Beware the Ides of Summer


Primary Amebic Meningoencephalitis and Naegleria fowleri

Text copyright Ken Ramos, 2004. All rights reserved.


There are numerous pathogenic organisms in our environment no doubt and some are more prolific and are noteworthy enough to be placed on the evening news and be famed as the scourge of mankind, and rightly so. However there is one small, seemingly insignificant organism that crops up from time to time and captures the attention of the public. It occurs during the summer months from June through September when temperatures exceed 80°F. Although kept in the shadows, this organism's claim to fame is Primary Amebic Meningoencephalitis, or PAM for short. PAM is an infectious disease caused by a small, thermophilic, freshwater amoeba known as Naegleria fowleri, which occurs naturally in our environment.

Little is known about N. fowleri but quite a bit is known about the infection that it causes. The infection is acquired by having the amoeba introduced, forcefully, into the nasal passage. This is accomplished by diving into contaminated warm, natural bodies of freshwater. There have been a few reported cases of PAM having been documented without freshwater activity but little or no information on these particular cases is available. Once inside the nasal passage the amoeba, N. fowleri, invades the Central Nervous System infecting the brain of the host causing severe hemorrhaging and swelling of the brain leading to the death of the host.

So, who is at risk for infection from N. fowleri? The risks of encountering N. fowleri are high, while the risk of being infected is low. PAM is a rare infection. It seems that young males are the most susceptible with very few cases reported in females. However, this could be due to the fact that young males are more aggressive in freshwater related activities than females. There has been no evidence of any sexual preference as related to the host. Those with compromised immune systems are highly susceptible to the infection, also.

Now, what are the symptoms of infection and what can be done? The symptoms of PAM usually occur in less than a week. They are as follows:

  • Headache and fever
  • Stiff neck and back
  • Nausea and vomiting
  • Confusion and agitation
  • Photosensitivity
  • Paralysis and seizures
  • Coma and finally death

Most of those who are infected with N. fowleri die within 72 hrs. There is no evidence of the infection being spread from person to person nor is there evidence of self-infection due to the culturing and handling of N. fowleri. For those who may be considering culturing this amoeba, it is strongly recommended that they be very familiar with the Material Safety Data Sheets (MSDS) for the storage and handling of Biological Safety Level 2 organisms.

Recovery from a N. fowleri infection is very slim, it is considered to be 100% fatal, however there have been five reported cases of the host surviving. Aggressive treatment is given using Amphotericin B and Micronozale and other drugs or antibiotics but time is of the greatest importance in treating the infection. At the onset of symptoms, it has been recommended that the individual consult a physician immediately and, if having been involved in freshwater activities such as swimming and diving in warm freshwaters, the physician should be notified of such activities.

Naegleria fowleri can be quite prolific during the hot summer months and can be found in such places as the shallow areas of lakes, slow moving streams and rivers, ponds, and poorly treated swimming pools and spas. Children's small backyard pools, the kind used to splash around in, should not be left standing more than a day, since they can heat rapidly. PAM infections are not uncommon in the United States.

As stated previously, Primary Amoebic Meningoencephalitis is a rare infection and is something to be aware of during the summer months but not to be alarmed over. There have been only about 300 cases of PAM reported worldwide. For more information on PAM and Naegleria consult your local health department or contact the Center for Disease Control (CDC).

At this time I would like to recognize my resources of information concerning PAM and N. fowleri:

  • Office of Laboratory Security, Health Canada
  • Naegleria fowleri: A New Hazard to Recreational Swimmers. Kelly A. Reynolds, Ph. D. Source: Dept. of Human Services, Public Health Division, Gov. of Victoria, Australia.
  • Center for Disease Control, United States of America ( )
  • Amebic Meningoencephalitis, Robert W. Tolan, Jr, MD, Chief of Pediatric Infectious Diseases, Medical Director of the Pediatric Emergency and Hospitalist Programs, Capital Health System; Clinical Associate Professor of Pediatrics, Drexel University College of Medicine.

About the Author

Ken Ramos is a retired U.S. Navy, Petty Officer. He now calls Western North Carolina home, the city of Rutherfordton, after 21 yrs. of naval service. Although his new home has not a "flight deck" or aircraft landing overhead while he is trying to sleep, he is coping fine. His interests lie in the study of Nature and Microorganisms, chiefly Protozoa and as an amateur, is currently researching infectious diseases associated with Protozoa. Leisure activities include fly tying and fly fishing for trout in the mountain streams of Western North Carolina and wilderness hiking.

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