FREE LIVING AMOEBA DR. HALA ELNAHAS PBL 4 AZFAR FATHULLAH FIRDAUS REZA NOREEN SAFWA BALQIS SARAH ANEESA INTAN HANIE

PATHOGENIC FREE LIVING AMOEBA

OBJECTIVES:  Types of amoeba  General characters of free living amoeba  Definition of amphizoic amoeba  Naegleria fowleri and Acanthamoeba -Characters -Habitat -Morphology -Mode of infection -Pathogenesis -Clinical picture -Diagnosis -Treatment -Prevention

Amoeba Parasitic Free living Pathogenic E. Histolytica Commensal Entamoeba coli Iodamoeba butschili Naegleria fowleri Acanthamoeba castellani

 Free living amoebae comprise a large group of protozoa living in moist soil, decaying vegetation and in all types of water, especially water containing bacteria.  Several species have been observed as human symbionts without pathological consequence, although some of them may result in severe disease.  Two genera are known to produce diseases in man: 1- Naegleria fowleri (an amoeboflagellate). 2- Acanthamoeba castellani. GENERAL CHARACTERS OF FREE LIVING AMOEBA

Naegleria fowleri

Acanthamoeba castellani

AMPHIZOIC AMOEBA  They have also been called amphizoic amoebae because these amoebae have the ability to exist as free-living organisms in nature and only occasionally invade a host and live as parasites within host tissue.

CharacterNaegleria fowleriAcanthamoeba Forms3 stages Trophozoite Flagellate Cyst 2 stages Trophozoite Cyst TrophozoiteActively mobileSluggishly mobile CystRoundPolyhedral

Naegleria fowleriAcanthamoeba HABITATEnvironment: Soil and fresh water Man: CNS Environment: soil,dust and fresh water In man: CNS,eyes,skin,lungs MORPHOLOGY  Amoebo- flagellate 1)Trophozoite a.Amoebic : Trophozoite takes the amoebic form in tissues and CSF Both stages may exist in the environment and tissues 1)Trophozoite 10-40µ Pseudopodia are in the form of multiple small spiky processes surrounding the body Nucleus has large central karyosome

Naegleria fowleriAcanthamoeba Size 10-15µ,nucleus has large central karyosome and no peripheral chromatin Multiplication by longitudinal binary fission b) Flagellate: Amoeba changes to flagellated form if get in contact with warm water/CSF 2 long equal flagellae c) Cyst In soil, never in tissues Rounded,7-10µ, uninucleated Wall is smooth,has no pores b)Cyst 15-20µ,more or less rounded Has double wall,outer smooth irregular ectocyst and inner rough polyhedral endocyst provided with many pores (osteoles) It is mononucleated It can exist in the tissues

Naegleria fowleriAcanthamoeba MODE OF INFECTION Through the nasal route 1.Swimming or sniffing in contaminated water 2.Inhalation of contaminated air -Trophozoite in contaminated water enters the nose  migrates through the nasal mucosa  cribriform plate  olfactory nerve  olfactory pulp  base of the brain  disseminates to the brain tissue Mode of infection: Inhalation of aerosol or dust containing cyst or trophozoites Invasion through broken skin Sniffing in contaminated water Corneal trauma, prolonged use of contact lenses Portal of entry: Skin,mucosal ulcer,lung inhalation or cornea

PATHOGENESIS PAM ( Primary Amoebic Meningo- encephalitis) Children & young adult Previously healthy Headache, temp ⁰ C 1)Granulomatous amoebic encephalitis Affect immunocompromised person Tissue contain trophozoite, cyst and multinucleated giants cell 2) Amoebic keratitis Trophozoite & cyst are present in corneal tissues 3)Chronic granumalatous skin ulcer

Amoeba affecting brainAmoeba affecting skin 1ry amoebic meningoencephalitis (PAM) Granumolatous amoebic encephalitis Amoebic brain abcess Granulomatous skin ulcer Cutaneous amoebiasis

Pathogenesis and Clinical Picture Amoeboid trophozoite Nasal mucosa Cribriform plate Olfactory nerve Brain, meninges Diffuse meningoencephalitis with haemorrhage and necrosis of brain tissue Fever, headache, nausea, vomiting, stiffness of neck (Kernig’s sign), convulsions. Disturbance in the sense of smell and taste Coma and death within 3-6 days from infection Thus Naegleria causes acute fulminant rapidly fatal disease 20

Acanthamoeba species Granulomatous Amoebic Encephalitis Acanthamoeba Keratitis 21

 Diffuse meningoencephalitis.  Runs rapidly fatal course (death within 3-6 days)  History of swimming in natural water or swimming pools.  Focal, granulomatous, space-occupying lesion.  Runs sub-acute or chronic course (lasts for weeks, months or years)  Not strongly associated with swimming. Naegleria meningoencephalitis Acanthamoeba encephalitis Children & young adults Debilitated Chronically ill low immunity 22

DIAGNOSIS Recent History Laboratory diagnosis 1. Brain tissue biopsy 2. CSF Examination 3. CSF culture 4. Animal inoculation Serodiagnosis not useful Brain tissue & CSF : Trophozoite & cyst Culture on non nutrient agar CSF elevated protein, normal or decrease glucose Corneal scrapping Culture of contact lens saline IFA of tissue Ct multiple brain focal tissue TREATMENT No satisfactory treatment Hospitalization Palliative treatment Amphotericin B + Miconazole or Rifampicin No effective treatment is available Sulfadiazine,penicillin and chloramophenicol In keratitis, drug is effective (ketoconazole) + topical application ( miconazole followed keratoplasty

PREVENTION Public education Chlorination of swimming pools and public water supplies In high-risk areas, monitoring of recreational waters for N. fowleri amoebae should be considered by local public health authorities and appropriate warnings posted, particularly during the hot summer months. Health education Avoid swimming in stagnant water Use of proper contact lens fluid

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