Pathogenic amoebae and ciliate Dr. Narissara Jariyapan Department of Parasitology Faculty of Medicine Chiang 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 : Flagellates : Flagella Pseudopodia Ciliates : Cilia Sporozoa : Body flexion or Gliding
Amoebae pseudopodia
Flagellates flagella
Ciliates cilia
Sporozoa.......... No locomotive organ Movement by body flexion or gliding
Microsporidia No locomotive organ Polar tube for penetration host cell membrane
Pathogenic amoeba Parasitic : Entamoeba histolytica Free-living : Naegleria fowleri Acanthamoeba spp. Balamuthia mandrillaris
Entamoeba histolytica Disease Distribution Amoebiasis Worldwide esp. tropics
Entamoeba histolytica Trophozoite Size : 20-30 mm Irregular shape 1 spherical nucleus : - small & central karyosome - chromatin granules evenly line nuclear membrane Finely granular endoplasm (food vacuoles + RBC) Rapid movement by finger-like pseudopodia
size : 20-30 mm irregular shape finely granular endoplasm (food vacuoles + RBC) 1 spherical nucleus small & central karyosome chromatin granules evenly line nuclear membrane
Rapid movement by finger-like pseudopodia
food vacuoles + RBC
Entamoeba histolytica Cyst size : 10-20 um round or oval shape thin, tough cyst wall immature mature 1-4 nuclei chromatoid bar with rounded ends-cigar shaped
Cyst chromatoid bar
Life cycle Transmission By ingestion of 4 nuclei cyst
Pathogenesis Amoebiasis : I. Intestinal amoebiasis II. Extraintestinal amoebiasis
I. Intestinal amoebiasis : Asymptomatic cyst passer Amoebic colitis Fulminant colitis Amoeboma, etc.
Amoebic colitis Amoebic colitis (flask shaped) Amoebic dysentery Symptom and sign tenesmus diarrhea mucous bloody fever water depletion secondary bacterial infection
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 - weight loss - hepatomegaly & splenomegaly - jaundice
Liver abscess
Amoebic hepatitis
Diagnosis I. Stool examination : cyst & trophozoite II. Serological test (ELISA) III. Coproantigen detection IV. PCR techniques V. Colonoscopy & Sigmoidoscopy
Amoebic vaginitis
Prevention and control Prevention of transmission : - Early diagnosis and treatment - Good sanitation & personal hygiene
Pathogenic Free-living Amoebae Naegleria fowleri Acanthamoeba spp. Balamuthia mandrillaris*
Naegleria fowleri lobopodium Amoeboid trophozoite 10-12 mm big karyosome with halo Flagellated trophozoite 1-4 flagella cyst
lobopodia Flagellated trophozoite Amoeboid trophozoite Cyst Naegleria fowleri
flagella amoebostome ostiole Flagellated trophozoite 1-4 flagella Amoeboid trophozoite lobopodia Cyst Naegleria fowleri
Life cycle
Transmission CNS infection: Persons with history of swimming Parasites nasopharyngeal mucosa olfactory nerves Brain Primary amoebic meningoencephalitis : acute Symptoms : 3-7 days - fever, headache, rhinitis, stiff neck, seizure, coma Dead within 10 days
Diagnosis Cerebrospinal fluid examination Naegleria fowleri : trophozoite Culture in NNA seeded with intestinal bacteria Brain tissues autopsy found trophozoites with large karyosome, no cyst Histosy of swimming
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%
Acanthamoeba spp. spiky acanthopodia Trophozoite 10-20 mm slow movement Cyst 1 nucleus 2 layers cyst wall
karyosome Trophozoite spiky acanthopodia Cyst 1 nuc. 2 layers of cyst wall Acanthamoeba spp. most common : A. castellani
Trophozoite Cyst Acanthomoeba spp.
Transmission - CNS infection: Parasites Immunocompromised persons - respiratory tract blood stream - genitrourinary tract - skin - mucosa, etc. Brain - Eye (corneal) infection: Immunocompetent persons
Diseases and Symptoms 1. Granulomatous amoebic encephalitis (GAE): subacute Symptoms : fever, headache, neurologic disturbance, seizures Mostly in immunocompromised persons 2. Amoebic keratitis (AK) Symptoms : foreign-body sensation, pain, tearing, photophobia, blepharospasm, blurred vision Clinical features : ocular pain, corneal epithelial breakdown and ringlike corneal infiltrate Mostly in healthy persons
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
Treatment 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 diamidine such as propamidine (0.1%) or hexamidine (0.1%). - Duration of therapy may last six months to a year.
Prevention - Cautious wearing of contact lens - Prompt treatment of lesions in the skin, eyes, genitrourinary or respiratory tract
Disease : Balantidiasis, Balantidiosis Worldwide distribution Largest protozoa found in human
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
Clinical Presentation Parasites - hyaluronidase enzyme - degrade intestinal tissue and facilitates penetration of the mucosa - 2 nd 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
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