ECDC: Rapid Risk Assessment On Portugal’s Legionnaire’s Disease Outbreak

 

Credit ECDC

 

# 9322

 

Yesterday, in WHO: Legionnaire’s Disease Outbreak – Portugal, we saw the official announcement of one of the largest outbreaks of Legionella that we’ve seen inyears; more than 300 cases in a week’s time.  While not a record (Murcia, Spain saw 800+ cases in 2001), this is a very large cluster, and the outbreak is ongoing.

 

Based on the size and rapid growth of the cluster, the WHO called it a `major public health emergency’.  But Legionnaire’s is not a communicable disease, and so the threat is limited to those who are directly exposed to the environmental source of the bacteria.

 

The Legionella bacteria thrives in warm water, such as is commonly found in air-conditioning cooling towers, hot tubs, and even ornamental water fountains. When water is sprayed into the air the bacteria can become aerosolized and inhaled.

 

Those who are susceptible (often smokers, immunocompromised, elderly, etc.) can develop serious – even life threatening – pneumonia.

 

Today the ECDC has produced a Rapid Risk Assessment for the rest of the EU, which includes a good deal of background on Legionnaire’s disease.  I’ve only posted some excerpts, click the link to download the entire PDF.

 

 

RAPID RISK ASSESSMENT

Outbreak of Legionnaires’ disease in the Lisbon area, Portugal

13 November 2014

ECDC threat assessment for the EU

The large number of cases in a short period of time suggests an environmental source that has spread contaminated aerosols in the area. The Portuguese authorities are focusing the environmental investigation on such a possibility. Since 9 November they have implemented precautionary measures in closing cooling towers of major industrial installations in the area of Vila Franca de Xira. People who have been in the affected area in the past three weeks (longest documented incubation period is 19 days) may therefore have been at risk of infection, and could be currently incubating the disease and may develop symptoms up to three weeks after exposure.

People with underlying illness or a weakened immune system are at increased risk of developing the disease if exposed and may present with more severe disease.

Since Legionnaires’ disease cannot be transmitted from person-to-person, the risk remains limited to people who have been possibly exposed in the affected area during the period when the bacteria was spread in the environment. Travellers who have visited Vila Franca de Xira in the past three weeks and who develop symptoms of Legionnaires’ disease should seek rapid medical advice and indicate their possible exposure.

The health authorities in Portugal have kept the public informed through regular press releases and local information sessions about the disease and exposure risks.

To date, no cases associated with this outbreak have been detected outside of Portugal. The suspected cases reported in Peru and Angola were further excluded for Legionella. Legionnaires’ disease cases that are detected outside of Portugal and who match the case definition (see Annex 2) should be reported through ELDSNet (eldsnet@ecdc.europa.eu).

Conclusions

The outbreak of Legionnaires’ disease in Portugal with 311 cases reported as of 13 November 2014 is one of the largest in the European Union. Vila Franca de Xira is not considered a tourist destination and no case has so far been confirmed outside Portugal. Despite the magnitude of the outbreak, this event can be considered a local event. All cases were infected in Vila Franca de Xira where the outbreak is occurring.

Cooling towers of major industrial installations in the area of Vila Franca de Xira were closed and investigations to identify the source of the outbreak are ongoing.

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.

UK: Probable Source Of Legionnaires Outbreak Indentified

Legionella Bacteria - Photo Credit CDC PHIL

 

# 6461

 

The outbreak of Legionella in the UK I wrote about last week (see HPA Updates The Stoke-On-Trent Legionella Outbreak) has expanded to 18 cases, and today the HPA has announced that they believe they have tracked down the bacteria’s source.

 

It appears that 17 of the 18 cases visited a JTF Mega Discount Warehouse where hot tubs were displayed and sold.  Genetic fingerprinting has determined that the same strain of Legionella found in these patients was present in the hot tub.

 

As this was a unique strain, not previously encountered, the odds are pretty good they’ve found the source.

