1. The Danger in Your Swimming Hole
Naegleria Fowleri:
The Danger in Your Swimming Hole
Nancy Wilson, MPH student
Walden University
PUBH , Environmental Health
Dr. Raymond Thron
Summer 2014
Welcome. Today we are going to be discussing Naegleria fowleri, known as the brain-eating amoeba that often infects children who have been swimming or playing in warm fresh water. This is an especially relevant topic in the summer, as both air and water temperatures heat up and make this amoeba a real threat. I hope this presentation will prove useful to all parents who are looking for ways to protect their children from this stealthy killer.

2. Learning Objectives What is Naegleria fowleri?
What is primary amebic meningoencephalitis?
How is a person infected?
How can infection be prevented?
My intention is that by the conclusion of this presentation, you will understand what exactly Naegleria fowleri and its associated disease, primary amebic meningoencephalitis, are, how a person is infected, and how infection can be prevented. This is a rare disease, and my hope is that providing education and increasing awareness will result in fewer infections and deaths.

3. What is Naegleria fowleri?
Thermophilic, free-living ameba
Found in warm fresh water
Lakes, ponds, rivers, hot springs
Feeds on bacteria
Naegleria fowleri is a thermophilic, free-living ameba, which is to say that it is a single-celled microbe that loves heat. It is therefore only found in warm bodies of water. It begins to multiply when ambient temperatures are over 30 degrees Celsius, and it can tolerate temperatures up to 45 degrees Celsius. It is never found in oceans because it feeds on bacteria in fresh water. It is only infectious to humans during the trophozoite stage of its life cycle, which is pictured on the slide before you.
Image credit: Centers for Disease Control and Prevention. (2013). Naegleria fowleri – Primary Amebic Meningoencephalitis (PAM). Retrieved from
Kemble, S. K., Lynfield, R., DeVries, A. S., Drehner, D. M., Pomputius III, W. F., Beach, M. J.,...Danila, R. (2012). Fatal Naegleria fowleri infection acquired in Minnesota: Possible expanded range of a deadly thermophilic organism. Clinical Infectious Diseases, 54(6), doi: /cid/cir961

4. How are people infected?
A person becomes infected when N. fowleri enters the nasal passage and then travels via the olfactory nerves to the brain. Infection does not occur by swallowing contaminated water, and the infection cannot be transmitted from one person to another.
Centers for Disease Control and Prevention. (2013). Naegleria fowleri – Primary Amebic Meningoencephalitis (PAM). Retrieved from

5. Where can N. fowleri be found?
Every continent except Antarctica (Painter, Pfau, Brady, & McFarland, 2013)
In the U.S., more frequently in southern states (Yoder et al., 2012)
In ponds, lakes, rivers, and hot springs (Painter et al., 2013)
In drinking water
Not regulated (Yoder et al., 2012).
N. fowleri has been found on every continent, except the icy expanse of Antarctica. This widespread distribution is likely attributable to the ameba's ability to tolerate a range of physical conditions, including variations in temperature, pH, and dissolved oxygen. As previously mentioned, the ameba most favors warm water, so it is probably unsurprising to note that in the U.S. it is found most frequently in southern states. The ameba is found in fresh bodies of water, and it is also found in some drinking water supplies. N. fowleri is currently not one of the contaminants that is under national drinking water regulation by the EPA, though it is on the list of contaminant candidates.
Painter, S. M., Pfau, R. S., Brady, J. A., & McFarland, A. S. (2013). Quantitative assessment of Naegleria fowleri and Escherichia coli concentrations within a Texas reservoir. Journal of Water & Health, 11(2), doi: /wh
Yoder, J. S., Straif-Bourgeois, S., Roy, S. L., Moore, T. A., Visvesvara, G. S., Ratard, R. C.,... Xiao, L. (2012). Primary amebic meningoencephalitis deaths associated with sinus irrigation using contaminated tap water. Clinical Infectious Diseases, 55(9), e79-e85.

