Eradication vs. Reality: Let's talk Measles and Understanding the Nuances in Public Health Terms

There were cases of Measles in 2000

In public health, the terms we use often carry weight and imply success, yet the reality can be far more nuanced than it appears at first glance. A prime example of this is the term "eradication" in the context of infectious diseases. Eradication is defined as the permanent reduction to zero of the worldwide incidence of an infection caused by a specific agent as a result of deliberate efforts, meaning that no further control measures are necessary. This is distinct from "elimination," which refers to reducing the incidence of a disease in a specific geographical area to zero, but requires ongoing measures to prevent re-establishment of the disease.

Consider the case of measles in the United States. In 2000, measles was declared eradicated from the U.S., indicating that there was no continuous disease transmission for more than 12 months within any specific geographic area. However, this declaration of eradication did not mean that no measles cases were reported in the country. In fact, in the same year, there were 86 reported cases. Of these, 26 (30%) were internationally imported. Among the remaining 60 indigenous cases, 18 were linked to these imported cases, nine were directly associated with imported virus, and 33 were of unknown origin.

These statistics highlight the global nature of infectious diseases and the ease of modern travel, which can quickly spread infectious agents across borders. Despite the eradication status, ongoing surveillance remains crucial to maintain this status by quickly responding to and containing outbreaks that arise, particularly those stemming from imported cases.

In 2000, there were 10 measles outbreaks in the U.S., defined as three or more confirmed cases, which occurred across nine states and accounted for 56% of the total cases that year. Notably, an epidemiologic link to an imported case was documented in half of these outbreaks.

This scenario underscores the importance of understanding the precise meanings behind terms like "eradication" and "elimination" and recognizing that even in a country where a disease is considered “eradicated”, vigilance and preventive health measures must continue to protect public health. It is also important to understand the true nature and the epidemiology of Measles now that is back in the news when we say things like “Measles” was eradicated from the USA in 2000, but “now there are new cases again”. There were cases in 2000 as well.

Source: https://www.cdc.gov/mmwr/preview/mmwrhtml/mm5106a2.htm