 

The legionella 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 aerated the bacteria can become airborne, and if inhaled by a susceptible host, can cause a serious (and sometimes fatal) form of pneumonia. 

 

This update comes from the HPA.

 

 

Stoke-on-Trent Legionnaires’ Disease Outbreak – probable source identified

30 July 2012

Public and environmental health experts investigating the Legionnaires’ disease outbreak at Stoke-on-Trent believe they have identified a probable source.

 

The probable source is a hot tub based at JTF Warehouse, City Road, Fenton, Stoke-on-Trent. We would like to emphasise that investigations are still ongoing. Environmental Health specialists from the Health and Safety Executive and Stoke-on-Trent City Council have taken and continue to take samples from sites across Stoke.

 

A spokesperson from the Health and Safety Executive said: "HSE continues to inspect premises where we are the enforcing authority and will do so until we have eliminated those sites from our investigations and are sufficiently assured there are no other possible sources."

 

The samples from the hot tub at JTF Warehouse were confirmed by the Health Protection Agency’s specialist laboratory in Colindale last night as being an unusual strain legionella bacteria. The strain matched those taken from patients. JTF warehouse are fully cooperating with the investigation.

 

Dr Sue Ibbotson, regional director, Health Protection Agency West Midlands said: “We have identified the probable source of the Legionnaires' disease outbreak in Stoke. We have the evidence from DNA fingerprinting of samples from the hot tub and the patients being caused by the same previously unseen strain of legionella. The HPA also took detailed histories from the confirmed cases and we know that 17 of the 18 confirmed cases visited this warehouse in the two weeks before they fell ill. Added to that we know that spa pools are known to be effective mechanisms for spreading legionella infection.

 

“We may still expect to see new cases of Legionnaires’ disease related to this outbreak. JTF Warehouse decommissioned the hot tub on 24 July. It can take up to two weeks following exposure for people to develop symptoms of Legionnaires’ disease and a further few days before they go to see their GP. We continue to work with our partners to investigate this outbreak and continue to take samples across the city in case there are other sites with the same strain of legionnella.”

(Continue . . . )

 

For an even more unusual source of Legionella, you may wish to revisit a blog from 2010 where we looked at a Study: Wiper Fluid And Legionella.

HPA Updates The Stoke-On-Trent Legionella Outbreak

 

Legionella Bacteria - Photo Credit CDC PHIL

# 6450

 

Yesterday Crof reported on the UK: Legionnaires' disease outbreak in Stoke-on-Trent that involved 7 patients hailing from that city in Staffordshire, England.

 

Today, we’ve an update from the HPA indicates that two more cases have been identified, and that early microbiology testing is consistent with there being an (as yet, unidentified) common source.

 

 

3.00pm update on Legionnaires' disease in Stoke-on-Trent

25 July 2012

Two further case of Legionnaires' disease have been confirmed in the Stoke-on-Trent outbreak bringing the total number of cases to nine. All those affected are between their late 40s and mid 70s and are being treated at University Hospital of North Staffordshire. The Health Protection Agency (HPA) is also investigating two cases identified in early summer as being possibly linked to the current cluster.

 

Professor Harsh Duggal, Director of the Health Protection Unit in Stafford, said: “Early microbiology typing results back from the HPA laboratories show that samples taken from some of the patients look very similar so far and this is consistent with the cases having caught their infection from the same environmental source. We are taking detailed histories of the movements of the patients to see if there are similar patterns which would indicate a local source of infection.

(Continue . . . )

 

 

While an infectious pneumonia, Legionella is not a contagious disease.  It is transmitted environmentally, usually through water.

 

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 more information on the disease, the CDC maintains a fact sheet at Patient Facts: Learn More about Legionnaires' disease.

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.  

 

Today’s HPA announcement stresses that these cases are not hospital acquired, and that the authorities are working to identify the source.

