Update 10.10.16

UW Medical Center (UWMC) has not detected any additional Legionella cases. To-date, water samples taken from the in-patient unit in Cascade Tower have tested negative for Legionella bacteria since UWMC completed the hyperchlorination process on September 20. Two scrub sinks in the operating room showed a very low level of Legionella bacteria; those two sinks have been taken out of service.  In the Cascade Tower, UWMC continues to use filters  in the sinks and showers and has added supplemental chlorine to the hot water system to protect against Legionella.  They continue to work with our communicable disease investigation team to conduct ongoing checks for Legionella bacteria and to implement ongoing Legionella prevention measures.

Update  (9.27.16)

Based on further investigation, the most recent case of Legionella at the UW Medical Center (UWMC) is believed to have been exposed to the bacteria either in the community or during an earlier hospitalization before water restrictions and Legionella precautions were implemented at the UWMC.

The case was admitted to UWMC after Legionella precautions were put in place and had clinically apparent onset of symptoms suggestive of Legionella infection on September 18^th (not September 23^rd, as previously reported), two days after hospital admission. This means the majority of the exposure period was prior to the recent hospitalization and all of the exposure period was prior to when UWMC hyper-chlorinated the water system as part of their Legionella control measures on September 19-20.

As was previously reported, the potable (drinkable) water system at the UWMC Cascade Tower building is thought to be the source of this outbreak. Multiple environmental samples from the water system at the building have been positive for Legionella bacteria, including Legionella pneumophila, the cause of pneumonia in the current cases.

Heater-cooler devices are often necessary during surgeries to warm or cool patients as part of their care. Part of our investigation focused on whether these units could have contributed to the spread of Legionella infection at UWMC because water and swabs from three of these units initially were found to have Legionella growth when tested. Subsequently, all the heater-cooler units showed presence of Legionella species. However, the heater-cooler units are not thought to be the source of the infections for a number of reasons.

• Not all the cases had exposure to a heater cooler unit: only two of the five cases had surgical procedures in which heater-cooler devices were used. UWMC performs about 50 operations a month using the heater-cooler units.
• One type of heater-cooler unit, the Sorin 3T, has been confirmed in other hospitals in Europe and elsewhere in the United States (but not locally) as a source of infections with another type of bacteria called nontuberculosis mycobacteria (NTM). These were not lung infections, and to-date there have been no confirmed reports of Legionella transmission from this or any other heater-cooler model.
• Among the five identified Legionella cases at the UW to date, all were cared for in the Cascade Tower, where Legionella was recovered from water samples.
• Since Legionella was detected in the UWMC Cascade Tower plumbing, ice machines and faucets, recovery of Legionella from heater-cooler units, which were filled with tap water and ice, is not surprising.
• Patients are on breathing machines (ventilators) during surgery and their air supply is protected and separate from the rest of the operating room air (where the heater-cooler units are).
• The water in the heater-cooler units does not come into contact with the patient or the patient’s blood at any time.
• The timing of the onset of Legionella infection in the two patients that did have surgery in which heater-cooler units were used was outside of the typical incubation period for Legionella in one case and at the end of that period in the other.

Although the heater-cooler units are not likely to have been related to transmission of Legionella at UWMC, steps have been taken at UWMC to eliminate the potential risk from Legionella growth in these machines.

Update (9.26.16)

The University of Washington Medical Center (UWMC) has notified Public Health – Seattle & King County of a fifth patient who has tested positive for Legionella. The patient is a woman in her fifties who is not a resident of Washington State. She remains hospitalized and is currently in satisfactory condition. The patient developed symptoms of Legionella on 9/23/16 and tested positive for Legionella pneumophila serogroup 1 on 9/25/16. The case was reported to Public Health on 9/26.

This patient was hospitalized in the UWMC’s Cascade Tower before the Legionella outbreak was recognized and precautions were put in place at UWMC. She was discharged before the identification of the outbreak and then readmitted almost two weeks later, after the precautions were in place. Her symptoms of Legionella infection developed after her readmission.

We can’t say with certainty when or where the infection was acquired. The typical incubation period for Legionnaires disease is 2-10 days but incubation periods longer than 10 days have been reported in other outbreaks, particularly among immunocompromised patients.

Update (9.24.16)

It has been 11 days since UWMC implemented corrective actions and enhanced precautions to protect patients from Legionella and no cases have occurred. Cases of Legionella typically occur 2-10 days after exposure to the bacteria. Although it is possible additional cases will be identified, the absence of new cases suggests that the steps taken by UWMC to eliminate Legionella transmission are working.

Although the investigation is active and ongoing and additional results are pending, available evidence currently points to the water system in the Cascade Tower building as the most likely source of the outbreak.

Hospital-acquired Legionnaires’ disease has been reported from many hospitals since the first outbreak in 1976. Although cooling towers were linked to the cases of Legionnaires’ disease in the years after its discovery, drinkable water has been the environmental source for almost all reported hospital outbreaks. Infection is acquired when patients inhale small droplets of water that are contaminated with Legionella, for example when drinking, consuming ice chips, showering, or using water in sinks.

