Naegleria fowleri is a free living, pathogenic amoeba typically found in warm fresh water, from 25-35 degrees Celsius. It belongs among a group called the Percolozoa or Heterolobosea. In humans, N. fowleri is responsible for primary amoebic meningoencephalitis (PAM), a syndrome affecting the central nervous system, characterized by changes in olifactory perception (taste and smell), followed by vomiting, nausea, fever, headache, and the rapid onset of coma and death.

PAM usually occurs in healthy children or young adults with no prior history of immunocompromisation who have recently been exposed to bodies of fresh water. N. fowleri invades the CNS via penetration of the olfactory mucosa and nasal tissues, resulting in significant necrosis of and hemorrhaging in the olfactory bulbs. For those unlucky enough to be among the few who contract PAM, the prognosis is bleak, as only six patients have survived in a clinical setting. Amphotericin B devastates N. fowleri organisms in laboratory settings, and is the preferred choice in N. fowleri treatment, in addition to systemic rifampin. A more aggressive antibody serum based treatment is being pursued, and may eventually prove more effective than modern broad antibiotic targeting.