6. Reported U.S. Cases,
There have been 132 cases reported between 1962 and 2013 in the United States. This map allows us to visualize a couple of things. First, you may note that there have been reported cases as far north as Minnesota. Second, we see that the concentration of cases is in the bottom half of the United States. This distribution makes sense because the southern region is where temperatures are consistently higher and where bodies of water are more likely to stay at warmer temperatures. While only 0 to 8 cases of infection occur each year in the U.S., more cases do appear in years when heat waves lead to higher water and air temperatures.
Centers for Disease Control and Prevention. (2013). Naegleria fowleri – Primary Amebic Meningoencephalitis (PAM). Retrieved from

7. Why should we pay attention?
Naegleria fowleri causes primary amebic meningoencephalitis, or PAM, which is a rare infection that is almost uniformly fatal. There have only been about 440 cases identified worldwide, but there is a 98% fatality rate. Of the 132 U.S. cases since 1962, only 3 have survived.
Sood, A. A., Chauhan, S. S., Chandel, L. L., & Jaryal, S. C. (2014). Prompt diagnosis and extraordinary survival from Naegleria fowleri meningitis: A rare case report. Indian Journal of Medical Microbiology, 32(2), doi: /

8. What is PAM? Primary Amebic Meningoencephalitis
membranes + brain + inflammation
Primary amebic encephalitis is a medical condition that combines meningitis, which is inflammation of the membranes of the central nervous system, and encephalitis, which is inflammation of the brain.
Centers for Disease Control and Prevention. (2013). Naegleria fowleri – Primary Amebic Meningoencephalitis (PAM). Retrieved from

9. The Symptoms of PAM Headache Fever Nausea/vomiting Stiff neck
Altered mental status
Seizures
Yousuf, F. A., Siddiqui, R., Subhani, F., & Khan, N. A. (2013). Status of free-living amoebae (Acanthamoeba spp., Naegleria fowleri, Balamuthia mandrillaris) in drinking water supplies in Karachi, Pakistan. Journal of Water & Health, 11(2), doi: /wh
It may be difficult to immediately diagnose PAM because the symptoms are similar to that of bacterial meningitis. Initial symptoms may include severe frontal headache, fever, nausea, or vomiting. As the infection progresses, symptoms may include a stiff neck, altered mental status, seizures, or hallucinations. Often a victim will go into a coma that concludes with death. Because the disease progresses very quickly and can be difficult to recognize, diagnosis sometimes does not occur until after death.
Centers for Disease Control and Prevention. (2013). Naegleria fowleri – Primary Amebic Meningoencephalitis (PAM). Retrieved from

10. How quickly does PAM progress?
Symptoms start 1-7 days after infection (median is 5 days)
Death occurs an average of 10 days after infection, or 1-12 days (median 5.3 days) after initial symptoms
The onset of symptoms can differ with each person, and initial symptoms can be mild enough that they are overlooked. Symptoms usually start about 5 days after infection, and death usually follows about 5 days after the start of symptoms.
Centers for Disease Control and Prevention. (2013). Naegleria fowleri – Primary Amebic Meningoencephalitis (PAM). Retrieved from
Painter, S. M., Pfau, R. S., Brady, J. A., & McFarland, A. S. (2013). Quantitative assessment of Naegleria fowleri and Escherichia coli concentrations within a Texas reservoir. Journal of Water & Health, 11(2), doi: /wh

11. Who is at risk? Children and young adults Males Freshwater swimmers
Those who play, swim, or bathe in fresh water in July or August
In the U.S., infections have occurred in all age groups, but 84% of cases have occurred in children under age 18. Over 75% have occurred in males. These groups are more likely to engage in diving, underwater swimming, water skiing and knee-boarding, and head dunking, and are therefore more likely to have water travel into the nose. Typically, infections are most likely to occur in July and August because that is when temperatures are hottest and water levels are lowest.
Centers for Disease Control and Prevention. (2013). Naegleria fowleri – Primary Amebic Meningoencephalitis (PAM). Retrieved from

12. Are people only at risk when swimming?
Short answer: No.
Nasal exposure to infected drinking water
Shower or bath
Slip-n-slide
Nasal irrigation or rinsing
The vast majority of infections in the U.S. have occurred after swimming or playing in a body of water, but there have been 6 infections that have been associated with water from drinking water systems. As mentioned previously, infections do not occur when this water is swallowed. Infections always occur when water goes up the nose. Therefore, in these cases the contaminated water was introduced nasally when the head was immersed while bathing, when playing on a slip-n-slide, or when performing nasal irrigation or rinsing.
Centers for Disease Control and Prevention. (2013). Naegleria fowleri – Primary Amebic Meningoencephalitis (PAM). Retrieved from

