Skip to main content

Primary Amebic Meningoencephalitis PAM

Primary Amebic Meningoencephalitis (PAM) is an extremely rare and usually deadly disease caused by infection with a single celled organism (amebae), Naegleria fowleri, which cause inflammation of the lining of the brain and spinal cord. The Naegleria amebae is distributed widely around the world. It is present in soil and in virtually all-natural surface waters such as lakes, ponds and rivers or non-chlorinated pools, discharge or holding basins, and hot springs throughout the world.  Warm water temperatures caused by the hot summer months allow the amebae to multiply. Thus, the risk may be greater in very warm and particularly shallow waters.  Infection with Naegleria is very rare. However, when it does occur, infection is most common during the dry, summer months, when the air temperature is hot, the water is warm, and water levels are low. The number of infections increases during years characterized by heat waves.

PAM infection occurs when water containing the amebae forcefully enters the nose and sinuses. Once in the nasal passages, the amebae move to the brain, where it multiplies causing the symptoms associated with infection. PAM cannot be transmitted from person-to-person.

Symptoms associated with PAM include high fever, headache, nausea, vomiting, lack of appetite, stiff neck, seizures, and coma as the condition worsens. Disturbances to taste and smell may also occur. In most cases, victims are described as primarily young, healthy individuals who have actively participated in a recreational water activity three to seven days prior to onset of symptoms

PAM is a severe illness that does not respond to routine treatments. However, in those rare instances where treatment has been successful, it was started very early in the course of illness. Death generally occurs from three to seven days following infection with the organism. 

Most cases of PAM are young, healthy individuals who have been swimming or playing in water (lakes, rivers, ponds, etc.) three to seven days before they got sick. However, PAM is very rare disease, but individuals should assume there is a risk when entering warm, fresh water. 


  • Avoid water entering nose or mouth when swimming, jumping or diving into bodies of fresh warm water.
  • Hold your nose or use nose plugs when jumping or diving into water.
  • Never swim in stagnant or polluted water.
  • Do not swim in areas posted as "No Swimming".
  • Avoid swallowing water from rivers, lakes, streams, or stock ponds
  • Use earplugs, swim goggles, or masks if you tend to get ear or eye infections.
  • Swim only in properly maintained pools because chlorine rapidly kills the ameba.
  • Keep wading pools clean and change the water daily.
  • Wash open skin cuts and scrapes with clean water and soap.


If you have recently been in warm fresh water and develop symptoms of PAM, seek care from your medical provider immediately. Symptoms usually start 5 days after exposure but can range from 1 to 7 days. Once symptoms start, the disease causes death within about 5 days, but can range from 1-12 days. 

Fact sheet