Largest Outbreak of Legionnaires’ Disease in the UK

Phillidelphia 1976: First Outbreak of Legionnaires’ Disease

People most at risk

How Legionnaires’ Disease is diagnosed

Largest Outbreak of Legionnaires’ Disease in the UK

In August 2002, seven members of the public died and 180 people suffered ill health as a result of an outbreak of legionella at a council-owned arts and leisure facility in the town centre of Barrow-in-Furness, Cumbria.

The coroner for Furness and South Cumbria criticised the council for its failings with regard to health and safety at the conclusion of an inquest into the seven deaths. In 2006, council employee Gillian Beckingham and employer Barrow Borough Council were cleared of seven charges of manslaughter, but both admitted breaching the Health and Safety at Work Act. Beckingham, the council senior architect ultimately responsible for health and safety at the centre, was fined £15,000 and the authority £125,000. The borough council was the first public body in the country to have faced corporate manslaughter charges.

Following the court case, two public meetings were held to allow members of the public, and those affected, to learn more about the circumstances and the causes of the outbreak. The Barrow Legionnaires’ Outbreak Public Meetings were held on 4 and 11 December 2006 at Abbey House Hotel, Barrow. They were chaired by former West Lancashire MP Colin Pickthall.

The purpose of the following report is to record the content of those meetings and to allow others to learn what caused the outbreak and what changes have been made since. It has also been produced to allow dutyholders with similar responsibilities for controlling legionella to benefit from the findings of the investigation and be able to apply the recommendations identified as a result of the tragedy. The report explains both the technical steps, and the essentials of good health and safety management that can make sure a similar tragedy never happens again.

Click here to see the report of the public meetings into the legionella outbreak in Barrow-in-Furness, August 2002.

Philadelphia, United States, 1976

The first recognized outbreak occurred on July 27, 1976 at the Bellevue Stratford Hotel in Philadelphia, Pennsylvania, where members of the American Legion, a United States military veterans 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.

People most at risk

People most at risk of getting sick from the bacteria are older people (usually 50 years of age or older), as well as people who are current or former smokers, or those who have a chronic lung disease (like emphysema). Legionnaires’ disease can be very serious and can cause death in up to 5% to 30% of cases. Most cases can be treated successfully with antibiotics [drugs that kill bacteria in the body], and healthy people usually recover from infection.

People who have weak immune systems from diseases like cancer, diabetes, or kidney failure are also more likely to get sick from Legionella bacteria. People who take drugs to suppress (weaken) the immune system (like after a transplant operation or chemotherapy) are also at higher risk.

How is Legionnaires’ disease diagnosed?

Most people with Legionnaires’ disease will have pneumonia (lung infection) since the Legionella bacteria grow and thrive in the lungs.  Pneumonia is confirmed either by chest x-ray or clinical diagnosis.  Several laboratory tests can be used to detect the Legionella bacteria within the body.  The most commonly used laboratory test for diagnosis is the urinary antigen test, which detects Legionella bacteria from a urine specimen, or sample.  If the patient has pneumonia and the test is positive, then the patient is considered to have Legionnaires’ disease.

Additionally, if the Legionella bacteria are cultured (isolated and grown on a special media) from a lung biopsy specimen, respiratory secretions, or various other sites, the diagnosis of Legionnaires’ disease is also considered confirmed.  Finally, paired sera (blood specimens) that show a specific increase in antibody levels when drawn shortly after illness and several weeks following recovery, can also be used to confirm the diagnosis.

The table below shows the difference in symptoms and severity between Legionnaires’ Disease and the less serious but similar Pontiac fever.

Legionnaires’ disease Pontiac fever
Clinical Features Pneumonia: cough, fever, chest pain Flu-like illness (fever, chills, malaise) without pneumonia
Radiographic pneumonia Yes No
Incubation period 2-14 days after exposure 24-48 hours after exposure
Etiologic agent Legionella species Legionella species
Attack rate* < 5% > 90%
Isolation of organism Possible Virtually never

Hospitalization common

Case-fatality rate: 5-30%**

Hospitalization uncommon

Case-fatality rate: 0%

* Percent of persons who, when exposed to the source of an outbreak, become ill.

** Percent of persons who die from Legionnaires’ disease or Pontiac fever.