PRIMARY AMEOBIC MENINGOENCEPHELITIS

Causative agent

Naegleria fowleri

• morphology

• Mode of transmission

• Habitat

1. Morphology

• Trophozoite stage

→ ameoboid trophozoite : highly Pleomorphic - large central karyosome- lobopodia - causing PAM

→ flagellated trophozoite: pear shaped - two long, whip like flagella - no lobopodia

• cyst stage

→ thick, smooth double wall

2. Mode of transmission

• nasal contamination during water- related activities

Portal of entry→ nose

3. Habitat

• Fresh hot water

Clinical features

1. Prodromal symptoms

• Changes in the taste and smell

• Headache

• High grade fever

• Anorexia, nausea, vomiting

2. Neurological symptoms

• Signs of meningeal irritation: nuchal rigidity, photophobia

• Confusion

• Lack of attention

• Hallucinations

• Seizures

PATHOGENESIS

1. Life cycle of amoeba

• cyst stage ( dormant)

2. Human pathway

• free living amoeboid trophozoite in water

• Human infection by inhalation ( during swimming)

• Penetration of nasal mucosa

• Olfactory nerve infection

• Brain

• Primary amoebic meningoencephalitis

• Death

LABORATORY DIAGNOSIS

1. CSF analysis

2. CSF microscopy

3. Histopathology

4. Culture

5. Flagellation test

6. Molecular method

7. Imaging method

Specimen : CSF

1. CSF analysis

• cloudy and purulent

• Neurophilic pleocytosis

• ⬆protein

• ⬇glucose lvl

2. CSF microscopy

• detect characteristics of trophozoite in CSF confirm the diagnosis

• Wet mount→ actively motile amoeboid trophozoite with blunt lobopodia

• Trophozoite can be demonstrated by direct flourescent antibody staining of the CSF that has been centrifuge using monoclonal antibody

3. Histopathology

• Stained smear for MORPHOLOGICAL CONFIRMATION

• Sample

→ CSF

→ brain biopsy tissue

• stain

→ Giemsa stain = Pleomorphic cell with dark spot karyosome inside a pinkish purple nucleus, surrounded by pale blue cytoplasm

→ H&E

4. Culture

• cultivated on non-nutrient agar , lawn cultured with bacterial supplements like E.coli

• Crawls over lawn cultured of E.coli to produce trail sign

• Observation → clear migratory track on bacterial lawn

• Flagellated test→ confirmation test

5. Flagellation test

• scrap of N.flawleri positive culture is transferred to sterile tube containing distilled water

• Examine under microscope

• Observation→ pear shaped, biflagellated forms

• Confirm Naegleria spp.

6. Molecular method

• multiplex real time - PCR

7. Imaging method

• CT scan

• MRI