Arya News - This summer marks the 50th anniversary of one of the most bizarre disease outbreaks in the history of microbiology – and one of the most consequential.
This summer marks the 50th anniversary of one of the most bizarre disease outbreaks in the history of microbiology – and one of the most consequential.
On July 21 1976, 2,300 delegates from the Pennsylvania section of the American Legion and their families (some 4,500 people in all) began arriving at the Bellevue-Stratford hotel in Philadelphia for the Legion’s annual four-day convention. Within four weeks, 29 people had died and 200 had been sent to hospital with “Legionnaires’ Disease”.
Then, as with outbreaks of measles today, the Legionnaires’ Disease outbreak coincided with celebrations marking the adoption of the Declaration of Independence. And then, as now, the United States was a deeply divided society and conspiracy theories were rampant.
For some, the fact that the outbreak occurred during the American Bicentennial and that many of the victims were veterans of World War II and Korea, was no accident.
Speculating that the “Philly killer”, as the press labelled the mysterious pathogen, was the work of a malign foreign power, the Philadelphia Veterans of Foreign Wars described it as “a sneak attack against the finest kind of Americans.”
Philadelphia’s mayor, Frank Rizzo, a tough talking former policeman and close friend of Richard Nixon, blamed activists opposed to the Vietnam War, while his spokesman, Albert Gaudiosi, suggested the outbreak might be the result of a covert CIA operation using chemical and biological weapons.
Today, we know better. After an exhaustive six-month investigation, in January 1977 the CDC announced it had isolated the infective agent – a common organism that grows readily in ponds and stagnant water, including the cooling towers of hotels.
Joseph Mullin of Philadelphia talks about his infection of the ‘mystery disease’ from his hospital bed, in August 1976 - BK/AP
Labelling the bacterium, Legionella pneumophila, the CDC speculated the organism had become aerosolised when water had been sprayed across the fill at the top of Bellevue-Stratford’s cooling tower, splintering the bacteria-rich film into tiny droplets.
It was thought that some of these droplets had been drawn into the air intake vents of the hotel’s air conditioning system and circulated throughout the hotel’s suites and bars where the droplets were drawn into delegates’ lungs.
Other droplets had cascaded down the side of the hotel, infecting people on the pavement.
Unfortunately, conclusive proof evaded the CDC as, by the time investigators had identified the organism, the cooling towers had been cleaned and Legionella from the water tower could not be recovered.
Despite this, following the outbreak at the Bellevue-Stratford public health agencies began routinely monitoring and testing water sources like cooling towers and plumbing for Legionella pneumophila and although the organism continues to spark occasional outbreaks , it no longer poses a major threat to public health and is no longer the subject of conspiracy theories.
If only the same were true of other pathogens whose source or cause has yet to be identified.
From Ebola to Covid-19 to hantavirus, epidemics of emerging and poorly understood infectious diseases are regularly linked to theories about bioweapons, population control and “lab leaks” , to name a few common conspiracy tropes. That they might be the result of natural processes and the by-product of climate change and alterations to the built environment is something that many people find hard to accept.
Why is this the case? Why do epidemics provoke so much mistrust and dissent? And what lessons does the 1976 Legionnaires’ Disease outbreak hold for the management of other outbreaks?
These are pertinent questions on the 250th anniversary of the Declaration of Independence.
It is an anniversary that is supposed to bring Americans together but judging by Trump’s intemperate Independence Day address at Mount Rushmore, in which he warned of a growing “communist menace”, Americans are more divided than ever.
Members of the Pennsylvania American Legion at a special congressional inquiry into the cause of the outbreak that killed 29 of their colleagues - Bettmann
Nature abhors a vacuum but conspiracy theories thrive when knowledge of epidemics is uncertain or wanting.
This is particularly true at times of epidemic crisis . Psychologically, it is comforting to believe that outbreaks happen for a reason. An invisible threat of unknown provenance challenges our sense of security, spreading fear and fuelling the search for alternative explanations.
