Parasitology Table: Protozoa

Protozoa Causative Agent

Entamoeba histolytica Subphylum: Sarcodina Superclass: Rhizopoda Class: Lobosea Order: Amoebida Family: Entamoebidae Genus: Entamoeba

Life Cycle / Transmission / Morphology MOT: MOT: *Oral-fecal, contaminated water & food  Common on day care centers, institutions (prisons, mental, home for the aged), use of night soil (vegetables), food & water handlers, mechanical vectors (flies & cockroaches), sexual intimacy (homosexuals through oral & anal sex)  venereal transmission through fecal-oral contact  direct colonic inoculation through contaminated enema equipment Isoenzymes: Phosphoglucomutase, hexokinase Cystic Stage: >10 um  infective stage cyst (1-4 nuclei)  quadrinucleate cyst (1-4 – resistant to gastric acidity & dessication & can survive in a moist environment for several weeks  central karyosome – “bull’s eye karyosome  chromatoidal bodies with rounded ends (cigar-shaped)  excystation occurs in the SI or LI, where a cyst undergoes nuclear followed by a cytoplasmic division to form 8 trophozoites Trophozoite Stage: pseudopodium-long finger-like motility  cystoplasm with ingested RBCs  1 nucleus with central karyosome 

Cyst-cytoplasmic division carrying 1 nucleus on the distal SI »moves to the colon with the undigested food »descending colon (dry env’t: trophozoites do not survive) »starts to vomit out what ingested »precystic stage »trophozoites passed out in stool

Signs & Symptoms / Pathology

Diagnosis

PROTOZOAN INFECTIONS: INTESTINAL AMOEBAE only member of the family to cause colitis Microscopic detection of & liver abscess cysts & trophozoites on stool specimens  Amoebiasis  Asymptomatic: cyst passers / cyst  Consistency / carrier state (but can infect others) appearance:  Symptomatic: trophozoites   Cyst (solid)  Diarrhea/dysentery   Trophozoites (solid) – die within 30 mins to  Ulceration (intestinal) 1 hour  Extraintestinal: liver (common), lungs, brain, pericardium (serious case), skin -examine ASAP Factors:  Virulence Factors:  Contamination: urine & chlorine water may kill   lectin for adherence the trophozoite   secretion of proteolytic enzymes DFS – 2mg stool   release of cytotoxins   contact dependent cytolysis  Best method in the recovery of trophozoites   phagocytosis & cysts   symbiosis of intestinal bacteria Concentration  Host Factors: techniques   Nutrition: ꜛCHO, ꜛcholesterol diet (more favourable for colonization)  FECT (Formaline Ether Concentration Test)   Stress   Bacterial flora  MIFC (Merthiolate Iodine Formaline   ꜜ O2 tension (grows at the cecal region) CM: Concentration Test) Diarrhea – mucous  Zinc Sulfate Dysentery – mucous & blood  More sensitive than DFS in the detection of cysts   Loose bloody stools Culture   Pain & cramps on abdomen Stained smears   Fever, tenesmus, wt loss, nausea, anorexia  Gold standard Intestinal ulcer microscopically   Wide base with “bottle neck” ulcer  H&E, PAS, Trichome staining & Chlokasol   Deeper ulcer: intestinal perforation Liver/Amoebic abscess (R abscess (R lobe usu Blackez Staining (?) affected) Charcot Leyden Crystals –by-products of IgE   ALA (amoebic liver abscess) Aspirates – liver/   R hypochondriac pain, fever, jaundice, leucocytosis pulmonary (wet-stained smears)   ꜛESR, ꜛalkaline phosphates Pleuro-pulmonary amoebiasis Serology   Rupture of liver abscess at the R  IHAT (Indirect hemidiaphragm, cough, pleuritic pain, Hemagglutination) dyspnea, chills/fever, leucocytosis  IFAT (Indirect Pericarditis – rupture of the liver abscess Flourescent Atb Test) at the L lobe.  CIE (Counter Rare. If occurs, serious complication Immunoelectrophoresis)     Chest pains, CHF-like manifestation  Atg detection (Stools): Brain Amoebiasis – hematogenous route ELISA Cutaneous amoebiasis PCR  (Polymerase  (Polymerase Chain Reaction) 

Treatment

Goals:  To cure invasive disease at both intestinal & extraintestinal sites  To eliminates the passage of cysts from the intestinal lumen

Prevention & Control 

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Cyst passers  Metronidazole  Diloxanide furoate Colitis  Metronidazole  Tiridazole Liver abscess  Tiridazole Percutaneous drainage of liver abscess  To those who do not respond to metronidazole & for prompt treatment of severe pain

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Environmental sanitation Proper waste disposal Safe drinking water & food Proper food handling Hygiene Avoid night soil for fertilizer Health education & promotion

Epidemiology / Demographics Worldwide Prevalent in tropics Risks: Risks:  children, pregnant women & women in postpartum period  treated with corticosteroids, malignancy & malnutrition  

COMMENSAL AMOEBA Causative Agent Entamoeba coli

Life Cycle / Transmission / Morphology Cyst: >10 um bigger than the E. hystolitica  1-8 nuclei  Karyosome off center / eccentric  Chromatoidal bars: jagged-ends “broomsticks-” or “needle sticks-” or “slinter-” like 

Entamoeba hartmanii

Entamoeba dispar Entamoeba polecki 

Entamoeba gingivalis

Trophozoites:  Blunt / rounded & broader ps eudopodia  Slow motility (sluggish)  Thick, irregular, peripheral chromatin  Nucleus: large eccentric karyosome  No RBC on the cytoplasm but with vac uolated filling or granular endoplasm of undigested food, bacteria, etc.  Narrower, less differentiated ectoplasm Cyst: