Primary amoebic meningoencephalitis overview
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Primary amoebic meningoencephalitis is a disease of the central nervous system caused by infection from Naegleria fowleri.[1] Naegleria fowleri is a free-living ameboflagellate that invades the brain and meninges via the nasal mucosa and olfactory nerve to cause acute, fulminant hemorrhagic meningoencephalitis (primary amebic meningoencephalitis – PAM), primarily in healthy children and young adults with a recent history of exposure to warm fresh water. Initial signs and symptoms of PAM begin 1 to 14 days after infection and include sudden onset of headache, fever, nausea, vomiting, and stiff neck accompanied by positive Kernig’s and Brudzinski’s signs. In some cases, abnormalities in taste or smell, nasal obstruction and nasal discharge might be seen. Other symptoms might include photophobia, mental-state abnormalities, lethargy, dizziness, loss of balance, other visual disturbances, hallucinations, delirium, seizures, and coma. After the onset of symptoms, the disease progresses rapidly and usually results in death within 3 to 7 days. Although a variety of treatments have been shown to be active against amoebae in vitro and have been used to treat infected persons, most infections have still been fatal.
Historical Perspective
Primary amoebic meningoencephalitis was first documented in Australia in 1965.[2][3] In 1966, four cases were reported in the USA.
Pathophysiology
Naegleria fowleri is a heat-loving (thermophilic), free-living ameba (single-celled microbe), commonly found around the world in warm fresh water (like lakes, rivers, and hot springs) and soil that causes acute, fulminant hemorrhagic meningoencephalitis (primary amebic meningoencephalitis – PAM). Naegleria fowleri is the only species of Naegleria known to infect people. Most of the time, Naegleria fowleri lives in freshwater habitats by feeding on bacteria. However, in rare instances, the ameba can infect humans by entering the nose during water-related activities. Once in the nose, the ameba travels to the brain and causes a severe brain infection, primary amoebic meningoencephalitis (PAM), which is usually fatal.
References
- ↑ Cabanes PA, Wallet F, Pringuez E, Pernin P (2001). "Assessing the risk of primary amoebic meningoencephalitis from swimming in the presence of environmental Naegleria fowleri". Appl. Environ. Microbiol. 67 (7): 2927–31. doi:10.1128/AEM.67.7.2927-2931.2001. PMC 92963. PMID 11425704. Unknown parameter
|month=ignored (help) - ↑ Fowler M, Carter RF (1965). "Acute pyogenic meningitis probably due to Acanthamoeba sp.: a preliminary report". Br Med J. 2 (5464): 740–2. PMC 1846173. PMID 5825411. Unknown parameter
|month=ignored (help) - ↑ Symmers WC (1969). "Primary amoebic meningoencephalitis in Britain". Br Med J. 4 (5681): 449–54. doi:10.1136/bmj.4.5681.449. PMC 1630535. PMID 5354833. Unknown parameter
|month=ignored (help)