In the pre-microbial era, before the birth of bacteriology and the science of epidemiology, the belief that epidemics were expressions of Divine wrath was a source of psychological comfort.
The solution was to repent one’s sins and cleave more keenly to religious strictures.
But when during the 14th century Black Death, recurrent outbreaks of bubonic plague reduced Europe’s population by between a third and a half, the punishment seemed disproportionate.
With their faith challenged, people looked for scapegoats, blaming Jews for poisoning the wells from which Christians drew their drinking water.
Later, observing that many epidemics originated in the East, this scapegoating was directed at the Chinese and other Asiatic peoples – hence the designation of cholera as the “yellow peril”.
By the early 19th century, as epidemiologists began to link infectious diseases to changing environmental and social conditions, such as poor sanitation and overcrowding, conspiracy theorists began to direct their ire at health authorities instead.
For instance, during the 1832 Parisian cholera epidemic, the German poet Heinrich Heine reported that the Parisian sanitary commission ordered mounds of rubbish that could be a source of contamination to be hauled beyond the city limits.
In response, ragmen who made their living sorting through the debris spread rumours that those who had died of cholera had been poisoned by the health authorities and took to the streets in protest.
“The more extraordinary these reports were, the more eagerly they were received by the multitude,” noted Heine in an echo of today’s coronavirus conspiracy theories.
Legionnaires’ survivor Charles Linn, 43, shares a quiet moment with his granddaughter prior to his discharge from hospital, in August 1976 - Fred Prouser/AP
Soon, physicians and surgeons who were perceived to be profiting from treatments and cures predicated on their science also became the focus of suspicion – hence the rumours that doctors, like the Edinburgh physicians Burke and Hare, were murdering cholera patients to harvest their bodies for medical dissection, or the rumours during the 1889 ‘Russian’ influenza epidemic that doctors were exaggerating the dangers of influenza to market quinine and other proprietary remedies.
And so it has continued to the present day with conspiracy theories claiming that Covid-19 is a ‘hoax’ designed to boost the uptake of vaccines.
Nor is there anything new about theories linking disease outbreaks to biowarfare. In 1918, the ‘Spanish’ influenza was blamed on biological weapons released by German U-boats and in the 1990s the KGB seeded a widely believed conspiracy theory that HIV had been engineered at a US military lab.
The appeal of these theories is that they offer a simple explanation for complex biological events. The same was true of the conspiracy theories surrounding the 1976 Legionnaire’s Disease outbreak.
The outbreak occurred just two years after Gerald Ford had assumed the presidency following Nixon’s resignation over the break-in at the Watergate building in Washington DC.
Coming in the wake of the Vietnam War, Watergate undermined trust in politicians and democratic institutions.
It didn’t help that in 1976, the US economy was in recession and consumers were still reeling from the 1973 oil embargo which, as with the Iran war and the closure of the Strait of Hormuz today, had sent energy prices soaring.
In 1964 the historian Richard Hofstadter had coined the term paranoid style to describe “the sense of heated exaggeration, suspiciousness and conspiratorial fantasy”, he detected in extreme right-wing movements, such as the 1964 campaign for the White House by Barry Goldwater, the militant anti-communist Republican senator from Arizona.
By the 1970s this paranoid style was arguably no longer confined to the Right but, following the assassination of leading lights of the civil rights movement, had also begun to infect the Left, hence the popularity of conspiracy theories blaming the deaths of Jack and Bobby Kennedy and Martin Luther King on variously the CIA, the Mafia and the Ku Klux Klan.
Nor did it help that in 1975 the Rockefeller Commission had revealed that the CIA had been conducting secret mind-control experiments using LSD and other chemical and psychological means.
Or that in 1972, a medical whistleblower had revealed the truth about the Tuskegee Syphilis Study, an unethical 40-year medical experiment in Alabama in which 600 impoverished African-American share-croppers had been allowed to develop untreated syphilis so that researchers could observe the natural progression of the disease.
