1976 Philadelphia Legionnaires' Disease Outbreak
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The 1976 Legionnaires' disease outbreak, occurring in the late summer in
Philadelphia Philadelphia ( ), colloquially referred to as Philly, is the List of municipalities in Pennsylvania, most populous city in the U.S. state of Pennsylvania and the List of United States cities by population, sixth-most populous city in the Unit ...
,
Pennsylvania Pennsylvania, officially the Commonwealth of Pennsylvania, is a U.S. state, state spanning the Mid-Atlantic (United States), Mid-Atlantic, Northeastern United States, Northeastern, Appalachian, and Great Lakes region, Great Lakes regions o ...
, United States at an annual
American Legion The American Legion, commonly known as the Legion, is an Voluntary association, organization of United States, U.S. war veterans headquartered in Indianapolis, Indiana. It comprises U.S. state, state, Territories of the United States, U.S. terr ...
convention, was the first occasion in which a
cluster may refer to: Science and technology Astronomy * Cluster (spacecraft), constellation of four European Space Agency spacecraft * Cluster II (spacecraft), a European Space Agency mission to study the magnetosphere * Asteroid cluster, a small ...
of a particular type of pneumonia cases were determined to be caused by the ''
Legionella pneumophila ''Legionella pneumophila'', the primary causative agent for Legionnaires' disease, Legionnaire's disease, is an Aerobic organism, aerobic, pleomorphic, Flagellum, flagellated, non-spore-forming, Gram-negative bacteria, Gram-negative bacterium. ' ...
'' bacteria. Previous outbreaks were retroactively diagnosed as being most probably caused by Legionella bacteria.


Background

On July 21, 1976, the
American Legion The American Legion, commonly known as the Legion, is an Voluntary association, organization of United States, U.S. war veterans headquartered in Indianapolis, Indiana. It comprises U.S. state, state, Territories of the United States, U.S. terr ...
opened its annual three-day convention at the
Bellevue-Stratford Hotel The Bellevue-Stratford Hotel is a landmark building at 200 S. Broad Street (Philadelphia), Broad Street at the corner of Walnut Street (Philadelphia), Walnut Street in Center City, Philadelphia, Center City Philadelphia, Pennsylvania. Construct ...
in
Philadelphia, Pennsylvania Philadelphia ( ), colloquially referred to as Philly, is the List of municipalities in Pennsylvania, most populous city in the U.S. state of Pennsylvania and the List of United States cities by population, sixth-most populous city in the Unit ...
. More than 2,000 Legionnaires, mostly men, attended the convention. The date and city were chosen to coincide with America's celebration of the 200th anniversary of the signing of the
US Declaration of Independence The Declaration of Independence, formally The unanimous Declaration of the thirteen States of America in the original printing, is the founding document of the United States. On July 4, 1776, it was adopted unanimously by the Second Continen ...
at Philadelphia in 1776. On July 27, three days after the convention ended, Legionnaire Ray Brennan, a 61-year-old retired
US Air Force The United States Air Force (USAF) is the Air force, air service branch of the United States Department of Defense. It is one of the six United States Armed Forces and one of the eight uniformed services of the United States. Tracing its ori ...
captain Captain is a title, an appellative for the commanding officer of a military unit; the supreme leader or highest rank officer of a navy ship, merchant ship, aeroplane, spacecraft, or other vessel; or the commander of a port, fire or police depa ...
employed as a Legion bookkeeper, died at his home of an apparent
heart attack A myocardial infarction (MI), commonly known as a heart attack, occurs when Ischemia, blood flow decreases or stops in one of the coronary arteries of the heart, causing infarction (tissue death) to the heart muscle. The most common symptom ...
. Brennan had returned home from the convention on the evening of July 24 complaining of feeling tired. On July 30, another Legionnaire, Frank Aveni, aged 60, also died of an apparent heart attack, as did three other Legionnaires. All of them had been convention attendees. Twenty-four hours later, on August 1, six more Legionnaires died. They ranged in age from 39 to 82, and, like the five previous victims, all had complained of tiredness, chest pains, lung congestion, and fever. Three of the Legionnaires had been patients of Dr. Ernest Campbell, a physician in
Bloomsburg, Pennsylvania Bloomsburg is the only incorporated town in Columbia County, Pennsylvania, United States, of which it is also the county seat. It is part of Northeastern Pennsylvania and is located southwest of Wilkes-Barre, Pennsylvania, Wilkes-Barre along ...
, who noticed that the only common link between the three was that they had attended the convention. He contacted the Pennsylvania Department of Health. Officials at the American Legion also began getting notices of the sudden deaths of several members, all at the same time. Within a week, more than 130 people, mostly men, had been hospitalized, and 25 were reported dead. In total, there were 149 Legionnaires who became sick and 33 other persons associated with the hotel or in the area who also became sick. Of these 182 cases, 29 persons died.


