Naegleria fowleri, commonly known as the brain-eating amoeba, has been known to kill more than 140 cases in the United States ranging from 1962-2016. Naegleria fowleri is a free-living amoeba that is rare in humans that in over 10 years, there has only been a recorded of 40 cases reported, where the fatality rate for this disease was and still is above 95%. However, between these years, scientists have been able to gather important information on the environments they thrive in, their life cycle, ways of preventions, and possible treatments for future victims of this brain-eating amoeba.
History of N. fowleri
N. fowleri is a thermophilic water-borne pathogen found in warm lakes, rivers, or any fresh bodies of water. It was originally reported and described as a single-celled protozoan that can thrive in both a free-living environment as well as in a human host, in 1965 by Dr. Fowler and Dr. Carter in Australia. “Free-living amoebae, unlike parasitic amoebae, complete their entire cycle in nature and do not require a host (Farra, Bekondi, Tricou, Robert, & Talarmin, 2017).” It wasn’t until 1966 that another doctor, Dr. Butt, clarified that primary Amoebic Meningoencephalitis was a result from the amoeba N. fowleri. P.A.M is a disease that infects the Central Nervous System, which is compose of the brain and spinal cord, but mostly the frontal lobe of a patient.
N. fowleri Life Cycle
This brain-eating amoeba has a total of three life stages to its life cycle; cyst stage, trophoziote stage, and flagellate stage. The cyst stage is a response of unfavorable conditions like the lack of nutrition, overcrowding, or cold temperature below 10 C in the environment. The next stage is the trophozoite which is the reproductive stage of this amoeba. Scientist identifies this stage by the development of the nucleus or a halo, and now use pseudopodia for mobility. This stage is where the blood cells are phagocytized and is found in the cerebrospinal fluid and tissues. The last stage is the flagellate is a temporary stage that is caused by stress like low supply of food or change in ionic concentration and moves by using a flagellum.
Pathogenesis
N. fowleri are located in all sorts fresh bodies of water because they cannot survive in the salty conditions found in salt waters. The invasion process for N. fowleri begins when “humans are exposed to the organism via swimming, bathing, or other recreational activity during which water is forcefully inhaled into the upper nasal passages (Bright & Gerba, 2017).” Once it is in your nasal cavity, it will attach to the mucous membrane and burrow itself into the olfactory nerve, which is in charge of your sense of smell. It will then migrate to the olfactory bulbs and starts to eat away at the brain tissues and red blood cells using a suction like structures called food-cups. These food-cups uses the process of amoebostomes to cut brain cell membrane to feed off of them. This results in the inflammation and destruction of the brain and brain-lining, necrosis , and hemorrhaging , which has a 97% fatality rate and results in immediate brain death. Many people would think that the death of most patients is the loss of brain activity, but its actually caused by the inflammation of the brain. Eventually, the brain will being suffocate from the pressure of both the skull and the inflamed brain.
Symptoms
Scientist have discovered 2 stages of symptoms, which start 1-9 days after being exposed to the amoeba. Stage 1 include the symptoms of severe frontal headaches, fever, nausea, vomiting, and the loss of smell. The loss of smell is the result from the amoeba attaching the olfactory bulbs and nerve. Stage 2 includes stiff necks; which result from the inflammation of the brain and the tissue around surrounding the, seizures, altered mental status, hallucinations, and can even put the victim into a coma. “Within the brain, N. fowleri causes extensive inflammation, hemorrhage, and necrosis. The time from initial exposure to onset of illness is usually 5–7 days but may be as early as 24 hours, leading to death in 3 to 7 days (Bashyal, Lil, Bains, Debnath, & LaBarbera, 2017).” Due to the fact that these symptoms are very similar to those of bacterial meningitis and because its process is rapid, many physicians do not diagnose the patients with primary Amoebic Meningoencephalitis, P.A.M. “The mortality rate related with primary amoebic meningoencephalitis owing to N. fowleri remains more than 90%. (Siddiqui, Ali, Cope, & Khan, 2016).”
Treatments
Most reported cases are from the United States, Australia, Europe, and France, and out of 132 reported cases in the U.S., there has only been 5 cases with survivors ranging from the years of 1962-2016. What physicians have learned from these survivors is that therapeutic hypothermia, treatment where they get your body temperature below normal, along with the drug Miltefosine really helps with the inflammation of the brain. This results in a full neurologic recovery, and no sign of fatal strain of the amoeba left in the body. Other drugs that have come to use is Amphotericin B, and antifungal drug, and Chlorpromazine, an antipsychotic drug that has shown the best results compared to all the others. In fact, in 2014, scientist was able to sequence the genome for the amoeba, in hope to discover more treatments for future patients.
Preventions
There has been a lot of awareness being spread by the C.D.C, Center for Disease Control, about ways to prevent this from happening to people around the U.S. Great ways to avoid being infected involve wearing a nose piece (water clips) when diving because it will close the amoebas passage way. Also, try your best to not take apart in any water sports being held in warm fresh bodies of waters, and avoid stirring up the sediment in shallow water because it can reveal the amoeba its hidden environment. The most obvious that people need to follow is to not swim in water where swimming is not permitted!
Conclusion
In conclusion, Naegleria fowleri is a rare fatal disease that anyone that has come in contact with contaminated fresh waters especially when water temperatures are high can contract this disease. However, with proper precaution like not participating in any water sports or even diving in the water with a water piece can reduced the chances of getting infected even lower than before. Since the first survivor till now, scientist still thrive to better their research of the amoeba and the awareness for this disease hoping to slowly lower the mortality rate with new discoveries.