Pennsylvania state police transfer specimens taken from the sick to a helicopter bound for a laboratory for analysis, in August 1976 - Paul Vathis/AP
On July 2 1976, two weeks before the outbreak at the Bellevue-Stratford, Ford had sought to unite the nation with a Bicentennial address in which he described the Declaration of Independence as “the Polaris of our political order – the fixed star of freedom”.
Ironically, given subsequent events, one of the few American institutions which still commanded wide public support at the time was the CDC.
In the 1950s, the agency had eliminated malaria from North America and spearheaded vaccination drives against polio and other diseases. And abroad, its Epidemic Intelligence Service (EIS) was at the frontline of the global campaign to eradicate smallpox – a campaign that would achieve its goal in 1980.
Thanks to these efforts and other public health initiatives, it seemed to many experts that infectious disease would soon be a problem of the past.
The Legionnaire’s Disease outbreak, followed by the outbreak of HIV/Aids six years later shattered that hubristic conviction.
Deploying classic epidemiological methods, David Fraser, the head of the CDC’s Special Pathogens Branch, ordered his officers to compile line lists of the victims at the Bellevue-Stratford and map the distribution of the infections in time and space.
The disease, whatever it was, caused an aggressive form of pneumonia but laboratory tests for influenza and common bacterial causes of pneumonia, such as psittacosis and Q fever, proved negative.
Not knowing whether the pathogen was airborne or transmitted via food and/or water, Fraser ordered EIS officers to comb the hotel’s suites and conference rooms for common environmental and chemical contaminants.
They began by checking the cadmium pitchers in which bar staff had mixed the Legionnaires’ Bloody Mary’s (cadmium poisoning resembles influenza).
Next, they swept the elevators and hospitality suites. But once again the tests were negative.
The longer the mystery remained unresolved the wilder the speculation became.
Veterans carry the casket of Legionnaires’ victim J.B. Ralph from funeral home in Williamstown, Pennsylvania, in August 1976 - Paul Vathis/AP
Perhaps the Legionnaires had been exposed to phosgene gas, a pulmonary agent first deployed by the Germans in World War I and which causes choking and shortness of breath.
Or perhaps they had been poisoned with nickel carbonyl, a highly toxic liquid that can trigger chemical pneumonia and cardiorespiratory failure.
By December, Fraser was at a loss.
“The illness resembles an infectious disease, but there is no secondary spread and microbiological studies have been negative,” he admitted in his final report on the outbreak.
“No toxin is known that causes just this pattern of disease and toxicological studies are also negative so far.”
Despairing of finding the pathogen, Robert Sharrar, chief of communicable disease control for Philadelphia, described the outbreak as “the epidemiological puzzle of the century”.
It didn’t help that by now the search for the pathogen was in danger of being overshadowed by the fiasco over what became known as the “swine flu affair”.
Four months before the outbreak at the Bellevue-Stratford, the US Army had isolated a new strain of swine influenza at Fort Dix, New Jersey.
Worried that it might be a pandemic strain similar to the 1918 ‘Spanish’ influenza, scientists at the CDC and other agencies persuaded Ford to immunise millions of Americans.
But in the event the swine flu proved no more severe than a regular seasonal influenza, prompting criticism that the threat had been hyped for the benefit of pharmaceutical companies.
Pennsylvania’s Secretary of Health Dr Leonard Bachman updates a press conference on the outbreak, in August 1976 - Fred Prouser/AP
It took a low-ranking CDC microbiologist to solve the mystery of the Legionnaires’ outbreak.
Stung by the criticism of the CDC, Joseph McDade had returned to his laboratory shortly after Christmas determined to have another go at identifying the pathogen.
A specialist in rickettsial diseases, McDade had fairly limited experience in public health microbiology, much less the politics surrounding major disease outbreaks.
But his lack of expertise would work in his favour, prompting him to depart from standard laboratory procedures and conventional patterns of thought.
While examining smears of liver sections from guinea pigs inoculated with lung tissue from Legionnaires’ patients, McDade had noticed occasional clusters of peculiar rod-shaped bacteria.
On a hunch, he applied a stain that had been developed for rickettsial organisms in the hope of bringing the bacteria into sharper view.