Epidemiology

The U.S.
Center for Disease Control The Centers for Disease Control and Prevention (CDC) is the national public health agency of the United States. It is a United States federal agency under the Department of Health and Human Services (HHS), and is headquartered in Atlanta, ...
mounted an unprecedented investigation and, by September, the focus had shifted from outside causes, such as a disease carrier, to the hotel environment itself. In January 1977, the ''
Legionella ''Legionella'' is a genus of gram-negative bacteria, gram-negative bacteria that can be seen using a silver stain or grown in a special media that contains cysteine, an amino acid. It is known to cause legionellosis (all illnesses caused by ''Legi ...
'' bacterium was finally identified and isolated and was found to be breeding in the cooling tower of the hotel's
air conditioning Air conditioning, often abbreviated as A/C (US) or air con (UK), is the process of removing heat from an enclosed space to achieve a more comfortable interior temperature, and in some cases, also controlling the humidity of internal air. Air c ...
system, which then spread it through the building. This finding prompted new regulations worldwide for climate control systems. Complicating the situation was a fear among the public that the original cluster of 14 cases, six of whom died within a few days of each other, represented an outbreak of
swine flu Swine influenza is an infection caused by any of several types of swine influenza viruses. Swine influenza virus (SIV) or swine-origin influenza virus (S-OIV) refers to any strain of the influenza family of viruses that is endemic in pigs. As ...
. The total number of cases reached 211, and of those, 29 had died. At the time of the outbreak, epidemiological investigation protocols did not include active participation by both laboratory specialists and investigators. No effective communication existed between scientists in the field interviewing patients, and those in the laboratory testing specimens. File:Gorman and Feeley.jpg,
Centers for Disease Control The Centers for Disease Control and Prevention (CDC) is the national public health agency of the United States. It is a United States federal agency under the Department of Health and Human Services (HHS), and is headquartered in Atlanta, ...
medical technologist George Gorman (''left'') and Jim Feeley, examining culture plates upon which the first environmental isolates of ''Legionella pneumophila'' had been grown


Discovery of Legionella pneumophila

While the
Center for Disease Control The Centers for Disease Control and Prevention (CDC) is the national public health agency of the United States. It is a United States federal agency under the Department of Health and Human Services (HHS), and is headquartered in Atlanta, ...
(as it was called in that era) responded rapidly, as did the Pennsylvania Health Department, it took six months for the CDC microbiologist Joseph McDade to discover the cause of the outbreak. He initially thought the cause was viral because blood and tissues from the patients failed to grow bacteria when incubated in culture medium. His subsequent attempts to isolate the viral agent in eggs included antibiotics to kill off "contaminating" bacteria. It was only when he omitted the antibiotics that the bacteria grew in eggs. Attempts to reproduce the disease in mice, the standard laboratory animal model, also failed. The disease was finally produced in guinea pigs. The CDC announced the discovery at a press conference on January 18, 1977. The bacterium was later named ''
Legionella pneumophila ''Legionella pneumophila'', the primary causative agent for Legionnaires' disease, Legionnaire's disease, is an Aerobic organism, aerobic, pleomorphic, Flagellum, flagellated, non-spore-forming, Gram-negative bacteria, Gram-negative bacterium. ' ...
''. ''Legionella pneumophila'' is the most common cause, but sometimes other species of Legionella bacteria also cause Legionnaires' disease. The terms "Philadelphia fever" and "Legion fever" appear to have been used at the time of the outbreak and for shortly thereafter, although at least one 2008 source which covers disease in a historical narrative sense also included "Legion Fever" as alternate name. Both the World Health Organization in 2018 and the United States Center for Disease Control and Prevention (CDC) in 2017 only use the term Legionnaires' disease to refer to the serious version with pneumonia.


