...Start with the Irish, who were accused of spreading cholera through American cities in the early 1800s. Then came the Chinese, charged with bringing smallpox, leprosy and bubonic plague to California. Writing in 1862, one doctor warned that Chinese immigrants would “corrode the vitals of our strength and prosperity.” Indeed, he added, their threat to the public health was greater than if “the hordes of Genghis Khan should overflow the land.”

In 1900, after a Chinese man died of plague, health officials in San Francisco quarantined 25,000 Chinese residents in a 15-block section of the city. Chinese and Japanese travelers were barred from railroads unless they had received a newly developed — and largely untested — inoculation against the disease. At least one local newspaper suggested a simpler solution: burn down Chinatown. “Clear the foul spot from San Francisco,” the paper urged, “and give the debris to the flames.”

Then came the Italians, with their “low foreheads” and “weak chins,” as sociologist E. A. Ross wrote in 1914. Small wonder that they so often got sick, which threatened others with illness as well. In New York, Ross noted, Italian immigrants’ death rate was twice that of the general population.

Actually, as historian Alan Kraut has shown, the Italian mortality rate was lower than the New York average. Likewise, Jews — who were accused of spreading tuberculosis — had one of the lowest rates of death from the disease of any ethnic group. But anti-Semites continued to denounce them as sickly weaklings — “the polar opposite of our pioneer brand,” E.A. Ross scowled — who would supposedly weaken everyone else. 

More recently, Haitian immigrants were one of the “4 H’s” — alongside homosexuals, heroin users and hemophiliacs — deemed at risk for AIDS by the Centers for Disease Control in 1983. As one physician admitted two years later, when the CDCremoved Haitians from the list, they were “the only risk group that were identified because of who they were rather than what they did.”

But that’s been the historic pattern. And we’re witnessing it again, in the calls to keep out migrants from Ebola-affected nations in Africa. Of course we should screen visitors from these countries for the virus, as the CDC is already doing at five airports. And we should also work with African immigrant communities to help them identify people who might have been infected with Ebola or exposed to it...