I assume nothing. I see an increase in once eradicated diseases that coincides with an increase in illegals, especially young illegals entering the country, some being verified as carriers by border patrol. You can check vaccine records of everyone on every flight, but not everyone coming in across the border, unless you know something no one else does.
I never said I was talking about just measles. In fact, I don't think I singled out any single disease.
Correlation is not causation. And it doesn't matter what the disease is, though measles was the stimulus for this particular arc.
Those who get their medical advice from Jenny McCarthy needn't do anything. Let them die. Everyone else should get vaccinated.