13. How is PAM diagnosed? Laboratory tests Direct visualization
Antigen detection
Polymerase chain reaction (PCR)
Ameba culture
Environmental detection
To receive a confirmed PAM diagnosis, it is necessary to use specific laboratory tests, which are currently only available in a few labs in the U.S. Sometimes amoebae can be seen using direct visualization of cerebrospinal fluid (CSF) under a microscope. Amebic antigens can be detected in tissue using chemical stains or with the use of special lights. The PCR method amplifies DNA from the amoebae in CSF to see if the amoebae are present. The amoebae can be grown on a culture, with further testing using PCR or direct visualization necessary to identify if the ameba present is N. fowleri. The last option is environmental detection, where water samples, rather than human samples, are tested. PAM is rare, and early detection is difficult, so about 75% of cases are currently diagnosed after death.
Centers for Disease Control and Prevention. (2013). Naegleria fowleri – Primary Amebic Meningoencephalitis (PAM). Retrieved from

14. What treatment is available?
Miltefosine, breast cancer drug
Successful usage in 2013 (CDC, 2013)
Amphotericin B, confirmed clinical efficacy
In combination with fluconazole, rifampicin, sulfadiazine, dexamethasone, or other drugs (Sood, Chauhan, Chandel, & Jaryal, 2014)
Early treatment is best!
Of the 3 PAM survivors in the U.S., 2 were diagnosed and treated in Both were successfully treated with Miltefosine, which is an investigational breast cancer drug also used to treat the parasitic disease leishmaniasis. Amphotericin B is the only drug with established clinical efficacy for PAM. It has been used to successfully treat cases in other countries. Frequently it is used in various combinations with other drugs, some of which are mentioned on the slide before you. The most important thing is to start treatment as early as possible. In the first 2013 case, the child was started on treatment within 36 hours of initial symptoms, and she made a full recovery. In the second case, the child was not treated until several days after initial symptoms, and although he survived, he likely has permanent brain damage.
Centers for Disease Control and Prevention. (2013). Naegleria fowleri – Primary Amebic Meningoencephalitis (PAM). Retrieved from
Sood, A. A., Chauhan, S. S., Chandel, L. L., & Jaryal, S. C. (2014). Prompt diagnosis and extraordinary survival from Naegleria fowleri meningitis: A rare case report. Indian Journal of Medical Microbiology, 32(2), doi: /

15. How can infection be prevented?
Avoid activities in freshwater when there is a high water temperature (Yoder et all., 2012)
Avoid getting water up the nose
Use nose clips (Yoder et al., 2012)
Avoid head submersion (CDC, 2013)
Avoid stirring up sediment during water- related activities (Yoder et al., 2012)
It is clear that early diagnosis and treatment can be difficult, so it is critical to take any available steps to prevent infection in the first place. Since most infections take place in warm fresh water, it would be most effective to avoid fresh water when the water temperature is high. If the water is too tempting, then the next preventative step would be to avoid getting water up the nose. It is effective to avoid putting your head underwater, but it would also be beneficial to wear a nose clip, so that even if water is splashed at you, it will be more difficult for it to enter your nose. Nose clips are essential during water activities, such as water skiing or knee-boarding, where the act of falling into the water makes it difficult to prevent water going up into the nose. It is also important to try not to stir up sediment in the water since that can increase the risk of ameba infection.
Centers for Disease Control and Prevention. (2013). Naegleria fowleri – Primary Amebic Meningoencephalitis (PAM). Retrieved from
Yoder, J. S., Straif-Bourgeois, S., Roy, S. L., Moore, T. A., Visvesvara, G. S., Ratard, R. C.,... Xiao, L. (2012). Primary amebic meningoencephalitis deaths associated with sinus irrigation using contaminated tap water. Clinical Infectious Diseases, 55(9), e79-e85.

