Entamoeba histolytica E. coli E. gingivalis Class Lobosea & Amebic Infections Entamoeba histolytica E. coli E. gingivalis

Class Lobosea

Intestinal Amebae Entamoeba E. histolytica (pathogen) E. coli E. gingivalis

Entamoeba Morphology Ingested RBC Nucleus with central karyosome and finely divided peripheral chromatin Pseudopod E. histolytica trophozoite

Entamoeba Morphology 1-4 ring-like nuclei with finely divided peripheral chromatin Cyst wall and round shape Mature E. histolytica Cyst

Morphologic Comparison Entamoeba histolytica Cysts Trophozoites Thick wall Plasmalemma (thin) 1-4 ring-like nuclei 1 ring-like nucleus Chromatoidals (blunt) Lacking Round, 14-20 µm Irregular, 12-17 Concentratable Labile

Life Cicle of E. histolytica Amebiasis Transmission Humans acquire E. histolytica by: Ingesting cysts in fecally contaminated food or drink Rarely by directly inoculating trophozoites into colon or other sites (anal sex?) Fecal-Oral transmission (hand to mouth) Infective cysts and trophozoites pass in feces

E. histolytica Stages - CYSTS Usual Infective Stage for humans Resistant walls maintain viability If moist can last several weeks Killed by desiccation or boiling Usual Diagnostic Stage in formed stools Can be concentrated and stained easily Not seen in liquid (diarrheic) stools or tissues

E. histolytica Stages - TROPHOZOITES Are the motile, feeding stages that: Cause amebiasis (damage tissue) Spread throughout the body, but ... rarely transmit the infection to others are labile in liquid stools or tissue, and must be rapidly found or preserved (quick fixation & cold storage) for laboratory diagnosis

Pathogenesis of Amebiasis Trophozoites ... Attach to mucosal epithelial cells (MEC) Lyse MEC Ulcerate and invade mucosa Cause dysentery (diarrhea + blood) Metastasize via blood &/or lymph Form abscesses in extraintestinal sites

Clinical Classification of Amebiasis (World Health Organization) Asymptomatic (intestinal) Amebiasis "Cyst Passers” Most common Infection may continue without clinical symptoms for weeks to months ... May spontaneously resolve (self cure)/or carrier state Symptomatic Infection: Intestinal Amebiasis: (colon and rectum) Acute Dysenteric (dysentery) Chronic Non-Dysenteric (“self-cured”) Extra-Intestinal Amebiasis: Amebic Liver Abscess (ALA) Amebic Pulmonary Abscess Other sites (brain, skin, GU, ?)

Acute Dysenteric Amebiasis: Amebic Dysentery Symptoms: Bloody mucoid diarrhea RBCs and few WBCs (pus) in stools Abdominal pain weight loss bloating, tenesmus and cramps Signs: Fever (33%) Diffuse abdominal tenderness Tender (enlarged) liver Stools positive for trophozoites +/- WBC NOT cysts in loose stools

Pathology Intestinal ulcers are due to enzymatic degradation of tissue. The infection may result in appendicitis, perforation, stricture granuloma, pseudo-polyps, liver abscess Sometimes brain, lung and spleen abscesses can also occur. Strictures and pseudo-polyps result from the host inflammatory response.

Amebic abscess of liver Gross pathology of liver containing amebic abscess Gross pathology of amebic abscess of liver.

Chronic Non-Dysenteric Amebiasis: “self-cured” carrier state 37% symptomatic >5 years Intermittent diarrhea, mucus, abdominal pain, flatulence and/or weight loss E. histolytica trophs (rarely cysts) in stools Positive serology

Intestinal Amebiasis Complications Intestinal perforation and Peritonitis (a surgical emergency) Ameboma Palpable mass of granulation tissue that may obstruct colon Toxic megacolon complication of inappropriate steroid therapy

Entamoebasis injuries of lungs perforation of diaphragm abscess in liver injury of descending colon injury of ascending colon Entamoebasis

Extra-Intestinal Amebiasis: Amebic Liver Abscess (ALA) Symptoms dysentery (1 yr), weight loss, abdominal pain, chest or shoulder pain Complications Pulmonary Abscess: by direct extension through the diaphragm into thorax Rupture into the pleural cavity and/or hepatobronchial fistulas => trophozoites in sputum! Extension to other sites, including peritoneum, pericaridum, others Amebic Pulmonary Abscess Other sites: brain, skin, urogenital system

