Source: IndianExpress

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Context

• Naegleria fowleri, commonly known as the "brain-eating amoeba," is a free-living amoeba that causes primary amebic meningoencephalitis (PAM), a rare and often fatal brain infection.
• This organism thrives in warm freshwater environments and has recently been responsible for the death of a young girl in Kerala, India.

Details

Classification

• Domain: Eukaryota
• Kingdom: Excavata
• Phylum: Percolozoa
• Class: Heterolobosea
• Order: Schizopyrenida
• Family: Vahlkampfiidae
• Genus: Naegleria
• Species: N. fowleri

Morphology

Naegleria fowleri exists in three forms:

• Cyst:
  • Environmentally resistant, dormant form.
  • Spherical shape, thick-walled.
• Trophozoite:
  • Feeding and dividing form.
  • Amoeboid shape with pseudopodia.
  • Infective form in humans.
• Flagellate:
  • Transitional form.
  • Pear-shaped with two flagella.
  • Non-feeding and temporary.

Habitat and Transmission

• Natural Habitat:
  • Warm freshwater bodies such as lakes, rivers, hot springs, and poorly maintained swimming pools.
  • Optimal growth at temperatures up to 115°F (46°C).
• Mode of Transmission:
  • Naegleria fowleri infects humans when contaminated water enters the body through the nose, often during swimming or other water activities.
  • The amoeba travels from the nasal passages to the brain, causing severe infection.
  • Not transmitted through drinking contaminated water or from person to person.

Pathogenesis

• Primary Amebic Meningoencephalitis (PAM): The trophozoite form invades the brain and meninges.

Symptoms of Primary Amebic Meningoencephalitis (PAM)

• Initial Symptoms:
  • Headache
  • Fever
  • Nausea
  • Vomiting
• Progressive Symptoms:
  • Stiff neck
  • Confusion
  • Seizures
  • Hallucinations
  • Coma
• Prognosis:
  • Most individuals with PAM die within 1 to 18 days after symptom onset. The infection typically leads to coma and death within approximately 5 days.

Epidemiology

• Global Occurrence:
  • Found worldwide in warm climates.
  • Extremely rare, with fewer than 200 cases reported in the United States since 1962.
• Incidence in India:
  • 20 reported cases of PAM, with the recent case in Kerala being the seventh in the state.
  • Previous cases have been reported in Alappuzha, Malappuram, Kozhikode, and Thrissur.

Sources:

IndianExpress

PRACTICE QUESTION Q. Which of the following preventive measures can reduce the risk of Naegleria fowleri infection? Avoiding swimming in warm freshwater bodies. Using nose clips while swimming or diving in freshwater. Ensuring proper chlorination and maintenance of swimming pools. Drinking only filtered or bottled water. Select the correct answer using the codes given below: (a) 1, 2, and 3 only (b) 1, 2, and 4 only (c) 2, 3, and 4 only (d) 1, 3, and 4 only Answer: (a)