Measles would likely be the first eradicated disease to return, because it is so highly contagious, but other diseases like rubella, diphtheria and polio could also return if vaccination rates fall by half, according to the models.

Measles could become endemic in the United States if routine childhood vaccination rates continue to decline, with up to 51 million illnesses over a 25-year period, according to a new study.

LA County health officials are investigating a case of measles involving a resident who recently traveled from Texas. This, as an outbreak in West Texas has now ballooned to nearly 650 cases, and as public health experts warn that the viral infection could again become endemic,