Pathogenic amoebae and ciliate

Dr. Narissara JariyapanDepartment of ParasitologyFaculty of MedicineChiang Mai University

Objectives

After the lecture, students must know

1. General morphology of pathogenic amoebae and ciliate

2. Life cycle of Entamoeba histolytica, free living pathogenic amoebae and Balantidium coli

3. Diseases caused by Entamoeba histolytica, free living pathogenic amoebae and Balantidium coli

Classification of Protozoa

Based on locomotive organs :

• Amoebae : Pseudopodia

• Flagellates : Flagella

• Ciliates : Cilia

• Sporozoa : Body flexion or Gliding

pseudopodia

Amoebae

Flagellates

flagella

Ciliates

cilia

.......

.

......

No locomotive organMovement bybody flexion or gliding

Sporozoa

Microsporidia

No locomotive organ

Polar tube for penetrationhost cell membrane

Pathogenic amoeba

Parasitic : Entamoeba histolytica

Free-living :Naegleria fowleriAcanthamoeba spp.Balamuthia mandrillaris

Disease AmoebiasisDistribution Worldwide

esp. tropics

Entamoeba histolytica

Entamoeba histolytica

• Size : 20-30 mm

• 1 spherical nucleus :

- small & central karyosome

- chromatin granules evenly line nuclear membrane

• Finely granular endoplasm

• Rapid movement by finger-like pseudopodia

• Irregular shape

(food vacuoles + RBC)

Trophozoite

chromatin granules evenly line nuclear membrane

finely granular endoplasm

irregular shape

(food vacuoles + RBC)

small & central karyosome1 spherical nucleus

size : 20-30 mm

Rapid movement by finger-like pseudopodia

food vacuoles + RBC

Entamoeba histolytica

round or oval shape

1- 4 nuclei

size : 10-20 um

thin, tough cyst wall

chromatoid bar with rounded ends-Cigar shaped

immature mature

Cyst

Cyst

chromatoid bar

Life cycle

Transmission

By ingestion

of

4 nuclei cyst

I. Intestinal amoebiasis

II. Extraintestinal amoebiasis

Amoebiasis :

Pathogenesis

I. Intestinal amoebiasis :

Asymptomatic cyst passer

Amoebic colitis

Fulminant colitis

Amoeboma , etc.

Amoebic colitis (flask shaped)

Amoebic dysentery

Symptom and sign

tenesmus mucous bloodydiarrhea

fever

water depletion

secondary bacterial infection

Amoebic colitis

Amoebic colitis

Amoebic colitis

rectal biopsy: trophozoite

II. Extraintestinal amoebiasis :

Amoebic hepatitis & liver abscess

Pulmonary amoebiasis

Amoebic brain abscess

Amoebic vaginitis & cervicitis

Amoebic cutis , etc.

Amoebic hepatitis& liver abscess

Most common extraintestinal amoebiasis

- abdominal pain

- fever, diarrhea

- hepatomegaly & splenomegaly

- jaundice

- weight loss

Liver abscess

Amoebic hepatitis

I. Stool examination : cyst & trophozoite

V. Colonoscopy & Sigmoidoscopy

III. Coproantigen detection

IV. PCR techniques

Diagnosis

II. Serological test (ELISA)

Amoebic vaginitis

- Early diagnosis and treatment

- Good sanitation & personal hygiene

Prevention of transmission :

Prevention and control

Pathogenic Free-living Amoebae

Naegleria fowleri

Acanthamoeba spp.