Heater-cooler devices are often necessary during surgeries to warm or cool patients as part of their care. Part of our investigation focused on whether these units could have contributed to the spread of Legionella infection at UWMC because water and swabs from several of these units were found to have Legionella growth when tested. At this time, we do not believe the heater-cooler units are linked to Legionella transmission for a number of reasons:

• Not all the cases had exposure to a heater cooler unit: Only two of the four cases had surgical procedures in which heater-cooler devices were used.
• One type of heater-cooler unit, the Sorin 3T, has been confirmed in other hospitals in Europe and elsewhere in the United States (but not locally) as a source of infections with another type of bacteria called nontuberculosis mycobacteria (NTM). These were not lung infections, and to-date there have been no confirmed reports of Legionella transmission from this or any other heater-cooler model.
• Among the four identified Legionella cases at the UW to date, all were cared for in parts of the hospital where Legionella was recovered from water samples.
• Since Legionella was detected in the UWMC Cascade Tower plumbing ice machines and faucets, recovery of Legionella from heater cooler units, which were filled with tap water and ice, is not surprising.
• Patients are on breathing machines (ventilators) during surgery and their air supply is protected and separate from the rest of the operating room air (where the heater cooler units are).
• The timing of the onset of Legionella infection in the two patients that did have surgery in which heater cooler units were used was well outside of the typical incubation period for Legionella in one case and at the end of that period in the other.

Although we do not believe the heater-cooler units are involved in transmission of Legionella at UWMC, steps have been taken at UWMC to eliminate the potential risk of Legionella growth in these machines.

Update (9.16.16)

UWMC informed us yesterday that a fourth patient has been diagnosed with Legionella pneumophilia and the patient is currently in satisfactory condition. This patient was also hospitalized in the Cascade Tower where environmental tests have found Legionella; the patient’s exposure would have been prior to the identification of the bacteria, before protective measures were put in place. This patient is a male in his forties who was at increased risk for infection due to an underlying medical condition. He is not a resident of Washington state.

UWMC has posted additional updated information.

Update (9.14.16)

UWMC informed us yesterday that another patient in their cardiac care unit died. This patient had pneumonia, and Legionella may have been a contributing factor. The exact cause of death has not yet been determined. The death happened on August 27, but the connection with Legionella was made at autopsy.

UWMC also informed us that environmental samples of their water supply in the Cascade Tower, which includes their cardiac care unit, tested positive for Legionella. They have taken immediate steps to reduce the risk where Legionella has been found in the water.

Public Health’s role has been to assist with the assessment of the extent of the problem, help identify the source of Legionella, continue to monitor for new cases in collaboration with UWMC, and provide recommendations on control measures to reduce ongoing risk. In this capacity, we have been consulting with our partners at CDC.

We can’t predict if additional cases will be identified at UWMC, but it is possible because of exposures that happened at the hospital before the Legionella was identified and protective actions were put into place.

However, for most people, the risk of Legionella is very low. All three patients who developed Legionnaire’s disease were at high risk for this infection (see the high risk factors listed in the original post below).

Update (9.9.16)

The University of Washington Medical Center has informed Public Health – Seattle & King County that one patient who was hospitalized with Legionella infection died last night. Legionella is believed to be a contributing factor in the death.

Original post (9.8.16)

The University of Washington Medical Center (UWMC) has notified Public Health – Seattle & King County of two patients who were diagnosed with a serious type of pneumonia called Legionnaires’ disease caused by infection from Legionella bacteria.  Both patients received care in their cardiac care units.

The first patient was previously reported on August 26, 2016, and the patient’s history suggested that exposure to Legionella might have been at the hospital or in the community before the patient’s hospital stay. The second patient was reported on September 6, 2016, and this patient was at UWMC during the entire exposure period. One patient remains hospitalized and is receiving treatment for the Legionella  infection.  The other patient has been discharged from the hospital and is at home.

At this time there is no evidence to suggest risk to the public or patients outside of the units where these two patients were cared for at UWMC.

Public Health is in the very early phase of our investigation. We are working closely with UWMC to determine if other patients may have been infected, to identify a potential source of the infections, and to address any ongoing risk. UWMC is also working with an environmental assessment specialist to investigate the source of Legionella bacteria. At this time, no additional cases of Legionella have been identified at UWMC.

UWMC is cooperating fully with this investigation and is taking appropriate steps to protect patient and staff safety, and to assure that patients with pneumonia get appropriate laboratory testing.

What is Legionella?

Legionella is a type of bacterium found naturally in freshwater environments, like lakes and streams, and grows best in warm water. It can become a health concern when it grows and spreads in human-made water systems like hot tubs, hot water tanks and heaters, decorative fountains, cooling towers (such as those used in air conditioning systems), and large plumbing systems.

People can become infected with Legionella when they breathe in a mist that is contaminated with the bacteria. A Legionella infection can turn into illness affecting the lungs, and in some cases, it can cause Legionnaires’ disease.

Legionnaire’s disease is serious, but it can be treated with antibiotics. Most people who get sick need care in a hospital but make a full recovery. However, about 1 out of 10 people who get Legionnaires’ disease will die from the infection.

Who is at higher risk of getting sick?

Most healthy people do not get sick after being exposed to Legionella. People at increased risk of getting sick are:

• People 50 years or older
• Current or former smokers
• People with a chronic lung disease (like chronic obstructive pulmonary disease or emphysema)
• People with a weak immune system from diseases like cancer, diabetes, or kidney failure
• People who take medications that suppress (weaken) the immune system (like after a transplant operation or chemotherapy)

Public Health – Seattle & King County’s role in the investigation

Investigation of infectious diseases is part of the essential work of Public Health – Seattle & King County. In this incident, our role is to assist with the investigation and assessment of the extent of the problem, identification of a source of the legionella, and eliminate ongoing risk at the healthcare facility. We also provide information to the public about Legionnaire’s disease and on the findings and status of our investigation.

Learn more on Legionella from the CDC.