Naegleria fowleri
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 Different stages of Naegleria fowleri
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| Naegleria fowleri Carter (1970) |
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Naegleria fowleri (also known as the brain eating amoeba) is a ubiquitous, free living amoeba typically found in warm, fresh water, (25–35 °C / 77–95 °F) in an temporary, amoeboid, flagellate stage. It belongs to a group called the Percolozoa or Heterolobosea. N. fowleri causes primary amebic meningoencephalitis (PAP), a rare disease whereby N. fowleri tinvades the human central nervous system through the cibriform plate and causes fulminant fatal meningoencephalitis in almost all cases.[1][2]
Infection
In humans, N. fowleri can invade the central nervous system via the nose, more specifically the olfactory mucosa and nasal tissues. The penetration initially results in significant necrosis of and hemorrhaging in the olfactory bulbs. From there, amoebae climb along nerve fibers through the floor of the cranium via the cribriform plate and into the brain. It then becomes pathogenic, causing primary amoebic meningoencephalitis (PAM or PAME). PAM is 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 in two weeks.
PAM usually occurs in healthy children or young adults with no prior history of immune compromise who have recently been exposed to bodies of fresh water.
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 (3% survival rate) in a clinical setting. Amphotericin B devastates N. fowleri organisms in laboratory settings; it, in combination with systemic rifampicin, is the preferred choice in N. fowleri treatment.
A more aggressive antibody serum-based treatment is being pursued, and may eventually prove more effective than modern broad-spectrum antibiotic targeting.
Timely diagnosis remains a very significant impediment to the successful treatment of infection, as most cases have only been appreciated post-mortem. It killed 23 people in the US from 1995 to 2004, and has killed six in the year of 2007 (3 in Florida, 2 in Texas, and 1 in Arizona).
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.[3] Confirmation of Naegleria presence can be done by so called flagellation test, when amoeba is exposed to hypotonic environment (distilled water). Naegleria in contrast to other amoebae differentiates within two hours into flagellar state. Pathogenicity can be further confirmed by exposition to high temperature (42°C), where is Naegleria fowleri as pathogenic species of Naegleria able to grow in contrast to Naegleria gruberi etc.
Antimicrobial Regimen
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- Preferred regimen: Amphotericin B 1.5 mg/kg/day bid for 3 days; then 1 mg/kg/day for 6 days AND 1.5 mg/day intrathecal for 2 days; then 1 mg/day intrathecal qd for 8 days.
- Note: Investigational drug called miltefosine also available for treatment.
Incidents and outbreaks
Czech Republic
- Between years 1962–1965, 16 young persons died of acute meningoencephalitides in Ústí nad Labem as a consequence of bathing in an indoor swimming pool.[6]
United States
According to the Centers for Disease Control and Prevention, the amoeba killed 23 people between 1995 and 2004.
- In August 2005, two Oklahoma boys, ages 7 and 9 were killed by N. fowleri after swimming in hot stagnant water of the lakes in the Tulsa area.[7]
- In 2007, six cases were reported in the U.S., all fatal:[8]
- In July, the amoeba caused the deaths of three boys in lakes around Orlando, Florida. Possible causes of the infections include higher temperature and droughts in that area of Florida.[9]
- In late summer, the amoeba caused the death of a 12-year-old boy and a 22-year-old young man in Lake LBJ in Texas.[10][2]
- In September, a 14-year-old boy was killed by the amoeba after likely having caught it while swimming in Lake Havasu in Arizona. The doctors suspected meningitis before the boy died, but did not know the etiology until the CDC confirmed it as N. fowleri.[11][12]
Pop culture references
- Naegleria fowleri was featured on the TV show House, in a two-part season 2 episode ("Euphoria" parts 1 and 2). The writers took dramatic license with one of the disease's symptoms. Both characters developed Anton's blindness, a condition affecting the occipital lobes where the patient thinks he can see but really cannot. This is not consistent with N. fowleri, whose initial symptoms are "alteration in taste (ageusia) or smell (parosmia)".[13]
- A "brain-sucking amoeba" that infects swimmers was mentioned in the season 1 episode of The X-files, "Darkness Falls"
References
- ↑ "The Centers for Disease Control and Prevention, Division of Parasitic Diseases - Naegleria Infection Fact Sheet". Retrieved 2007-10-09.
- ↑ "6 Die From Brain-Eating Amoeba in Lakes". Retrieved 2007-10-03.
- ↑ Pougnard; et al., "Rapid Detection and Enumeration of Naegleria fowleri in Surface Waters by Solid-Phase Cytometry", Applied and Environmental Microbiology, 68 (6), pp. 3102–3107, retrieved 2007-07-18
- ↑ Gilbert, David (2015). The Sanford guide to antimicrobial therapy. Sperryville, Va: Antimicrobial Therapy. ISBN 978-1930808843.
- ↑ Template:Citeweb
- ↑ Červa, L. (April 5, 1968). "Ameobic meningoencephalitis: sixteen fatalities". Science. 160: 92. Unknown parameter
|coauthors=ignored (help); Check date values in:|date=(help) - ↑ "Parasitic Infection Kills Two Tulsa Swimmers". Retrieved 2005-08-06.
- ↑ Six Die From Brain-Eating Amoeba in Lakes, an Associated Press article via The Washington Post
- ↑ "Deadly amoeba lurks in Florida lakes". Retrieved 2007-07-19.
- ↑ "Deadly lake disease causing concern in Texas". Retrieved 2007-09-10.
- ↑ "Brain-Eating Amoeba Kills Arizona Boy". Retrieved 2007-09-27.
- ↑ "Arizona Teen Becomes Sixth Victim This Year of Brain-Eating Amoeba". Retrieved 2007-09-27.
- ↑ Barnett Gibbs, MD. "Naegleria Infection". emedicine. Retrieved 2007-07-19. Unknown parameter
|coauthors=ignored (help)
External links
- Naegleria Infection fact sheet from the website of the Centers for Disease Control and Prevention
it:Naegleria fowleri ca:Naegleria fowleri de:Naegleria fowleri sv:Naegleria fowleri