Life-Cycle of Entamoeba histolytica

Quadrinucleated cysts (Infective stages)

Contamination of food & H2O

Excystation in Small / large Intestine

4 Metacyclic Forms (Amoebules)

Life-Cycle of Entamoeba histolytica

Amoebules in Intestinal lumen

Binary Fission 8 Amoebae

Invade intestinal tissues (Trophozoites)

Asexual reproduction by binary fission(Colonies of Amoebae:Increase in Population)

Life-Cycle of Entamoeba histolytica

Asexual reproduction by binary fission ( Increase in Population)

Last generation before encystment:Precystic stage Trophozoites Round up, Expel food particles

Encystment & Cysts in lumen

Cysts in faeces Environmental contamination (Soil/Ground) (PP : Man- 4days;Dogs-8-10Days)

Pathogenesis of E. histolytica

Attributed to Invasive natureInvasion of tissues : (?) Secretion of proteolytic enzymes Phosphohydrolase Viruses : Icosahedral & Filamentous Bacteria

Pathogenesis of E. histolytica

Invasion of Intestinal mucosa

Multiply asexually: Binary fission

Invasion in deeper layers (Submucosa)

Spread laterally

Flask shaped ulcers:Caecum & Ascending Colon

Pathogenesis of E. histolytica

Pathogenesis of E. histolytica

Flask Shaped Ulcers in Colon

Pathogenesis of E. histolytica Invasion in intestinal mucosa/submucosa

Spread to other organs via circulation

Right lobe of liver via portal circulation

Trapped in interlobular venules

Lytic necrosis Hepatic Amoebic Abscess Other organs : Lungs & Brain

Hepatic Amoebic Abscess

Pathogenesis of E. histolytica

Chronology : Sequence of events

Noninvasive colonization in Int. lumen

Invasion in Int. mucosa / submucosa ( Flask shaped ulcers)

Extraintestinal invasion: Liver/Lung/Brain

Pathogenesis of E. histolytica in Animals ( Dogs & Cats)

Dogs :Natural infections Source: Man Intestinal Disease : Caecum

Cats : Highly susceptible Acute Disease : Ulcerative lesions Organisms Fail to encyst Cat Borne Infection ?

Clinical Signs of Amoebic Dysentery

Influenced by severity of infection : Acute Amoebiosis : Severe dysentery Dehydration (Anorexia) Blood & Mucus in faeces Intense griping pain,frequently visits latrines straining blood & mucus

Prolapse of rectum

Clinical Signs of Amoebic Dysentery

Chronic Amoebiosis : Recurrent GI symptoms Viz. Diarrhoea or Dysentery Abdominal Pain (Abdominal discomfort) Nausea Flatulence Anorexia

Clinical Signs of Amoebic DysenteryExtra intestinal Phase

Liver : Pain on right side of abdomen Enlarged tender liver Fever, Vomiting, Anorexia.

Lungs : Chest Pain & Respiratory Distress.

CNS : Epilepsy & Nervous signs.

Epidemiology of Amoebiosis. Zooanthroponosis Ubiquitous : Common in tropical &

subtropical countries India; Densely populated cities Delhi- 20%; Kolkata- 24%; Mumbai- 27% & Chennai-37%. (Survey 1972)

Epidemiology of Amoebiosis

Longevity of Cysts Tetranucleated cysts: Infective stages Survive for two weeks in wet surrounding. No effect of water chlorination- viable for

several weeks Very susceptible to desiccation Thermal death point – 500C

Epidemiology of Amoebiosis Other Vital Factors : Flies

Vegetables

Food Handlers

Faulty Plumbing (Metropolitan Cities)

Epidemiology of Amoebiosis

Human & Cats suffer more severely Human Beings : Travelers disease Complete elimination is difficult &

relapses are common Cats : Organisms do not encyst

Diagnosis of Amoebiosis

Intestinal Disease Stool Sample Examination

Demonstration of cysts (tetranucleated). Differential diagnosis(1% Lugols Iodine) Trophozoites in loose stools. Immunodiagnosis: Invasive disease

Diagnosis of Amoebiosis

Intestinal Disease: SSE : Cysts

DD : Entamoeba coli

Diagnosis of Amoebiosis Extraintestinal Disease: Immunodiagnosis

Radiology

MRI

CT scan

Diagnosis of Amoebiosis

Extraintestinal Disease:

Treatment of Amoebiosis

Intestinal Disease: Metronidazole: Drug of choice. Acute : 800mg tid for 5 days. Chronic : 400mg tid for 5 days.

Treatment of Amoebiosis Extraintestinal disease: Tinidazole- 200mg bid - 5 days. Chloroquine: 150 mg bid - 10 days. Diloxanide furoate-500mg tid-10 days. Di-iodohydroxyquinoline-600mg bid-21 days Supportive : Gut acting antibiotics Anticoagulants, Astringents.

Control of Amoebiosis

Good Sanitation.

Proper sewage system.

Avoidance of contamination of food & H2O.

Health Education & Personal Hygiene.