A viral post circulating online is making the far-reaching claim that six infectious diseases that have been eradicated are now spreading again and that "illegal immigrants" and "refugees" are the reason they are making a comeback.

The post says, "Six Eradicated Diseases are making a comeback thanks to refugees and illegal immigrants," with the alleged eradicated ailments as follows: Tuberculosis, measles, whooping cough, mumps, scarlet fever and the bubonic plague.

The post was flagged as part of Facebook’s efforts to combat false news and misinformation on its News Feed. (Read more about our partnership with Facebook.)

There are several things wrong with this claim.

To understand, we first should discuss what the term "eradication" means when it comes to infectious disease. A disease is "eradicated" when it is eliminated worldwide.

To date, only one disease that spreads among humans has been eradicated, according to the Centers for Disease Control and Prevention and the World Health Organization: smallpox.

The WHO declared smallpox eradicated in 1980 following a global immunization campaign and, according to the CDC, no cases of naturally occurring smallpox have been reported since 1977. (A second disease, rinderpest, has also been eradicated, but rinderpest spreads only among animals, not humans.)

When the incidence of a disease is reduced to zero in a particular geographical location such as a country or continent – as opposed to worldwide – virologists refer the disease as having been "eliminated" instead of "eradicated." So, a disease can be eliminated in a part of the world before it is completely eradicated.

Moreover, when the Facebook claim speaks of tuberculosis and scarlet fever as having been eradicated, it’s important to understand that only infectious diseases that already have measures in place to fight them are considered eradicable (for example, no vaccine currently exists for scarlet fever). Even then, experts say some are much more difficult to control than others.

Tuberculosis is indeed infectious and has a vaccine, but because the pathogen only needs 10 or fewer organisms (most need hundreds or thousands), it is slow-growing, and can take several months to show up in a lab test. So, not only has tuberculosis not been eradicated as the claim states, it is actually considered notoriously difficult to eradicate.

Third, of the six illnesses listed in this problematice Facebook post, only one – Measles – is on the CDC’s list of current outbreaks. Measles has never been eradicated, but it was declared "eliminated" from the United States in 2000. A recent resurgence of the disease, however, has grabbed lots of headlines.

Virologists at the CDC attribute the current U.S. outbreak, which includes the largest number of cases since 1992, to travelers (not necessarily immigrants) and those who refuse to get vaccinated:

"The U.S. experienced 17 outbreaks in 2018. Three outbreaks in New York State, New York City, and New Jersey, respectively, contributed to most of the cases. Cases in those states occurred primarily among unvaccinated people in Orthodox Jewish communities. These outbreaks were associated with travelers who brought measles back from Israel, where a large outbreak is occurring. Eighty-two people brought measles to the U.S. from other countries in 2018. This is the greatest number of imported cases since measles was eliminated from the U.S. in 2000."

Amy Rowland, spokesperson for the CDC’s Global Health Division, also told PolitiFact immigrants and refugees are not to blame for the outbreaks.

"No, it is not immigrants or refugees causing these outbreaks," Rowland said. "It has to do with travel and people who are not vaccinated or under-vaccinated. It has nothing to do with illegal immigrants."

Our ruling

A viral social media post claims that six eradicated diseases are making a comeback due to "refugees and illegal immigrants."

First, global health leaders have only ever declared one human disease has been declared eradicated, not six. And there is no evidence to back up the suggestion that refugees and undocumented immigrants are to blame for any disease making a comeback.

We rate this infectious post False.