ECDC: Risk Assessment On Edinburgh Legionella Outbreak

 

 

# 6386

 

 

This morning the ECDC published a brief Rapid Risk Assessment on the Legionella outbreak in Scotland that has been ongoing for about two weeks (for earlier reports see here, and here).

 

According to NHS Lothian, which is the local public health authority running point on the investigation, the number of cases has remained steady over the past couple of days at 88 (see Update - 13/06/2012).  

 

Yesterday Health Secretary Nicola Sturgeon was quoted as saying:

 

“These numbers today again offer reassurance that the worst of the outbreak is over. The increase of confirmed cases and reduction in the suspected cases is in line with our expectations. However, there is no room for complacency and we will continue to monitor the situation very closely over the coming days.

 

A link to the 4-page ECDC risk assessment, and a few excerpts, follows:

 

Rapid risk assessment: A community outbreak of Legionnaires' disease in Edinburgh, Scotland

Technical reports - 14 Jun 2012

Available as PDF in the following languages:

 

This document is free of charge.

ABSTRACT

ECDC assessed the risk to the EU related to the community outbreak of Legionnaires' disease in Edinburgh, Scotland.

In the absence of an identified and controlled source of Legionella, there may be an ongoing risk of exposure for persons living or visiting the area, although the risk is assessed to be low for the general public due to implemented control measures.

 

Main conclusions and recommendations

Eighty-eight cases of Legionnaires’ disease, of which one was fatal, have occurred in the south-western part of Edinburgh since 24 May 2012 when the first case was reported to have fallen ill.

Although the exact source of the outbreak has not yet been identified, the clustering of cases in the south-western part of Edinburgh and the evolving number of cases suggests an ongoing source in this part of the city. Environmental investigations to confirm the source and treatment of local cooling towers in the area are ongoing. The  implementation of precautionary control measures at any identified suspected  risk installations
are of utmost importance to decrease the risk of exposure.

 

In the absence of an identified and controlled source of Legionella, there may be an ongoing risk of exposure to  Legionella  for persons living or visiting the area, although the risk is assessed to be low for the general public due to implemented control measures.

 

The risk for Legionnaires’ disease should be considered higher for persons above 40 years of age, smokers and immune-compromised persons. For this group, timely diagnosis and appropriate treatment will be particularly important.

 

 

As Legionnaires’ disease cannot be transmitted from human to human, the risk for the EU remains very limited apart from susceptible people visiting the affected areas.

 

The information given  to members of the public about their potential exposure is important to ensure timely diagnosis and appropriate treatment. This has been addressed by the Scottish authorities by  setting up a telephone hotline.

 

 

 

For a brief history of the discovery of Legionnaires disease you may wish to revisit my blog from last week called The Legionella Outbreak in South West Edinburgh. You’ll also find more information on Legionella on the NHS website:

 

Legionnaires' disease

Introduction

Legionnaires’ disease is a potentially fatal lung infection (pneumonia) that is caused by the legionella bacteria. Legionnaires’ disease is caught by breathing in small droplets of contaminated water. It is not contagious and cannot be spread directly from person to person.

 

Initial symptoms include a high fever and muscle pain. Once the bacteria begin to infect your lungs, you may also develop a persistent cough (see Legionnaires disease - symptoms). Prompt treatment using antibiotics is essential to reduce the risk of death. See Legionnaires’ disease - treatment for more information.

(Continue . . . )

Updating Edinburgh’s Legionnaires Outbreak

 

 

# 6372

 

 

Since yesterday, an additional 10 cases of Legionella have been identified in Edinburgh, Scotland bring the total to 61 in a week. It is considered likely that more people are affected, albeit mildly and are not seeking medical care.

 

While no environmental source has been identified, HVAC cooling towers (the most common point of origin) in the south western part of the city have been treated, and it is hoped that this will result in a drop in cases.

 

For more on the origins of this outbreak, and a brief history of Legionnaires diseases, you may wish to revisit (The Legionella Outbreak in South West Edinburgh).

