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Naegleria fowleri

Epidemiology: - affects children, young adults who have been swimming or diving in warm (> 80 F) freshwater lakes or pools - 2 cases in 2011 linked to use tap water in Neti pots [3] Pathology: 1) Naegleria enters the brain through the cribriform plate & olfactory bulbs 2) it reaches the frontal lobes where it produces an acute hemorrhagic meningoencephalitis 3) generally fatal within 1 week of symptom onset 4) diagnosis generally made on autopsy a) trophozoites seen in tissue sections b) cysts rarely seen Laboratory: 1) CSF analysis a) trophozoites may be seen on wet mount or stained specimens b) culture 1] non-nutrient agar plates seeded with heat killed bacteria (Entamoeba coli) 2] amoeba ingest bacteria leaving tracks 3] amoeba may be seen under low power microscopy 2) trophozoites a) measure 10-35 um b) large, round central karyosomes c) convert to flagellate forms when exposed to distilled water (after 1-2 hours) 3) cysts a) spherical in shape b) 7-15 um in diameter 4) Naegleria fowleri Ab in CSF 5) Naegleria fowleri DNA 6) see ARUP consult [4] Management: 1) prognosis is uniformly poor 2) only 4 survivors treated with high-dose intravenous & intrathecal amphotericin deoxycholate plus fluconazole, rifampin, azithromycin, miltefosine, & dexamethasone [5]

Related

trophozoite

General

Naegleria

Properties

KINGDOM: animal PHYLUM: protozoa

References

  1. Clinical Diagnosis & Management by Laboratory Methods, 19th edition, J.B. Henry (ed), W.B. Saunders Co., Philadelphia, PA. 1996, pg 1269-70
  2. Harrison's Principles of Internal Medicine, 14th ed. Fauci et al (eds), McGraw-Hill Inc. NY, 1998, pg 1179
  3. Wolchover N Neti pots linked to brain-eating amoeba deaths LiveScience http://vitals.msnbc.msn.com/_news/2011/12/16/9503070-neti-pots-linked-to-brain-eating-amoeba-deaths
  4. ARUP Consult: Acanthamoeba and Naegleria The Physician's Guide to Laboratory Test Selection & Interpretation https://www.arupconsult.com/content/acanthamoeba-and-naegleria
  5. Panosian Dunavan C Hazardous Waters: Lessons From a Brain-Eating Amoeba. Broader education and preventive efforts can help stop N. fowleri in its tracks Medpage Today. July 19, 2022 https://www.medpagetoday.com/opinion/second-opinions/99787
  6. Centers for Disease Control and Prevention Parasites - Naegleria http://www.cdc.gov/parasites/naegleria/faqs.html