Retrospective diagnosis of earlier outbreaks as Legionnaires' disease

CDC investigators quickly discovered outbreaks of respiratory disease caused by ''L. pneumophila'' dating back to 1959. * An outbreak of what was dubbed
Pontiac fever Pontiac fever is an acute, nonfatal respiratory disease caused by various species of Gram-negative bacteria in the genus ''Legionella''. It causes a mild upper respiratory infection that resembles acute influenza. Pontiac fever resolves spontaneo ...
occurred in a health department in
Pontiac, Michigan Pontiac ( ') is a city in and the county seat of Oakland County, Michigan, Oakland County in the U.S. state of Michigan. Located roughly northwest of downtown Detroit, Pontiac is part of the Metro Detroit, Detroit metropolitan area, and is vari ...
in July 1967. No one died. Although caused by the same bacterium, Pontiac fever is a milder ailment than Legionnaires' disease. Pneumonia is absent in those with Pontiac fever. * An outbreak of pneumonia in July–August 1965, at
St. Elizabeths Hospital St. Elizabeths Hospital is a psychiatric hospital in Southeast, Washington, D.C., Southeast Washington, D.C. operated by the District of Columbia Department of Mental Health. The hospital opened in 1855 under the name Government Hospital for th ...
in Washington, DC, which killed 16 persons out of 78 infected was later determined to be Legionnaires' disease. * A September 1974 convention of the
Independent Order of Odd Fellows The Independent Order of Odd Fellows (IOOF) is a non-political, non-sectarian international fraternal order of Odd Fellowship. It was founded in 1819 by Thomas Wildey in Baltimore, Maryland, United States. Evolving from the Odd Fellows, Order ...
was also held at the very same Bellevue-Stratford Hotel. Out of approximately 1,500 members who attended, 20 developed pneumonia and two died. A later article in ''
The Lancet ''The Lancet'' is a weekly peer-reviewed general medical journal, founded in England in 1823. It is one of the world's highest-impact academic journals and also one of the oldest medical journals still in publication. The journal publishes ...
'' reported: "Illness igh fever and pneumoniawas significantly associated with attendance at one convention activity held on Monday morning, September 16, 1974, in the grand ballroom of the hotel." Oddly, staff members of the hotel seemed immune to infection and the CDC has yet to discover the reason for this apparent immunity.


See also

* 1999 Bovenkarspel legionellosis outbreak *
Legionella pneumophila ''Legionella pneumophila'', the primary causative agent for Legionnaires' disease, Legionnaire's disease, is an Aerobic organism, aerobic, pleomorphic, Flagellum, flagellated, non-spore-forming, Gram-negative bacteria, Gram-negative bacterium. ' ...
*
Legionnaires' disease Legionnaires' disease is a form of atypical pneumonia caused by any species of ''Legionella'' bacteria, quite often ''Legionella pneumophila''. Signs and symptoms include cough, shortness of breath, high fever, myalgia, muscle pains, and headach ...
* List of Legionellosis outbreaks


References


External links

{{DEFAULTSORT:Philadelphia Legionellosis outbreak 1976 disease outbreaks Philadelphia Legionnaires' disease outbreak 1976 disasters in the United States 1970s in Philadelphia American Legion Building biology Health in Pennsylvania Disasters in Pennsylvania 1976 Philadelphia Legionnaires disease outbreak Industrial hygiene Legionellosis July 1976 in the United States