Thursday, November 13, 2014

WHO: Legionnaire’s Disease Outbreak – Portugal


Legionella Bacteria - Photo Credit CDC PHIL

# 9319


Over the past few days I’ve noticed a few stories regarding an expanding outbreak of Legionnaire’s Disease in a suburb of Lisbon, Portugal.  Today, based on the rapid growth and unusually large size of the outbreak, the World Health Organization has issued the following Disease Outbreak News report.


Legionnaires' disease – Portugal

Disease outbreak news
13 November 2014

On 9 November 2014, WHO was notified by the National IHR Focal Point for Portugal of a large outbreak of Legionnaires' disease in Vila Franca de Xira, a suburban area of Lisbon.

Details of the cases are as follows:

The first 17 cases were identified between 6 and 7 November. Since then, the number of cases has increased exponentially. On 12 November, the Directorate-General for Health of Portugal reported a total of 302 cases of Legionnaires' disease. So far, 5 deaths have been confirmed to be caused by the disease. Four more deaths are currently being investigated. All cases have epidemiological links to the outbreak taking place in Vila Franca de Xira.

This is the biggest Legionella disease outbreak detected in Portugal, and it is evolving rapidly; therefore, the outbreak is considered to be a major public health emergency.

At present, the regional outbreak investigation team is in place and it is supported by a larger national team of experts in epidemiology, clinical, microbiology and environmental health, with other stakeholders from the municipality following the epidemiological situation and undertaking environmental investigations.

Precautionary measures

As precautionary measures, ornamental fountains in the outbreak area have been closed, and the chlorine concentration of tap water has been increased. Cooling towers of the main industrial facilities in the affected area have been closed down.

The Directorate-General for Health of Portugal has issued the following precautionary recommendations to the population, until the source of the outbreak has been identified and eliminated:

  • to avoid showers, Jacuzzis and whirlpools;
  • to disinfect shower heads by immersion in bleach solutions for about 30 minutes once a week,
  • to set the temperature on water heaters above 75ºC, if possible.

The Directorate-General for Health is liaising with the national agencies for health, environment and meteorology. It is also maintaining close communication and collaboration with partners in the European Union – especially, the European Centre for Disease Prevention and Control (ECDC) – and with the World Health Organization. WHO Regional Office for Europe and its Centre for Environment and Health in Bonn, Germany have been fully informed, and stand ready to mobilise experts, if required.



While an infectious pneumonia, Legionella is not considered a contagious disease.  It is transmitted environmentally. The bacteria thrives in warm water, such as is often found in air-conditioning cooling towers, hot tubs, and even ornamental water fountains. Improper maintenance or poor design can lead to the bacteria blooming.


When water is sprayed into the air the bacteria can become airborne, and if inhaled by a susceptible host, can cause a serious (and sometimes fatal) form of pneumonia.


While large outbreaks of Legionella are often traced to specific causes, quite often the source of the infection for sporadic cases remains a mystery.


Legionella got it’s name after it was identified as the bacterial cause of a large pneumonia outbreak at Philadelphia’s Bellevue Stratford Hotel during an American Legion convention in 1976. During this outbreak, 221 people were treated and 34 died.


We now know Legionella to be a major cause of infectious pneumonia, and that it can sometimes spark large outbreaks of illness. 


According to the CDC between 8,000 and 18,000 Americans are hospitalized with Legionnaire's Disease each year, although many more milder cases likely occur. For background information on the disease, the CDC maintains a fact sheet at Patient Facts: Learn More about Legionnaires' disease.

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