.
      • Only 2 diseases have officially been eradicated: smallpox and rinderpest.

  • Even though cases are few to none, intervention measures are still very important. There are multiple ways diseases can travel from outside the area where the disease is eliminated.
    • Travel
      • A disease may be eliminated in a country, however, an infected individual from an endemic area could travel to the country and spark an outbreak if there wasn't continued interventions.
    • Animal Carriers (diseases can be carried by more than just humans)
      • Insects, livestock, and food products can carry diseases between countries and continents.
  • Due to the resiliency of these diseases, they spread locally, nationally, and internationally with ease.
    • This makes it difficult to eradicate a disease - which is why only 2 diseases have been declared eradicated.
    • Despite smallpox declared eradicated, smallpox vaccines are still stockpiled in case of an outbreak.
      • Even with eradicated viruses, great care is taken to be prepared with interventions.

Image source: Epidemics
Figure 1. Stages towards and after elimination in a given location and milestones on the path to elimination. In this figure, the post-elimination phase means that the incidence is low, however, has not reached the level of eradication yet. 

Intervention measures are necessary to maintain the low numbers and control the disease unless transmission has been completely interrupted worldwide.
  • In addition to disease control, elimination, and eradication, the CDC defines other terms used when discussing infectious diseases.
    • Elimination of disease: reduction to zero of the incidence of a specified disease in a defined geographical area from deliberate efforts. Continued intervention is required.
      • Example: neonatal tetanus
    • Elimination of infections: Reduction to zero of the incidence of infection caused by a specific agent in a defined geographical area from deliberate efforts. Continued intervention is required.
      • Example: measles, poliomyelitis
    • Extinction: The specific infectious agent no longer exists in nature or in the laboratory.
      • There are no examples of a disease that is extinct.
Intervention measures like vaccines are important no matter how common or uncommon the disease is; there is still a chance of infection.