Description

Source: TimesofIndia
Disclaimer: Copyright infringement not intended.
Context
- Amoebic meningoencephalitis, specifically Primary Amoebic Meningoencephalitis (PAM) caused by Naegleria fowleri, is a rare but fatal infection affecting the brain and its surrounding tissues.
- The Kerala government has issued a warning due to increased cases following the continued rains in the region.
Details
Amoebic Meningoencephalitis
- Amoebic meningoencephalitisis a rare but serious infection of the brain and its surrounding structures, caused by certain free-living amoebae.
- There are two main forms:
- Primary Amoebic Meningoencephalitis (PAM)
- Granulomatous Amoebic Encephalitis (GAE)
Types of Amoebic Meningoencephalitis
Primary Amoebic Meningoencephalitis (PAM)
- Causative Agent:Naegleria fowleri
- Epidemiology:Commonly found in warm freshwater bodies like lakes, rivers, and hot springs. Mostly affects healthy young individuals.
- Transmission:Inhalation of contaminated water through the nose during swimming or other water activities.
- Incubation Period:1-9 days
- Symptoms:Severe headache, fever, nausea, vomiting, stiff neck, confusion, seizures, and hallucinations.
- Progression:Rapid, leading to death within 5-7 days if untreated.
Granulomatous Amoebic Encephalitis (GAE)
- Causative Agents:Acanthamoeba species, Balamuthia mandrillaris, and Sappinia pedata.
- Epidemiology:Found in soil, dust, and freshwater. More commonly affects immunocompromised individuals.
- Transmission:Through cuts, wounds, or inhalation of contaminated dust or soil.
- Incubation Period:Weeks to months
- Symptoms:Similar to PAM but with a slower progression. Symptoms include headache, low-grade fever, altered mental status, and neurological deficits.
- Progression:Chronic and progressive, often leading to death over several weeks to months.
Pathophysiology
- Naegleria fowleri:Invades the central nervous system (CNS) via the olfactory nerve after being inhaled through the nose. Causes rapid destruction of brain tissue.
- Acanthamoeba & Balamuthia:Enter through the bloodstream and form granulomas, which are clusters of immune cells attempting to wall off the infection.
Treatment
- Primary Amoebic Meningoencephalitis (PAM):
- Medications:Amphotericin B, Miltefosine, Rifampin, Fluconazole, and Azithromycin.
- Supportive Care:Intensive care unit (ICU) support for managing symptoms.
- Granulomatous Amoebic Encephalitis (GAE):
- Medications:Combination therapy with Pentamidine, Sulfadiazine, Flucytosine, Fluconazole, and Miltefosine.
- Supportive Care:Management of symptoms and complications.

Prevention
- Avoidance:Refrain from swimming in warm freshwater bodies, especially during high-temperature periods.
- Protective Measures:Use of nose clips or keeping the head above water when swimming.
- Water Treatment:Proper chlorination and maintenance of swimming pools and other recreational water facilities.
Amoeba
- Amoeba is a type of single-celled organism classified under the domain Eukaryota, kingdom Protista.
- They are simple, microscopic organisms that are found in a variety of environments, including fresh and saltwater, soil, and as parasites in other organisms.
Classification
- Domain:Eukaryota
- Kingdom:Protista
- Phylum:Amoebozoa
Morphology
- Shape and Structure:Amoebae have a flexible, irregular shape due to the absence of a rigid cell wall.
- Cell Components:
- Plasma Membrane:A flexible outer boundary that encloses the cell contents.
- Cytoplasm:Divided into ectoplasm (outer, clear, and gel-like) and endoplasm (inner, granular, and fluid-like).
- Nucleus:Controls cell activities and contains genetic material.
- Pseudopodia:Temporary, foot-like extensions of the cytoplasm used for movement and feeding.
- Contractile Vacuole:Expels excess water to maintain osmotic balance.
- Food Vacuoles:Contain ingested food particles for digestion.
Physiology
- Movement:Amoebae move using pseudopodia, which are extended and retracted to propel the cell forward. This type of movement is known as amoeboid movement.
- Feeding:Amoebae are heterotrophic and ingest food through a process called phagocytosis. They engulf food particles with pseudopodia, forming food vacuoles where digestion occurs.
- Respiration:Gas exchange occurs through simple diffusion across the cell membrane.
- Excretion:Waste products and excess water are expelled through the contractile vacuole.
Reproduction
- Asexual Reproduction:Amoebae primarily reproduce by binary fission, where the nucleus divides by mitosis, followed by the division of the cytoplasm (cytokinesis), resulting in two daughter cells.
- Encystment:Under unfavorable conditions, some amoebae form cysts, which are dormant, resistant structures that protect the cell until conditions improve.
Habitat and Ecology
- Aquatic Environments:Freshwater and marine habitats, including ponds, lakes, and rivers.
- Soil:Moist soil provides a suitable environment for many amoebae.
- Parasitic Species:Some amoebae, like Entamoeba histolytica, are parasitic and cause diseases in humans and animals.
Importance
- Soil Health:Amoebae contribute to nutrient cycling and soil fertility by decomposing organic matter.
- Research:Used as model organisms in biological research due to their simple structure and functions.
- Diseases:Some amoebae cause diseases in humans, such as:
- Amoebic Dysentery:Caused by Entamoeba histolytica, leading to severe diarrhea and abdominal pain.
- Amoebic Meningoencephalitis:Caused by Naegleria fowleri and Acanthamoeba species, affecting the central nervous system.
Sources:
TimesofIndia
PRACTICE QUESTION
Q: With reference to amoebic meningoencephalitis, consider the following statements:
- Amoebic meningoencephalitis is primarily caused by Naegleria fowleri, which is commonly found in warm freshwater environments.
- The primary route of infection for Naegleria fowleri is through the ingestion of contaminated water.
- Symptoms of primary amoebic meningoencephalitis (PAM) typically include headache, fever, nausea, and vomiting, followed by severe neurological symptoms such as seizures and hallucinations.
Which of the statements given above is/are correct?
a) 1 only b) 1 and 2 only c) 1 and 3 only d) 1, 2, and 3
Answer: c)
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