1976 Philadelphia legionellosis outbreak
Encyclopedia
The 1976 Philadelphia legionellosis outbreak was the first recognized outbreak of legionellosis
.
, where members of the American Legion
, a United States military veteran
s association, had gathered for the American Bicentennial. Within two days of the event’s start, veterans began falling ill with a then-unidentified pneumonia. They were tachypneic and complained of chest pain. As many as 221 people were given medical treatment, and 34 deaths occurred. At the time, the U.S. was debating the risk of a possible swine flu
epidemic, and this incident prompted the passage of a national swine flu vaccination
program. That cause was ruled out, and research continued for months, with various theories discussed in scientific and mass media that ranged from toxic chemicals to terrorism (domestic or foreign) aimed at the veterans.
The U.S. Centers for Disease Control and Prevention
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 legionellosis bacterium was finally identified and isolated, and found to be breeding in the cooling tower of the hotel’s air conditioning
system, which then spread it through the entire building. This finding prompted new regulations worldwide for climate control systems
.
Legionellosis
Legionellosis is a potentially fatal infectious disease caused by gram negative, aerobic bacteria belonging to the genus Legionella. Over 90% of legionellosis cases are caused by Legionella pneumophila, a ubiquitous aquatic organism that thrives in temperatures between , with an optimum temperature...
.
History
It occurred on July 27, 1976 at the Bellevue Stratford Hotel in Philadelphia, PennsylvaniaPhiladelphia, Pennsylvania
Philadelphia is the largest city in the Commonwealth of Pennsylvania and the county seat of Philadelphia County, with which it is coterminous. The city is located in the Northeastern United States along the Delaware and Schuylkill rivers. It is the fifth-most-populous city in the United States,...
, where members of the American Legion
American Legion
The American Legion is a mutual-aid organization of veterans of the United States armed forces chartered by the United States Congress. It was founded to benefit those veterans who served during a wartime period as defined by Congress...
, a United States military veteran
Veteran
A veteran is a person who has had long service or experience in a particular occupation or field; " A veteran of ..."...
s association, had gathered for the American Bicentennial. Within two days of the event’s start, veterans began falling ill with a then-unidentified pneumonia. They were tachypneic and complained of chest pain. As many as 221 people were given medical treatment, and 34 deaths occurred. At the time, the U.S. was debating the risk of a possible swine flu
Swine flu
Swine influenza, also called pig influenza, swine flu, hog flu and pig flu, is an infection by any one of several types of swine influenza virus. Swine influenza virus or S-OIV is any strain of the influenza family of viruses that is endemic in pigs...
epidemic, and this incident prompted the passage of a national swine flu vaccination
Vaccination
Vaccination is the administration of antigenic material to stimulate the immune system of an individual to develop adaptive immunity to a disease. Vaccines can prevent or ameliorate the effects of infection by many pathogens...
program. That cause was ruled out, and research continued for months, with various theories discussed in scientific and mass media that ranged from toxic chemicals to terrorism (domestic or foreign) aimed at the veterans.
The U.S. Centers for Disease Control and Prevention
Centers for Disease Control and Prevention
The Centers for Disease Control and Prevention are a United States federal agency under the Department of Health and Human Services headquartered in Druid Hills, unincorporated DeKalb County, Georgia, in Greater 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 legionellosis bacterium was finally identified and isolated, and found to be breeding in the cooling tower of the hotel’s air conditioning
Air conditioning
An air conditioner is a home appliance, system, or mechanism designed to dehumidify and extract heat from an area. The cooling is done using a simple refrigeration cycle...
system, which then spread it through the entire building. This finding prompted new regulations worldwide for climate control systems
HVAC
HVAC refers to technology of indoor or automotive environmental comfort. HVAC system design is a major subdiscipline of mechanical engineering, based on the principles of thermodynamics, fluid mechanics, and heat transfer...
.