 

You’ll also find a very instructive PDF file available from the ECDC website called:

 

Legionella Pneumonia Geographic Information System: a helpful tool in cluster detection

 

This presentation was made by Sjoerd M. Euser, PhD at the 2010 European Scientific Conference on Applied Infectious Disease Epidemiology (ESCAIDE) in Lisbon in 2010.

 

 

We’ve the latest statement from NHS Lothian, the public health authority in charge of the Edinburgh area.

 

 

Outbreak of Legionella in South West Edinburgh

Update - 07/06/2012 17:30

Legionnaires’ outbreak update - number of cases stands at 61

 

The latest reports from the Scottish Government Resilience Room (SGoRR) on the Edinburgh Legionnaires’ disease outbreak show that there are now 24 confirmed cases and 37 suspected cases.

 

As at 12pm today, of those cases being treated in hospital, 12 were in intensive care and 28 are on general wards.

 

A total of 13 cases are being treated in the community, five have been discharged from hospital and one person has sadly died.

 

Two cases are being treated outwith the NHS Lothian area – one in Highland and one in the north of England. Both of these cases are being treated as part of the south west Edinburgh outbreak and have connections to the area.

 

People that are being admitted to hospital with symptoms are now generally speaking in a better state of health than has previously been the case. The ages of those affected now ranges between 19 and 88, with more males than females affected.

 

As of yesterday, NHS 24 had received 48 calls to the dedicated helpline. However, there was a 20 per cent increase in the number of calls to their regular number about Legionnaire’s disease.

 

The investigation into the source of the outbreak is continuing, with all 16 cooling towers in the affected area now having been inspected.

 

Those cooling towers which were considered to possibly require re-treating are now undergoing this process.

 

Health Secretary Nicola Sturgeon said: “It is a positive sign that those people being admitted to hospital are, generally speaking, less ill than had been the case at the start of the outbreak and we are seeing an increase in the numbers of people well enough to be treated in the community.

 

“NHS Lothian services are busy but coping and I would like to pay tribute to NHS staff who are coping extremely well with this situation.

 

“It remains the case that the risk to the general public remains low but anyone with concerns should contact their GP or NHS 24’s dedicated hotline on 0800 0858 531.

 

“I want to stress that this bacteria is not passed on person to person or by drinking water.

 

“Investigations into the source of this outbreak, which are primarily led by the City of Edinburgh Council and the Health and Safety Executive and supported by Health Protection Scotland, are making good progress. I would hope that over the next few days this investigation will start to deliver answers about where the source of the outbreak might be. However, it is important to note that sometimes it is not possible to conclusively identify a source.

 

The Legionella Outbreak in South West Edinburgh

Legionella Bacteria - Photo Credit CDC PHIL

 

# 6370

 

There’s a rapidly spreading outbreak of Legionella in Scotland this week,  and I’ve details from the NHS and HSE. 

 

But first . . . a little background and history.

 

In July of 1976, while many of us in the health care field were waiting for the expected arrival of a swine flu pandemic (see Deja Flu, All Over Again), another medical crisis was brewing  at the Bellevue Stratford Hotel in Philadelphia.

 

This was the scene of the gathering of hundreds of veterans belonging to the American Legion, celebrating this country’s bicentennial.  Within a couple of days of their arrival, scores fell ill with a serious flu-like illness.

 

At first, many believed this was the first arrival of the expected flu pandemic, but soon it became evident that this was something else entirely.  But exactly what it was would take months to determine.

 

During this outbreak, 221 people were treated and 34 died.

 

But it wouldn’t be until early in 1977 that a definitive cause would be isolated by the CDC – a Gram negative, aerobic bacteria found growing in the hotel’s air-conditioning cooling tower – that provoked a serious form of pneumonia.

 

Dubbed `Legionnaire's Disease’ by the press, this bacterium was named Legionella, and the pneumonia it produces Legionellosis.

