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'''Naegleria fowleri''' (pronounced //) is a free living amoeba typically found in warm fresh water, from 25-35 degrees Celsius in an amoeboid or temporary flagellate stage. It belongs among a group called the Percolozoa or Heterolobosea.

Contents

Infection

Detection

Cultural references

References

External links

Infection

In humans, ''N. fowleri'' can become pathogenic, causing Primary Amoebic Meningoencephalitis (PAM or PAME), a syndrome affecting the central nervous system, characterized by changes in olfactory 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 central nervous system via penetration of the olfactory mucosa and nasal tissues, resulting in significant necrosis of and hemorrhaging in the olfactory bulbs. From there, amoebae climb along nerve fibers through the floor of the cranium and into the brain. Amphotericin B is currently the most effective known pharmacologic treatment for ''N. fowleri'', but the prognosis remains bleak for those that contract PAM, as only eight 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 rifampicin. A more aggressive antibody serum-based treatment is being pursued, and may eventually prove more effective than modern broad-spectrum antibiotic targeting. At this time, though, timely diagnosis remains a very significant impediment to the successful treatment of infection, as most cases have only been appreciated post-mortem.

Detection

''N. fowleri'' can be grown in several kinds of liquid axenic media or on non-nutrient agar plates coated with bacteria. Detection in water is performed by centrifuging a water sample with ''Escherichia coli'' added, and then applying the pellet to a non-nutrient agar plate. After several days the plate is microscopically inspected and ''Naegleria'' cysts are identified by their morphology. Final confirmation of the species' identity can be performed by various molecular or biochemical methods.^[1]

Cultural references

★ ''Naegleria fowleri'' was featured on the TV show ''House'', on season 2, episodes 20-21. The writers got the most dramatic symptom wrong. Both characters developed cortical blindness, a condition affecting the occipital lobes where the patient thinks he can see but really can not. This is not consistent with Naegleria fowleri, whose initial symptoms are "alteration in taste (ageusia) or smell (parosmia)".^[2] Also, this infection currently only seldomly responds to treatment, and the vast majority of treated cases result in death, even if caught early.

★ A "brain-eating amoeba" in Lake Pleasant was mentioned on the X-files season 1, 'Darkness Falls'

References

1. Rapid Detection and Enumeration of Naegleria fowleri in Surface Waters by Solid-Phase Cytometry -- Pougnard et al. 68 (6): 3102 -- Applied and Environmental Microbiology
2. eMedicine - Naegleria Infection : Article by Barnett Gibbs, MD

External links

★ Naegleria Infection fact sheet - CDC.gov