DX: Laboratory Diagnosis of Hepatic Amebiasis Examine stools for trophs/cysts (suggestive) Blood cell counts - leukocytosis? Radiologic Studies Serologic tests Catheterize abscess and aspirate: Examine "anchovy paste" aspirate for trophozoites and do serologic testing for amebic antigens Culture for other pathogens (sterile on first stick, then contaminants) Chemotherapeutic Trial

Diagnosis of Intestinal Amebiasis Techniques: Direct Fecal Smear (trophs and cysts) Fecal concentration techniques - (cysts) Permanent Stained Fecal Smear Serologic Tests (for chronic disease)

E. histolytica: Microscopy 1 2 Entamoeba histolytica trophozoites in section of intestine Entamoeba histolytica cyst and trophozoite, haematoxylin stained

Entamoeba

Entamoeba

Prevention/Control of Amebiasis Individual measures Diagnosis and treatment of E. histolytica patients no animal reservoirs (other than humans) are known Safe drinking water (boiling or 0.22 µm filtration) Cleaning of uncooked fruits and vegetables Prevention of contamination of food

Prevention/Control of Amebiasis Community measures Public services and utilities Adequate disposal of human stools Safe and adequate water supply Primary health care systems Health education (washing hands, cleaning and protecting food, controlling insects) Specific surveillance programs and Control programs integrated into ongoing sanitation & diarrhea control Health Regulations Control of food vendors and food handlers Control of flies and cockroaches

Entamoeba coli It is a commensal of the human large intestine, but it looks much like E. histolytica Cyst usually has 8 nuclei Does not produce the protein-degrading [proteolytic] enzymes nucleus food vacuole

E. coli: Morphologic Comparison

Entamoeba gingivalis amoeba Red blood cells

Entamoeba gingivalis lives in/on the teeth, gums, and sometimes tonsils. it measures 10-35 µm in length is present in all cases of active periodontitis does not produce the cysts

Infections with Free Living Amebae Naegleria fowleri Acanthamoeba spp.

Diseases caused by F.L.A.

Free Living Amebae Not seen in humans Naegleria Acanthamoeba cysts & trophs are seen in humans

Life cycle of Naegleria fowleri 1 – cyst, 2 – amoeba makes it way into cranium, 3 – switches to flagellate in order to swim into mouth or nose.

Primary Amebic Meningoencephalitis PAM An acute suppurative infection of the brain and meninges that is rapidly fatal and usually not diagnosed antemortum Caused by Naegleria spp. Headache, lethargy and olfactory problems Sore throat, runny nose, severe headache, vomiting, stiff neck, confusion leading to ... Coma and death

Primary Amebic Meningoencephalitis PAM Thermophilic, chlorine tolerant trophozoites penetrate cribiform plate and follow olfactory nerves into brain ... Acute inflammation and hemorrhagic necrosis Sanguinopurulent exudate containing trophs is found in meninges & tissues CSF: Glucose -, Protein +, Leukocytes + NEG Gram stains and bacterial CSF cultures

Acanthamoeba spp. Acanthamoeba trophozoites with acanthopodia

Acanthamoeba are found in the soil and dust, in fresh water (lakes, rivers, and hot springs and in hot tubs. may also be found in sea water can also be found in contact lens paraphernalia Acanthamoeba have been found in the nose and throat of healthy people as well as those with compromised immune systems.

Acanthamoeba can enter the skin through a cut, wound, or through the nostrils can travel to the lungs and through the bloodstream to other parts of the body, especially the central nervous system. can enter the eye via contact lenses or through a corneal cut or sore. Infection, keratitis or a corneal ulcer results. In addition, it can cause skin lesions and/or a systemic (whole body) infection!!!

Acanthamoeba Keratitis Corneal infection with Acanthamoeba spp. trophozoites & cysts Ulcerations & “Ring Infiltrate” of cornea Induced by trauma to eye, exposure to contaminated H2O contact lens wear with tap water rinsing Cavorting in hot tub wearing soft-contacts!

Granulomatous amebic encephalitis (GAE) Acanthamoeba spp. cause a serious, most often deadly infection called GAE Symptoms: headaches, stiff neck, nausea and vomiting, tiredness, lack of attention to people and surroundings, loss of balance and bodily control, seizures, and hallucinations. Signs and symptoms progresses over several weeks and death usually occurs.