Naegleriasis, also known as primary amoebic meningoencephalitis (PAM), is an almost invariably fatal infection of the brain by the free-living protozoan Naegleria fowleri.

[6][1] N. fowleri is typically found in warm bodies of fresh water, such as ponds, lakes, rivers and hot springs.

[6] Initial symptoms include changes in taste and smell, headache, fever, nausea, vomiting, back pain,[9] and a stiff neck.

[3] Scientists speculate that lower age groups are at a higher risk of contracting the disease because adolescents have a more underdeveloped and porous cribriform plate, through which the amoeba travels to reach the brain.

[5] N. fowleri invades the central nervous system via the nose, specifically through the olfactory mucosa of the nasal tissues.

This usually occurs as the result of the introduction of water that has been contaminated with N. fowleri into the nose during activities such as swimming, bathing or nasal irrigation.

[citation needed] Primary amoebic meningoencephalitis presents symptoms similar to those of relatively common bacterial and viral meningitis.

Endogenous cytokines, released in response to the pathogens, affect the thermoregulatory neurons of the hypothalamus causing a rise in body temperature.

[15] Additionally, the cytokines may act on the vascular organ of the lamina terminalis, leading to upregulation of Prostaglandin E2 contributing to hyperthermia.

[15] The increase in intracranial pressure stimulates the area postrema to create nausea sensations which may lead to brain herniation and damage to the reticular formation.

N. fowleri can be grown in several kinds of liquid axenic media or on non-nutrient agar plates coated with bacteria.

[22] Confirmation of Naegleria presence can be done by a so-called flagellation test, where the organism is exposed to a hypotonic environment (distilled water).

[citation needed] Michael Beach, a recreational waterborne illness specialist for the Centers for Disease Control and Prevention, stated in remarks to the Associated Press that wearing of nose clips to prevent insufflation of contaminated water would be effective protection against contracting PAM, noting that "You'd have to have water going way up in your nose to begin with".

[5] Treatment has often also used combination therapy with multiple other antimicrobials in addition to amphotericin, such as fluconazole, miconazole, rifampicin and azithromycin.

[5] It only has variable activity in vitro and it has strong effects on the therapeutic levels of other antimicrobials used by inducing cytochrome p450 pathways.

On the other hand, another survivor, an 8-year-old male, was diagnosed several days after symptoms appeared and was not treated with targeted temperature management although he was administered miltefosine.

[4][27] As of 2015[update] the U.S. CDC offered miltefosine to doctors for the treatment of diseases caused by free-living amoebas including Naegleria,[4] despite a lack of any data on how well the drug reaches the central nervous system.

[5] In 2018, a 10-year-old girl in the Spanish city of Toledo became the first person to contract the disease in Spain, and was successfully treated using intravenous and intrathecal amphotericin B.

[29][30] Since its first description in the 1960s, only seven people worldwide have been reported to have survived PAM out of 450 cases diagnosed, implying a fatality rate of about 98.5%.

[39] It was not until 1965 that doctors Malcolm Fowler and Rodney F. Carter in Adelaide, Australia, reported the first four-human cases of amoebic meningoencephalitis.