Balamuthia mandrillaris*

cyst

Naegleria fowleri

Amoeboid trophozoite10-12 mmbig karyosome with halo

Flagellated trophozoite1-4 flagella

lobopodium

Naegleria fowleri

Flagellated trophozoite Amoeboid trophozoite Cyst

lobopodia

Naegleria fowleri

Flagellated trophozoite

1-4 flagella

Amoeboid trophozoite

lobopodia

amoebostome

Cyst

ostiole

flagella

Life cycle

Parasites olfactory nerves

Persons with history of swimming

nasopharyngeal mucosa

Brain

CNS infection:

Transmission

Primary amoebic meningoencephalitis : acute

Symptoms : 3-7 days - fever, headache, rhinitis, stiff neck, seizure, coma

Dead within 10 days

Diagnosis

• Culture in NNA seeded with intestinal bacteria

Naegleria fowleri :

• Cerebrospinal fluid examination

• Histosy of swimming

• Brain tissues – autopsy found trophozoiteswith large karyosome, no cyst

trophozoite

Prevention

- Avoid - contact with contaminated water, natural ponds

- Chlorine in swimming pool 1-2 ppm

- Wear nose clip

- Blow nose

Treatment

- Combination anti-microbial therapy: amphotericin B, Azithromycine, rifampin, and azole drugs

- Intensive supportive care – required

- Mortality rate – 100%

Trophozoite

10-20 mm

slow movement

Cyst 1 nucleus

2 layers cyst wall

Acanthamoeba spp.spiky acanthopodia

Cyst 1 nuc. 2 layers of cyst wall

karyosome

Acanthamoeba spp. most common : A. castellani

Trophozoite spiky acanthopodia

Acanthomoeba spp.

Trophozoite Cyst

Transmission

Parasites blood stream- respiratory tract

- skin

- mucosa, etc.

- genitrourinary tract

Brain

Immunocompromised persons

Immunocompetent persons- Eye (corneal) infection:

- CNS infection:

1. Granulomatous amoebic encephalitis(GAE): subacute

Symptoms : fever, headache, neurologic disturbance, seizures

2. Amoebic keratitis (AK)

Clinical features : ocular pain, corneal epithelial breakdown and ringlike corneal infiltrate

Diseases and Symptoms

Mostly in immunocompromised persons

Mostly in healthy persons

Symptoms : foreign-body sensation, pain, tearing, photophobia, blepharospasm, blurred vision

Acanthamoebic keratitis

Diagnosis

1. GAE

- Brain tissues: trophozoites and cysts

- CSF: trophozoites

- Culture in NNA seeded with E. coli

2. AK

- Corneal scraping – staining or culture

- Confocal microscopy

- Molecular techniques - DNA

1. GAE

- Combination anti-microbial therapy: amphotericin B, Azithromycine, rifampin, and azole drugs

2. AK

- A topical cationic antiseptic agent such as polyhexamethylene biguanide (0.02%) or chlorhexidine (0.02%) with or without a diamidinesuch as propamidine (0.1%) or hexamidine (0.1%).

- Duration of therapy may last six months to a year.

Treatment

Prevention- Cautious wearing of contact lens

- Prompt treatment of lesions in the skin, eyes, genitrourinary or respiratory tract

Disease : Balantidiasis, Balantidiosis

Largest protozoa found in human

Worldwide distribution

Trophozoite

• 40-70x50-200 um• Cilia cover around

trophozoite

• 2 nucleus:-- A bean shaped

macronucleus- A less conspicuous

micronucleus

Cyst

• Oval shape• Thick cyst wall

45-75 um

• 2 nucleus:--Macronucleus-Micronucleus

Balantidium coli

Balantidium coli cyst and trophozoite(in a wet mount at 1000x)

Life cycle

• Habitat : large intestine of human, pig, monkey•Infective stage : cyst• Replication by transverse binary fission or conjugation

• Parasites - hyaluronidase enzyme - degrade intestinal tissue and facilitates penetration of the mucosa - 2nd infections

• Asymptomic

• Symptoms - chronic diarrhea, occasional dysentery (blood or mucus), nausea, foul breath, colitis, abdominal pain, weight loss, deep intestinal ulcerations, and possibly perforation of the intestine (similar to amebic dysentery)

• Dysentery due to bleeding - shock and death

Clinical Presentation

Mucosa of large intestine (cecum and colon) - ulcerations

Sigmoidoscopy

Treatment

• Tetracyclines

• Metronidazole

• Iodoquinol

Public Health Interventions

• Prevented by improved hygiene practices, water sanitation, and proper disposal of fecal material

• Asymptomatic carriers should be treated with antibiotics along with symptomatic patients