They raise the risk for every damned disease under the sun. Three years ago, the DFW metroplex became home to a new bug, an upper respiratory thing that lasts and lasts, stronger than a round or Zpack. Feels like an cold, then the flu, then allergies, then a cold, etc... I've lived here all my life, and this thing only showed up recently. Coincidentally or not, back a few years ago, an attentive observer could notice an increasing number of "recent immigrants" sitting like a sack of taters, obviously ill, in places like the barber shop, laundromat, horking up mouthfuls of infected phlegm.
The issue of importing diseases into our crowded cities is the one issue I'm watching as the ultimate barometer of how the American public will deal with illegal immigration. Jobs, driver's lisences, voting...to the extent that those are issues, they aren't personal like an unprecedented sinus infection that will not go away. If we don't respond aggressively and decisively (whatever that means, in the long run) to this threat to our very bodily health, then we deserve to vanish like other native populations erased by imported disease.
This is also the one issue that could finally awaken the more sensitive of our citizens (Soccer Moms, for example) to the realities of what the heck is going on. No decent mother will turn a blind eye to potential health risks to her children. 'Course, this all presumes that at some point, real figures of "new, unprecedent, exotic" infections liked to illegals will become commonplace in the PC media. Not holding my breath, since most immigrant-related news stories still are designed to elicit sympathy for the immigrants.
Your vote is being countered by that of an illegal, your car insurance is going through the roof because uninsured illegals are flooding our streets, you're getting sick in strange and unusual ways because illegals are bringing in diseases for which you have no immunity. And your politicians feign ignorance as they pander for votes and cheap labor.