Naegleria is an ameba commonly found in the environment in water and soil. Infection of humans is rare but serious. To prevent infection with Naegleria, precautions should be taken to ensure that water does not enter the nose when participating in recreational water sports. Most patients with PAM have a history of water exposure that includes swimming or diving through a body of fresh water. In arid climates, cases have arisen from the inhalation of cysts. Trophozoites or cysts, which give rise to trophozoites after they excyst, penetrate the nasal mucosa and ascend along the olfactory nerves after phagocytosis by sustentacular cells of the neuroepithelium and pass through the cribriform plate to invade brain tissue with resultant purulent meningitis and encephalitis.
Naegleria infection is caused by the amoeba Naegleria fowleri a microscopic organism that lives in fresh water and soil. Naegleria infection most often occurs when the naegleria amoeba enters your body through your nose while swimming or participating in water sports. Once inside your nose, the amoeba makes its way to your brain. There, it causes inflammation and destroys brain tissue. Naegleria infection is very rare. Only 31 cases occurred in the United States between 1989 and 2002. About 200 cases of naegleria infection have been reported worldwide.
Infection with Naegleria causes the disease primary amebic meningoencephalitis (PAM), a brain inflammation, which leads to the destruction of brain tissue. Initial signs and symptoms of PAM include headache, fever, nausea, vomiting, and stiff neck. As the ameba causes more extensive destruction of brain tissue this leads to confusion, lack of attention to people and surroundings, loss of balance and bodily control, seizures, hallucinations. The disease progresses rapidly and infection usually results in death within 3 to 7 days.
Headache, fever, nausea and vomiting, stiff neck, confusion, lack of attention to people and surroundings, loss of balance and bodily control, seizures, and hallucinations are signs and symptoms of infection. Naegleria fowleri infection is also called primary amebic meningoencephalitis (PAM). Symptoms worsen; infection usually results in death within 7-10 days.
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 increase during years characterized by heat waves. Infection with Naegleria occurs when the ameba enters the body through the nose. Generally this occurs when people are participating in water-related activities such as swimming underwater, diving, or other water sports that result in water going up the nose. The ameba then travels to the brain and spinal cord where it destroys the brain tissue.
Recreational water users should assume that there is always a low level of risk whenever they enter warm freshwater (for example swimming, waterskiing) in southern tier states. Posting signs is unlikely to be an effective way to prevent infections. This is because the location and number of amebae in the water can vary a lot over time. In addition, posted signs might create a misconception that bodies of water without signs are Naegleria-free. Information about the risks of Naegleria infection should be put into public health messages discussing general issues of water safety and risk.