 

While `discovered’ in 1976 and identified the following year, Legionella had been with us, and causing serious illness, for a long time. It had caused earlier outbreaks, including one in Austin, Minnesota in 1957 (Osterholm et al., 1983) and at Saint Elizabeth’s Hospital in Washington, D.C. in 1965.  

 

The cause of these outbreaks wasn’t identified, however, until retrospective studies were conducted after the Philadelphia outbreak.  

 

We now know Legionella to be a major cause of infectious pneumonia, and that it sometimes sparks large outbreaks of illness.  According to the CDC between 8,000 and 18,000 Americans are hospitalized with Legionnaire's Disease each year, although the actual number of infected is likely higher.

 

All of which serves as prelude to the following report on the rising number of Legionella cases being diagnosed this week in Edinburgh Scotland.

 

As of today, the Associated Press is reporting 51 confirmed cases (link), one death, and more cases are expected to turn up.

 

So far, the source of this environmental pneumonia has not been identified.

 

 

Running point in the investigation is NHS Lothian, which is the public health authority for the Edinburgh area. 

 

The first press release on this outbreak came 4 days ago with the announcement of the first four cases. The next day there were six,  and the day after that . . . thirteen. 

 

Now the number stands at 51, and at least 10 more suspected cases are being tested.

 

You can read the progression of daily reports by the NHS at the link below, with the last update from yesterday.

 

Outbreak of Legionella in South West Edinburgh - Last updated 07/06/2012 AM

Update - 07/06/2012 AM

The Cabinet Secretary for Health & Wellbeing made a statement on the Legionella Outbreak at the Scottish Parliament this morning. You can watch it online at 

http://www.scottish.parliament.uk/newsandmediacentre/30912.aspx

---

Update - 06/06/2012

Resilience team report on outbreak latest

The latest reports from the Scottish Government Resilience Room (SGoRR) on the Edinburgh Legionnaires’ outbreak show that there are now 21 confirmed cases and 19 suspected cases.

 

One of the confirmed cases has died, two have been discharged from hospital and 12 are being treated in intensive care.

 

An emergency information leaflet will be delivered to all homes and businesses in affected areas tomorrow. GPs have also been provided with information on spotting the signs of infection.

 

A dedicated NHS helpline has been set up for anyone concerned and can be reached on 0800 0858 531.

 

Health Secretary Nicola Sturgeon said:

 

“The fact remains that the risk to the general public is low – however, due to the incubation period of the infection we are still expecting to see an increase in cases over the next couple of days.

(Continue . . . )

 

 

Obviously these numbers continue to rise, and press reports now differ from the numbers posted above.

 

The NHS maintains the following  website with more information on Legionella:

 

Legionnaires' disease

Introduction

Legionnaires’ disease is a potentially fatal lung infection (pneumonia) that is caused by the legionella bacteria. Legionnaires’ disease is caught by breathing in small droplets of contaminated water. It is not contagious and cannot be spread directly from person to person.

 

Initial symptoms include a high fever and muscle pain. Once the bacteria begin to infect your lungs, you may also develop a persistent cough (see Legionnaires disease - symptoms). Prompt treatment using antibiotics is essential to reduce the risk of death. See Legionnaires’ disease - treatment for more information.

(Continue . . . )

 

 

To put this in context, the largest outbreak of Legionnaires disease in recent years in the UK occurred a decade ago, in the town center of Barrow-in-Furness, Cumbria which ultimately produced 180 known infections, and 7 deaths.

 

The following 62-page report on that outbreak is available on the HSE website:

 

Report of the public meetings into the legionella outbreak in Barrow-in-Furness, August 2002

 

While doctors struggle to treat those infected, disease detectives in Scotland are working to find the environmental source of this virulent bacteria, in order to stop the outbreak.

 

I’ll update this story when new details emerge.

Study: Wiper Fluid And Legionella

 

 

 

# 4645

 

 

In July of 1976, while many of us in the health care field were waiting for the expected arrival of a swine flu pandemic (see Deja Flu, All Over Again), another medical crisis was brewing  at the Bellevue Stratford Hotel in Philadelphia.

