The Legionnaires’ outbreak in Philly 50 years ago led to months of mystery — and gave the disease its name

As Philadelphia wallowed in self-pity over its seemingly botched Bicentennial celebrations 50 years ago, thousands of American Legion members arrived for a late July convention at the Bellevue-Stratford Hotel.

Weeks later, dozens of them were dead from a mystery ailment, and scores of others were sickened. The victims, authorities said, returned home to develop respiratory infections that in some instances progressed to fatal cases of pneumonia.

For more than half a year, local and federal health authorities were unable to determine what killed them, resulting in a web of fear, paranoia, and frustration that gripped not only Philadelphia, but also the nation at large.

This was the infamous Legionnaires’ disease outbreak of 1976, perhaps the blackest of marks on Philadelphia’s record for the year. Today, the disease — known as legionellosis, caused by Legionella pneumophila bacteria — still crops up, most recently in a 50-building outbreak in Manhattan that has so far caused at least six deaths.

Philadelphia was not the last, or even the first, city to experience the disease. But that outbreak half a century ago is how it got its name. Here is how The Inquirer and Daily News covered it:

About 2,000 American Legion delegates came to town for a convention that ran from July 21 to 24, 1976, at the iconic Bellevue-Stratford Hotel. There were no signs of trouble during the convention, or for several days afterward.

But by early August, about a week after the convention’s end, 14 Pennsylvania American Legion members were dead of an unclear illness, with their deaths involving “some type of respiratory problem,” reports from the time indicate. Roughly 50 others were reportedly hospitalized.

Many of the initial victims were from Western Pennsylvania and had traveled to the city, though some Philadelphians were among the sick and dead. All had attended the American Legion convention the month before, officials said.

As officials mounted an investigation that cost the state $25,000 a day, the death toll continued to increase. By mid-August, 29 people were dead and about 200 were sickened, reports indicate.

The Centers for Disease Control said at the time that the outbreak was “without precedent” in the agency’s 30-year existence, and began conducting laboratory work to determine the cause.

“We have not seen anything like this take place in such a short period of time,” said Jay Satz, chief virologist with the Pennsylvania Department of Health. “This is something to be quite concerned about.”

Health officials largely expected the cause to be a then-long-awaited epidemic of swine flu, which had killed a soldier at Fort Dix in New Jersey earlier in the year, and focused much of the investigation on identifying that disease, reports indicate. Other possible causes, including toxins such as nickel carbonyl, were also considered.

But public speculation about the cause, as well as how the disease arrived in the city, ran rampant. Or, as The Inquirer put it at one point, there were more people who had “their own ideas on what is causing the mysterious disease than there are Kennedy assassination conspiracy theories.”

Inquirer readers wrongly blamed everything from pigeon droppings to contaminated ice. One person claimed the trash piling up on city streets, thanks to a municipal worker slowdown at the time, was the reason. Another contended shellfish was the cause, noting that “mostly men had been stricken because women don’t like shellfish.”

Others believed the cause was more nefarious. Surely the disease had come from communists from Ecuador or Poland, who intentionally spread it to American Legion members. No, it was a sneak attack staged by the potentially disruptive activist groups Mayor Frank Rizzo had warned about.

The American Legion, meanwhile, did not believe foul play was involved — nor did investigators, who said no evidence supported any of these theories. The truth, it seemed, was far less salacious.

» READ MORE: Frank Rizzo wanted federal troops to patrol Bicentennial protests. They ‘neither came nor were needed.’

As worry over the illness wore on, the Bellevue-Stratford hotel itself also fell victim to the disease’s impacts, closing in November 1976.

Though investigators avoided directly implicating the hotel early on, it suffered severe financial damage. Reservations collapsed into single-digit occupancy percentages, resulting in losses of up to $10,000 per day, reports from the time indicate. William G. Chadwick, the hotel’s vice president and general manager, said business had been devastated.

“We have found it impossible any longer to withstand the economic impact of the worldwide adverse publicity which has been associated with the Legionnaires’ disease,” he said.

By then, the Bellevue had operated for more than 70 years and was considered a jewel in the city’s hospitality crown. Its closure, Rizzo said, was a “great loss,” and he vowed the property would host a new, modern hotel to fill the gap. Today, it is a mixed-used development at 200 S. Broad St. that includes a hotel portion.

Philadelphia’s Bicentennial tourist business also suffered, with several conventions canceling their bookings over fear of the illness, significantly affecting what was expected to be a banner year for visitors. Public perception erred on the side of avoiding the city, which some local officials tried to rebut.

“We are still a safe city,” said Eugene Hosmer, director of the Philadelphia Convention and Visitors Bureau, noting the disease struck just as low civic self-esteem seemed to be fading. And then, “we’re hit with this.”

Robert Jacob, manager of the Penn Center Inn and head of the Greater Philadelphia Hotel Association, put the illness’ impact more dramatically.

“We’re being crucified,” he said.

» READ MORE: The Bicentennial didn’t go as expected. But it wasn’t exactly as bad as Philadelphians say it was.

Investigators searched for months for the disease’s cause to no avail, facing substantial criticism — including a congressional subcommittee hearing during which their efforts were labeled an “embarrassment,” according to reports from the time.

But in January 1977, after tens of thousands of tests, investigators identified the culprit. The deadly Legionnaires’ disease, the CDC found, was caused not by a toxin or virus, but a bacterium. One so strange and unknown, lab workers and scientists had missed it for months.

Credited with its discovery was Joseph McDade, then a CDC microbiologist in the agency’s leprosy and rickettsia laboratory. On a hunch after receiving a routine report, McDade reexamined slide samples and decided to look for unfamiliar microbe shapes. And he found them — and they appeared not only in samples from Philadelphia, but also in past unsolved outbreaks.

The disease was found to be present in samples from a 1965 pneumonia outbreak at St. Elizabeth’s Hospital in Washington, in which 18 people died, and a 1968 one that sickened 144 people at a Pontiac, Mich., health department building. Additionally, the illness had struck a 1974 Independent Order of Odd Fellows convention in an outbreak that killed two people — also held at the Bellevue-Stratford.

Investigators later determined the 1976 outbreak had been spread via airborne water mist from the hotel’s air-conditioning cooling towers. The towers allowed the bacteria to grow and be spread to convention attendees, as well as some individuals who had traveled near the hotel, investigators found.

“We are dealing with a very real phenomenon which has been present in the past but has never been recognized,” said CDC director David Sencer in 1977. “We now know what to look for.”