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Yellowstone National Park Superintendent Suzanne Lewis announced today that a recent study done at the request of the National Park Service shows that some thermal waters in the park, including the popular soaking spot Boiling River, contain the thermophilic amoeba, Naegleria fowleri and the bacterium Legionella.
Naegleria fowleri is a single-celled organism that is found worldwide in soil and all natural surface waters, particularly very warm and shallow waters. Naegleria fowleri is known to cause primary amoebic
meningoenchephalitis (PAM). PAM is an extremely rare disease that causes inflammation of the lining of the brain and spinal cord and can often be fatal. The disease can occur when water containing the organism gets into the nose and then moves up the nasal passages to the brain. Despite the common occurrence of Naegleria fowleri in Yellowstone, there is no indication in the park's history that anyone has died from exposure to this organism while soaking in the park's thermal waters.
The Legionella bacterium, found in many types of natural and human-built water systems nationwide, is capable of causing disease in humans, especially Legionnaires' disease. As with PAM, the National Park Service has no evidence of confirmed exposure in Yellowstone National Park.
There are inherent risks associated with many activities in Yellowstone National Park, including swimming or soaking in thermal areas. Park visitors planning to swim or soak in the park's thermal waters do so at their own risk. To reduce the risk of exposure, do not expose your head to the water by any means (for example, immersion, splashing, diving, or touching your face). If you have any signs or symptoms of irritation or disease, seek medical attention immediately.
Boiling River, located between Mammoth Hot Springs and Gardiner, Montana, is a well-known swimming area where water from the hot springs enters the Gardner River. Boiling River has been closed recently due to high water activity but reopened this morning (July 3, 2003) to the public with appropriate public advisories. Park visitors are allowed to soak along the bank of the Gardner River where the hot springs water warms and mixes with the river's water. Swimming or bathing is prohibited in thermal pools or
streams where water flows entirely from a thermal spring or pool.
Additional information on Naegleria fowleri and Legionella:
July 03, 2003
A recent research study ( Survey of Naegleria: Yellowstone National Park 2001-2002 , by Kathy B. Sheehan, Jennifer A. Fagg, and Joan M. Hensen of Montana State University, Bozeman) surveyed areas in Yellowstone National Park where visitors soak in thermal waters - either legally or illegally for potential amoebic pathogens that pose a disease risk to humans. The study was done at the request of and funded by the National Park Service.
Study results show that the thermophilic amoeba, Naegleria fowleri and the bacterium Legionella , were identified at some sites in the Yellowstone National Park?including Boiling River, a popular swimming area inside the park between Gardiner, Montana, and Mammoth Hot Springs, Wyoming.
Many thousands of park visitors and staff have soaked in Yellowstone's thermal waters throughout the park's history (it's estimated that more than 28,000 people use Boiling River alone each year). There is no indication, however, that anyone has become seriously ill or died from exposure to either of these pathogens while swimming in thermal features in the park.
There are inherent risks associated with many activities in Yellowstone National Park, including swimming in thermal waters. The following questions and answers are intended to help park visitors and staff assess the risks associated with swimming in thermal waters so that they can make an informed choice as to whether they wish to participate in this activity while in the park.
What is Naegleria? Naegleria is an amoeba that is commonly found in soils and warm bodies of water throughout the world, such as thermal waters. Only the species, Naegleria fowleri, has been found to infect humans and other mammals.
What is Naegleria fowleri? Naegleria fowleri is an amoeba that causes primary amoebic meningoenchephalitis (PAM), a very rare but often fatal infection of the human nervous system.
How do you get PAM? Infection occurs when water containing the amoeba Naegleria fowleri invades the nasal passages. Once water containing the amoeba is ingested through the mouth or nose, it moves up the nasal passages to the brain and/or spinal cord where it multiplies and symptoms worsen. Infection usually results in death within 7-10 days.
Is there treatment for PAM? Yes, but most cases are fatal if not diagnosed and treated immediately. Once clinical symptoms begin, there is a very short time during which therapy might be effective.
What are the symptoms of PAM? Symptoms include headache, fever, nausea and vomiting, stiff neck, confusion, loss of balance and bodily control, seizures, and coma as symptoms worsen.
Where is Naegleria fowleri present in Yellowstone National Park? Naegleria fowleri has been identified in several locations, including Boiling River. The amoeba has been confirmed at Nymph Creek, Hillside Springs, Seismic Geyser, Mallard Lake Trail, Madison Campground, Terrace Springs, and Bathtub Spring. However, soakers should be aware that not all springs were surveyed and all thermal waters should be considered suspect.
How can I protect myself from getting an infection with Naegleria fowleri? There is no guarantee of your safety if you bathe in thermal waters in Yellowstone National Park. To reduce your risk, do not expose your head to the water by any means (for example, immersion, splashing, diving, or touching your face). If you have any signs or symptoms of irritation or disease, seek medical attention immediately.
What is Legionella? The Legionella bacterium is a species found in many types of natural and human-built water systems that is capable of causing disease in humans. Legionellosis is an infection caused by the bacterium Legionellapneumophila , which is an aquatic organism that thrives in warm environments and has been shown to cause Legionnaires' disease (pneumonia). A less severe form of the species causes Pontiac fever, which is an acute-onset, flu-like, non-pneumonic illness.
How is the Legionellosis transmitted? In the built-environment, by breathing mists that come from a water source, such as evaporative air coolers that are contaminated with Legionella bacteria. Means of transmission in natural landscapes is poorly understood. Person-to-person transmission does not occur.
Who is at risk of getting an infection from the Legionella bacterium? People of any age may get Legionellosis, but t he elderly, cigarette smokers, persons with chronic lung or immunocompromising disease, and persons receiving immunosuppressive drugs are more at risk.
How fatal is Legionnaires' disease or Pontiac fever? An estimated 8,000 to 18,000 people get Legionnaires' disease in the United States each year. Death occurs in 5-15 percent of those cases. Pontiac fever is a self-limited disease that requires no treatment.
What is the park doing to address this problem? First, we have no information that indicates that there is a problem at this time. There have been no documented cases of park visitors or staff becoming seriously ill or dying from PAM or Legionellosis after exposure to the park's thermal waters.
Yellowstone requested and funded the current study to obtain information on how widespread Naegleria is in the park, especially areas where soaking occurs. The researchers found Legionella?the first report of the species in the park? as an adjunct to the principle goal of the study.
The park desires to conduct further research, including air and mist sampling, and work with other subject experts regarding how best to address this issue.
Information provided by the NPS
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