In late January 1930, President Herbert Hoover placed an embargo on parrots, banning all of the colorful birds from America’s ports of entry. The reason? Disease prevention.

For weeks, cases of a deadly disease called “parrot fever” had made headlines across the United States. One of the first reported victims was a woman named Lillian Martin, who had received a pet parrot from her husband over the holidays. Shortly after, the bird fell ill and died—and Mrs. Martin (as well as two members of her family, who had helped care for the ailing bird) began showing symptoms of a mysterious illness that resembled typhoid.

As a doctor examined the family, he recalled reading about parrot fever in a newspaper and immediately suspected Martin might have the rare disease. He sent a telegram to the U.S. Public Heath Service asking if they had a serum to treat it. They did not.

This was a serious problem. Parrot fever is a very real disease—and an unpleasant one at that. Caused by the bacteria Chlamydia psittaci, parrot fever (or psittacosis) can be contracted after coming into close contact with infected parrots, pigeons, ducks, gulls, chickens, turkeys, and dozens of other bird species. The symptoms resemble pneumonia or typhoid fever, with victims suffering from extremely low white blood cell counts, high fevers, pounding headaches, and respiratory problems. Today the disease can be treated with antibiotics, but in 1930, 20 percent of victims were expected to die.

The story of parrot fever, however, would prove to spread much faster than the disease itself. Only a few days into January, four people became gravely ill at the same Baltimore pet shop from which Martin's bird had been purchased, and parrot fever was immediately suspected as the cause. The U.S. Public Health Service tasked a pathologist named Charles Armstrong with finding a cure.

According to an NPR interview with The New Yorker writer Jill Lepore, “Armstrong decide[d] that the way to gather information about this outbreak is to cable all the public health departments in every American state and in cities where they are now cropping up suspected cases. What he needs to do to solve the mystery is to spread the word.”

Armstrong's effort to stop the disease, however, had consequences: It sowed panic. On January 8, The Washington Post wrote: "'Parrot' Disease Baffles Experts."

Newspapers went nuts. As Lepore explained in The New Yorker, parrot fever had all the makings of a viral story: It was unheard of, foreign, exotic, and invisible—and, if real, it threatened to harm the whole country. The AP forebodingly called it a “new and mysterious enemy.” Doctors across the country, who were told to be on the lookout for signs of the disease, seemed to start blaming every unusual cough on possible psittacosis. By mid-January, more than 50 cases of parrot fever—including eight deaths—had been reported.

By January 18, California had enacted a 60-day embargo, banning parrots from the port of San Pedro. (Any bird that managed to cross the border in time was placed under quarantine.) One week later, President Herbert Hoover followed suit, issuing an executive order stating that “No parrot may be introduced into the United States or any of its possessions or dependencies from any foreign port.”

Many newspapers took the embargo as validation. “If you have a darling pet parrot, do not bury your nose or mouth in its pretty feathers, or stroke the parrot and afterward put your hand to your mouth,” warned Arthur Brisbane in his nationally syndicated editorial column. But many experts also argued that the embargo was reactionary and that fears were widely overblown. (Some went so far to wrongly claim that parrot fever didn’t exist at all.)

The Surgeon General, Hugh S. Cummings, landed squarely in the middle of the debate. In a full-page column, he tried to calm the public’s fears: “The present outbreak of the disease among human beings is not at all likely to assume the proportions of a widespread epidemic,” he wrote. Unfortunately, he didn’t succeed in calming anyone down. (In the same article, Cummings managed to call parrots “a dealer of death,” which didn't really help his case.)

Naturally, some people refused to take any risks. Lepore wrote:

“Before it was over, an admiral in the U.S. Navy ordered sailors at sea to cast their pet parrots into the ocean. One city health commissioner urged everyone who owned a parrot to wring its neck. People abandoned their pet parrots on the streets.”

By November of 1930, the number of parrot fever cases had dwindled and the ban was finally lifted. To this day, there’s still controversy over how many reported cases of parrot fever were genuine and how many were merely the result of mass suggestion.

“There has always been a doubt in the mind of the public as to whether or not the parrot was guilty; but a parrot was an acceptable ‘goat,’ and he bore the brunt of the accusation," The Montana Standard reported the day after the ban was lifted. “We may import all the parrots we please, and Polly can now screech her desire for a cracker, with no fear of any official demanding her naturalization papers.”