Recently, there have been two deaths in Louisiana because of a fatal infection called primary amoebic meningoencephalitis (PAM), which is caused by a insidious amebic species named Naegleri fowleri. This is highly disconcerting and, thus, has received a significant amount of attention in the news. However, the magnitude of the threat is comparatively small in relation to the attention it receives. Moreover, the tragic deaths in Louisiana were very avoidable— resulting from the improper use of tap water in nasal irrigation devices, i.e. Neti pots.
Amoeba and Human Pathologies
Only four genera of amoeba can cause human disease: Acanthamoeba spp., Balamuthia, Naegleria, and Sappinia. Acanthamoeba spp., and Balamuthia mandrillaris are only opportunistic pathogens, meaning that they can only cause infections in individuals with weakened immune systems such as individuals taking immunosuppressant drugs or individuals with AIDS. However, other species of Balamuthia have been associated with pathologies in children with competent immune systems, and one species of Acanthamoeba spp., Acanthamoeba Keratitis, can cause eye infections, often in contact-wearing individuals. Sappinia diploidea was thought to have caused a single cause of encephalitis in a 38 year old man, but scientists and doctors have later identified that the actual species that caused the encephalitis was Sappinia pedata. Ultimately, Naegleri proves to be the deadliest genus and the perpetrator of these two Louisiana deaths, though, Naegleri fowleri is the only pathogenic species of the 30 species within the genus.
Naegleri fowleri
Naegleri fowleri is usually found in natural freshwater bodies of water such as lakes and ponds that have especially warm temperatures because Naegleri fowleri grows best at 42 ?C. Naegleri fowleri enters the human body via the nasal passages from the forcible entrance of water, but as the cases in Louisiana have shown Naegleri fowleri can also persist in heated tap water or even swimming pools with insufficient chlorination. After Naegleri fowleri has enter the body it will cause hemorrhaging of the olfactory bulb and then climb into the cranium, where it becomes pathogenic by eating away at neural tissue.
Almost as soon as the amoeba begins to eat away at the brain, PAM onsets, which can occur within a day or two weeks of being exposed to this amoeba. Several symptoms are associated with PAM: headache, fever, nausea, vomiting, ataxia, seizures, confusion, and hallucinations. PAM progress rapidly and death is almost inevitable after a week or two.
Treatment Options
The unfortunate truth is that there are very few, if any, effective treatment options; almost all patients diagnosed with PAM die. The CDC recommends the use of Amphotericin B or Chlorpromazine with Chlorpromazine showing a little more promise, especially therapeutically. If the infection is caught early a combination of tetracycline, miconazole, and sulfadiazine has shown to be somewhat successful, but most infections from Naegleri fowleri are not even diagnosed until the patient has already died. The only prevention option that has been tendered is the use of nose clips with recreation in freshwater bodies. Moreover, the use of distilled water or sterilized water with Neti pots will entirely avoid infection especially with efficient cleaning of the device.
Sources
- Center for Disease Control and Prevention
- Visvesvar GS, H Mouraz, FL Schuster. (2007) Pathogenic and opportunistic free-living amoebae: Acanthamoeba spp., Balamuthiamandrillaris, Naeglieria fowleri, and Sappinia diploidea. FEMS Imunol Med Microbiol. 50: 1-26.
- Wolchover, Natalie. Neti pots linked to brain-eating amoeba deaths. Live Science. Dec. 17, 2011.
Join the Conversation