16. How can infection be prevented?
Use sterile, distilled, filtered, or previously boiled water for nasal irrigation (Yoder et al., 2012)
Do not allow bathing water to go up in nose (CDC, 2013)
Avoid the use of slip-n-slides (CDC, 2013)
Do not allow children to play unsupervised with hoses or sprinklers (CDC, 2013)
Since drinking water systems can also be infected, it is important to take precautions at home as well. Water should be sterilized, distilled, filtered, or boiled before being used for nasal irrigation. You should avoid putting your head under water in the bath and avoid water near your nose in the shower. The use of slip-n-slides should be avoided, or at the very least a nose clip should be used. Children should not play unsupervised with hoses or sprinklers since they may accidentally squirt water in their noses.
Centers for Disease Control and Prevention. (2013). Naegleria fowleri – Primary Amebic Meningoencephalitis (PAM). Retrieved from
Yoder, J. S., Straif-Bourgeois, S., Roy, S. L., Moore, T. A., Visvesvara, G. S., Ratard, R. C.,... Xiao, L. (2012). Primary amebic meningoencephalitis deaths associated with sinus irrigation using contaminated tap water. Clinical Infectious Diseases, 55(9), e79-e85.

17. What should I do if I suspect Naegleria fowleri infection?
Go to the hospital immediately and report possible exposure
CDC Emergency Operations Center is available for consult on any suspected infection case
It is very important to avoid infection and to receive immediate treatment if infected. Therefore, if you or someone you know have had exposure to warm freshwater and begin feeling ill, it is crucial to immediately seek medical attention at the nearest hospital. Basic medical clinics and primary care physicians are unlikely to have access to necessary diagnostic equipment or treatment medications, so reporting to a full-service medical facility as soon as possible is ideal. Your physician can contact the CDC Emergency Operations Center for recommendations or consultation regarding diagnosis or treatment.
Centers for Disease Control and Prevention. (2013). Naegleria fowleri – Primary Amebic Meningoencephalitis (PAM). Retrieved from

18. Points to Remember Be wary of warm freshwater! Protect your nose!
It is better to be safe than sorry!
Early is best!
Hopefully you now have a solid understanding of both Naegleria fowleri and primary amebic meningoencephalitis. In summary, it is important to be cautious about any water-related activities in warm freshwater, particularly during the months of July and August. If you do engage in water activities, make sure to protect your nasal passages by avoiding head submersion and wearing nose clips. It is better to be cautious and wear nose clips than to be infected with a highly fatal disease. If you think there is even a possibility of infection, it is important to seek immediate medical attention. It is better to have a false alarm than to delay medical care until it is too late. The best chance for complete recovery is receiving treatment as soon as possible after infection.

19. References
Centers for Disease Control and Prevention. (2013). Naegleria fowleri – Primary Amebic Meningoencephalitis (PAM). Retrieved from
Kemble, S. K., Lynfield, R., DeVries, A. S., Drehner, D. M., Pomputius III, W. F., Beach, M. J.,...Danila, R. (2012). Fatal Naegleria fowleri infection acquired in Minnesota: Possible expanded range of a deadly thermophilic organism. Clinical Infectious Diseases, 54(6), doi: /cid/cir961
Painter, S. M., Pfau, R. S., Brady, J. A., & McFarland, A. S. (2013). Quantitative assessment of Naegleria fowleri and Escherichia coli concentrations within a Texas reservoir. Journal of Water & Health, 11(2), doi: /wh
There is not a lot of information about N. fowleri in the public forum, so if you would like to read more about it, I encourage you to use the CDC as a resource. The information the CDC website provides is thorough and easy to understand.

20. References
Sood, A. A., Chauhan, S. S., Chandel, L. L., & Jaryal, S. C. (2014). Prompt diagnosis and extraordinary survival from Naegleria fowleri meningitis: A rare case report. Indian Journal of Medical Microbiology, 32(2), doi: /
Yoder, J. S., Straif-Bourgeois, S., Roy, S. L., Moore, T. A., Visvesvara, G. S., Ratard, R. C.,... Xiao, L. (2012). Primary amebic meningoencephalitis deaths associated with sinus irrigation using contaminated tap water. Clinical Infectious Diseases, 55(9), e79-e85.
Yousuf, F. A., Siddiqui, R., Subhani, F., & Khan, N. A. (2013). Status of free-living amoebae (Acanthamoeba spp., Naegleria fowleri, Balamuthia mandrillaris) in drinking water supplies in Karachi, Pakistan. Journal of Water & Health, 11(2), doi: /wh

21. Thank You! Any Questions?
Thank you for your kind attention. I hope you have found this presentation to be useful and will remain mindful of this information as we continue to experience this hot summer weather. Do you have any questions? You can always contact me via , at