Conservative media frequently push the debunked claim that immigrants pose a threat to public health, merely changing the disease to fit their narrative. Fox News repackaged a popular nativist and anti-immigrant smear claiming that the child migrants from Central America were “an illegal health risk” and were bringing diseases into the country according to internal CDC emails.

On the April 25 edition of Fox News' Fox & Friends, anchor Heather Nauert reported that “disease” had come with the “thousands of immigrant children” who came to the United States in 2014, fleeing violence from their home countries. The assertion was based on documents recently made public by the conservative activist group Judicial Watch showing officials from the Centers for Disease Control (CDC) coordinating responses for the possibility of unaccompanied minors arriving with tuberculosis:

While the CDC acknowledged that “a small number of cases of TB have been identified,” it also noted that “CDC believes the unaccompanied children arriving from Central America pose little risk of spreading infectious diseases to the general public.”

Similar claims to Fox News' have been debunked by experts previously. In 2015 the fact-checking website PolitiFact examined Republican presidential front-runner Donald Trump's claim that “tremendous infectious disease is pouring across the border” and wrote that “The experts we contacted agreed that there is no evidence of a massive influx of infections across the border” as a consequence of undocumented immigration. An NBC News report explained that, in fact, most of the illnesses found in unaccompanied child immigrants were “nothing unusual,” including the common cold and head lice. NBC also noted that mechanisms were put in place so that arrivals are screened for tuberculosis -- which is not casually transmitted -- and facilities with the capacity to quarantine were made available. According to the most recent data from the World Health Organization, immunization rates for tuberculosis in Central America are above 80 percent. Tuberculosis in the United States has had a declining incidence for decades, with a relatively small increase of 157 more cases in 2015, which, according to the CDC, cannot be pinned on a single variable like undocumented immigration, since funding for prevention has been reduced or stagnant nationwide.

However, the trope of immigrants carrying diseases to the United States is often perpetuated by anti-immigrant and nativist groups hoping to stoke fear and resentment towards immigrants. According to one expert, “There is a long, sad and shameful tradition in the United States in using fear of disease, contagion and contamination to stigmatize immigrants and foreigners.” Fox News and other conservative media figures -- including Rush Limbaugh and Laura Ingraham -- have pushed this smear, blaming immigrants for diseases that range from leprosy, measles, chickenpox, and dengue to enterovirus and ebola, despite the absence of evidence showing a significant correlation. The Southern Poverty Law Center has explained that these claims “generally originate with modern nativist groups and ideologues.” They are then presented by right-wing media as factual news, without the benefit of context or the opinions of experts that have explained how the threat that undocumented immigrants place on public health is "wildly overstated."