NAEGLERIA FOWLERI

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