The suddenly renewed debate over vaccinating children against communicable diseases is bound to be messy. It fills the already fraught territory of parenting with ideological landmines and a morass of non-scientists arguing over clinical research. So why not throw a little xenophobia into the mix?

The idea that the current outbreak of measles is the fault of undocumented immigrants crossing over from Mexico was raised Tuesday by Rep. Mo Brooks (R-Ala.), who told conservative radio host Matt Murphy that "illegal aliens" have clearly brought deadly diseases into America. "It might be the enterovirus that has a heavy presence in Central and South America that has caused deaths of American children over the past six to nine months," he said. "It might be this measles outbreak."

Dr. Ben Carson, a pediatric neurosurgeon and possible 2016 Republican presidential candidate, was more politic. Carson has already gone on record supporting stringent vaccination requirements, but he told CNN's Jake Tapper on Tuesday that "we have to account for the fact that we now have people coming into the country, sometimes undocumented people, who perhaps have diseases that we had under control," in this case measles.

Not only is that highly implausible, it's also a dangerous flirtation with politically expedient misdirection.

In fact, the current outbreak probably did originate outside the U.S., brought to Disneyland either by a visitor or an unvaccinated American who traveled abroad. The big measles outbreak of 2014, for example, was caused by an Amish missionary returning to a low-vaccination Ohio Amish enclave from the Philippines.

Dr. Anne Schuchat at the Centers for Disease Control and Prevention said that genetic testing of the Disneyland-linked virus shows similarities to strains of the measles found in Dubai, Qatar, Azerbaijan, and Indonesia. Even Joel Pollak at Breitbart News — in an article titled "Did Border Crisis Trigger Measles Outbreak?" — concludes that "the most plausible explanation" is that "a tourist present legally in the U.S. brought measles to the country while visiting."

Also, Mexico and Central America have pretty robust vaccination programs. In his radio interview, Rep. Brooks concern-trolls the "illegal aliens," kindly noting that they "have not been blessed with the kind of health care, the kind of immunizations that we demand of our children in the United States."

But that's nationalistic nonsense. According to World Health Organization estimates, the U.S. has a measles vaccination rate of 92 percent, while Mexico and Nicaragua have 99 percent vaccination rates and Honduras, Guatemala, and El Salvador each have 93 percent vaccination rates. If anything, those countries should be concerned about Americans coming down to visit.

More to the point, the blame for America's measles resurrection doesn't like outside our borders — it falls squarely inside them.

The decision on whether to vaccinate your children is personal, potentially emotional — and it is public, because as the new measles outbreak reminds us, it can prove life-threatening to other people's children as well. For me, as for most Americans, it is a no-brainer: Vaccinate your children. I have. So have Rand Paul and Chris Christie and the vast majority of American parents. Just not enough of them.

To achieve herd immunity, the point where a community isn't susceptible to measles outbreaks, at least 95 percent of the population has to be immunized. (It's complicated.) The U.S. national vaccination rate of 92 percent is reasonably protective, but it's a national average, and there are areas with much lower rates.

If 95 percent of Americans were immunized against measles, broadly across all communities, we wouldn't be talking about measles and vaccinations this week. And it wouldn't matter if phalanxes of unvaccinated, measles-carrying Central Americans crossed over into California — mild cases of the measles would spread, but the virus couldn't get a toehold.

The politics of vaccination are tricky — anti-vaccination fever is a bipartisan condition — but pretending this is the fault of "illegal immigrants" is pure and simple political opportunism, pandering and scapegoating by people who should know better and probably do.

There are a lot of fingers that can be pointed in this resurgence of a disease that should be eradicated by now, but those who are pointing them south of the border are part of the problem.