evidence: One of our colleagues noticed that virtually every Washington Post article concerning the measles outbreak is followed by comments that link the outbreak to illegal immigration. As it turned out, a number of prominent politicians have suggested that there might be a link — or that a link cannot be ruled out. (LePage did not mention measles, but suggested there could be in "uptick" in other diseases.) [...] We should note that CDC’s Schuchat said that in 2014, "79 percent of the unvaccinated cases of measles in the U.S. were unvaccinated due to personal belief exceptions." So even if one could trace the source to an illegal immigrant, the main source of the problem is a failure to get vaccinated in the first place. [...] Unlike Limbaugh, Brooks and Carson did not draw a direct link between illegal immigration and the measles outbreak; they merely suggested it is a possibility. But it’s a tricky balance, given that thus far the CDC has not traced this most recent outbreak — or previous ones — to illegal immigration. One cannot have 100 percent certainty in life, and so that always leaves open the possibility of a link.