Then, having allowed the bacteria to grow freely in the liver tissue, McDade injected the material into chicken egg embryos.
The embryos immediately started to die and when McDade stained the tissue he found the same rod-shaped bacteria growing in clusters.
The final proof came when he mixed the organism with serum from Legionnaires’ patients and the bacteria “lit up”, signalling a strong antibody reaction.
McDade’s breakthrough is a classic example of the importance of scientists thinking outside the box.
Dr Bachman with a chart detailing Legionnaires’ cases, in August 1976 - Paul Vathis/AP
The reason other CDC microbiologists had missed the Legionella organisms is that they did not react to standard bacterial stains.
But McDade was a novice to public health microbiology and had not been schooled in the same thought processes and techniques as his colleagues.
Instead, he used a stain that no one else had considered. In this regard, he represented an exception to Pasteur’s dictum that “fortune favours the prepared mind”.
The discovery of Legionella pneumophila enabled Fraser to account for the peculiar epidemiological pattern observed at the Bellevue-Stratford.
During the latter stages of the investigation, suspicion had centred on leaky refrigeration units in the basement of the hotel.
One theory was that coolant from the units could have got into the air vents or elevator shafts and become overheated, causing the release of phosgene gas.
After further outbreaks of Legionnaires’ Disease in the summer of 1977, however, it was established that Legionella (there are some 23 species in all) thrive in the cooling towers of large buildings.
Under normal conditions, water rarely reaches the temperatures necessary for the bacteria to multiply.
However, when temperatures rise the organism grows more readily and if the towers are not serviced regularly they can be drawn into intake vents and air shafts.
The American Legion convention had opened to sweltering conditions and the following day, July 22, there had been a sharp temperature inversion.
The result was that the towers on the roof of the hotel had become superheated.
In other words, the epidemic was very much the product of modern technology and the built urban environment.
The current Ebola outbreak in DRC is also the subject of conspiracy theories - BENEDICTION MURHABAZI/AFP via Getty Images
Another lesson is that although cooling towers are now regularly inspected for Legionella, climate change increases the likelihood of superheating events.
To be sure, every now and again these controls fail and there are fresh outbreaks – last year, for instance, an outbreak at Harlem Hospital and a nearby construction site resulted in 90 people requiring hospital treatment and seven deaths.
But there is no longer any mystery about the cause and the outbreaks are no longer the subject of conspiracy theories.
Sadly, this is not true of other pathogens.
The ongoing Ebola outbreak in the Democratic Republic of the Congo is a case in point.
Although scientists have long known about the threat posed by the Bundibugyo strain of the virus, there is currently no vaccine for it and, like other types of Ebola, it is not known where the virus resides between outbreaks (the leading suspects are fruit bats).
The result is that the outbreak has become a fertile ground for conspiracy theorists, hence claims that it is a hoax got up by DRC health authorities to attract foreign aid.
The failure to recover SARS-CoV-2, the virus of Covid-19, from animals sold at the Huanan wet market in Wuhan – the likely ground zero of the outbreak – has fuelled similar conspiracy theories, as well as unproven claims that the pandemic is the result of experiments on related Sars viruses at the Wuhan Virology Institute.
As Don DeLillo observed in his novel ‘Libra’ about the life of Lee Harvey Oswald and his participation in a fictional CIA conspiracy to assassinate President Kennedy, conspiracy theories “gleam like jade idols”.
Employing 20/20 hindsight, they are seductive precisely they provide simple, easy-to-understand explanations for seismic cultural events.
When the events coincide with significant anniversaries and periods of political turmoil – and expert knowledge is wanting - it is natural for people to look elsewhere for explanations.
The problem is that, unlike in 1976 when Ford trusted the CDC to solve the Legionnaires’ mystery, today its capacity to launch similar outbreak investigations has been severely reduced by Trump’s cuts to the agency and his amplification of conspiracy theories about Covid-19.
Sad to say, the biggest threat to our ability to control infectious disease outbreaks no longer comes from pathogens but from the President himself.
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