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Naegleria fowleri infection: Sinus rinses and Primary Amebic Meningitis

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  • Naegleria fowleri infection: Sinus rinses and Primary Amebic Meningitis

    Sinus rinsing is a superb way to deal with allergic rhinitis, sinusitis and asthma, but there are some very serious risks. The following describes this almost always fatal infection:

    I would like to speak with you about a disease called primary amebic meningoencephalitis (PAM). It is a rare and devastating infection of the brain caused by the free-living ameba Naegleria fowleri which has been called the "brain-eating ameba" in the media. First I will give you some brief information on when and where infection often occurs. Then I will discuss the diagnosis and treatment of PAM. Finally, I will tell you about the prevention messages you can share with your patients.

    Naegleria fowleri is commonly found in warm freshwater, such as lakes, rivers, streams, and hot springs. The ameba infects people when contaminated water enters the body through the nose. It then travels up the olfactory nerve to the brain where it causes PAM, which is usually fatal. Infection typically occurs when people go swimming or diving in warm freshwater. In very rare instances, PAM may also occur when contaminated water from other sources, such as inadequately chlorinated swimming pool water or contaminated tap water, enters the nose.

    In the United States there have been 128 PAM cases from 1962 through 2012, with only 1 survivor. Most infections occurred in southern-tier states, with more than half in Texas and Florida. PAM also disproportionately affects males and children, maybe because of the types of water activities (such as diving or watersports) that might be more common among young boys. Recently, cases of PAM have been identified in states as far north as Minnesota, possibly due to rising average water temperatures.

    Although swimming in warm freshwater remains the predominant risk factor for infection, in 2011, 2 cases of PAM in Louisiana, in people who did not have a recent history of swimming in warm freshwater, were found to be regular users of neti pots for sinus irrigation and apparently made their irrigation solutions with Naegleria fowleri-contaminated household tap water.

    In other countries, PAM has occurred in patients who perform ritual nasal rinsing, which is practiced to prepare for prayer in some religions.

    Clinical Features and Diagnosis of PAM

    Clinically, a patient with PAM presents much like a patient with bacterial meningitis, with symptoms of severe headache, fever, vomiting, neck stiffness, and seizures. Cerebrospinal fluid (CSF) studies of patients with PAM typically demonstrate a pattern similar to bacterial meningitis with an elevated opening pressure, a polymorphonuclear pleocytosis, normal or low glucose level, and elevated protein level. Brain imaging is not often helpful in the diagnosis of PAM because findings are often normal early in the course of the disease. When an abnormality is present, it is often cerebral edema.

    The most important clues pointing to the diagnosis of PAM in a patient with the symptoms just described lie in the patient's history. If, in the 2 weeks before presentation, the patient swam in freshwater, such as a lake, river, or stream, during the summer months or performed nasal or sinus irrigation either for medical or religious purposes using untreated tap water, you should consider the diagnosis of PAM.

    Initial testing should include a lumbar puncture to obtain CSF. We recommend preparing a wet mount of the CSF which can demonstrate motile trophozoites of Naegleria fowleri under the microscope.

    Regardless of whether motile amebae are seen, 24/7 diagnostic and treatment consultation is available through CDC. CDC can do testing, including polymerase chain reaction (PCR), to detect Naegleria fowleri DNA in the CSF. Furthermore, if suspected amebae are seen on the wet mount, you can send images of the CSF under the microscope to CDC through our Parasitic Telediagnosis System for examination by one of our microbiologists.

    Although PAM is nearly always fatal, there have been 2 well-documented survivors, one in the United States[5,6] and one in Mexico,[7] who received a combination of drugs with activity against Naegleria fowleri. You can see details about this recommended treatment regimen on CDC's Naegleria Website.

    Preventing Naegleria fowleri Infection

    The only certain way to prevent PAM due to swimming is to refrain from water-related activities in warm freshwater. Additional recommendations that may reduce risk include:

    Hold your nose shut, use nose clips, or keep your head above water when taking part in water-related activities in bodies of warm freshwater;

    Avoid putting your head under the water in hot springs and other untreated thermal waters;

    Avoid water-related activities in warm freshwater during periods of high water temperature and low water levels;

    Avoid digging in, or stirring up, the sediment while taking part in water-related activities in shallow, warm freshwater areas.

    To prevent PAM related to nasal and sinus irrigation for medical or religious purposes, it is important for your patients to understand that tap water from any source is not sterile. When making a solution for irrigating, flushing, or rinsing your nose or sinuses with a neti pot or other device, use water that has been:

    Previously boiled for 1 minute, or boiled for 3 minutes at elevations above 6500 feet, and then left to cool; or

    Filtered, using a filter with an absolute pore size of 1 micron or smaller; or

    Purchased with a label specifying that it contains distilled or sterile water.

    Rinse the irrigation device after each use with water that has been previously boiled, filtered, distilled, or sterilized and leave the device open to air dry completely.

    Jennifer Cope MD
    Experienced Community organizer. Yeah, let's choose him to run the free world. It will be historic. What could possibly go wrong...

    "You're just a jaded cynical mother****er...." Jeffpeg

    (more comments in my User Profile)

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