 

This was the scene of the gathering of hundreds of veterans belonging to the American Legion, celebrating this country’s bicentennial.  Within a couple of days of their arrival, scores fell ill with a serious flu-like illness.

 

At first, many believed this was the first arrival of the expected flu pandemic, but soon it became evident that this was something else entirely.  But exactly what it was would take months to determine.

 

During this outbreak, 221 people were treated and 34 died. 

 

It wouldn’t be until early in 1977 that a definitive cause would be isolated by the CDC – a Gram negative, aerobic bacteria found growing in the hotel’s air-conditioning cooling tower – that provoked a serious form of pneumonia.

 

Dubbed `Legionnaire's Disease’ by the press, this bacterium was named Legionella, and the pneumonia it produces Legionellosis.

 

While `discovered’ in 1976, Legionella had been with us, and causing serious illness, for a long time.  It had caused earlier outbreaks, including one in Austin, Minnesota in 1957 (Osterholm et al., 1983) and at Saint Elizabeth’s Hospital in Washington, D.C. in 1965.  

 

The cause of these outbreaks wasn’t identified, however, until retrospective studies were conducted after the Philadelphia outbreak.  

 

We now know Legionella to be a major cause of infectious pneumonia, and that it sometimes sparks large outbreaks of illness.  According to the CDC between 8,000 and 18,000 Americans are hospitalized with Legionnaire's Disease each year.

 

For more information on the disease, the CDC maintains a fact sheet at Patient Facts: Learn More about Legionnaires' disease.

 

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.  

 

Yesterday we learned of a rather unique potential delivery system for Legionella – the windshield washer of your car.

This from the UK’s Health Protection Agency website.

 

Legionnaires’ disease

14 June 2010

A preliminary HPA study, published in the European Journal of Epidemiology, has found an association between not using screen wash in wiper fluid and the risk of contracting Legionnaires' disease.

More information:

 

Legionnaires' disease, caused by the legionella bacteria, is commonly linked to water systems such as air conditioning units, showers and fountains, where water is given off in a fine spray.

 

The case control study looked into the potential risk factors for drivers and passengers, given that most cases of sporadic, or isolated, Legionnaires' disease are rarely traced to a source, and that drivers figure disproportionately among cases of sporadic Legionella infection.

 

Researchers for the study interviewed 75 patients in England and Wales who had recovered from community acquired Legionnaires' disease between July 2008 and March 2009, comparing them to a group of matched people who had not experienced any similar infection.

 

The study found two exposures associated with vehicle use where there was an increased risk of Legionnaires' disease: driving through industrial areas and driving or being a passenger in a vehicle without screenwash in its wiper fluid. These associations had not been previously identified.

 

Further studies are now required to further explore this finding, and to determine whether the use of screen wash in wiper fluid could play a role in preventing this disease. The HPA is exploring ways of taking this forward with partner organisations.

 

 

You can read the study at: Windscreen wiper fluid without added screenwash in motor vehicles: a newly identified risk factor for Legionnaires' disease The European Journal of Epidemiology, 8 June 2010

 

Plain water in the wiper reservoir, kept warm and dark under the hood near the engine, is apparently conducive to the growth of Legionella.  It can become aerosolized when you clean your windshield, and subsequently inhaled.

At least, that’s the operating theory of this paper.

 

`Screenwash’ is generally called `wiper fluid’ here in the US, and usually contains some form of antifreeze or alcohol. Those additives, investigators believe, are enough to inhibit the growth of this bacterium.

 

 

While more study is needed to pin down just how prevalent this mode of transmission really is (the authors suggest up to 20% of sporadic cases of Legionnaire's in the UK), this is a fascinating bit of detective work.

 

The Pump Handle  posted more on this story last night in Legionnaires' Disease Linked with Wiper Fluid, including asking why – since this information has been known for months – it wasn’t announced sooner.