Amoebiasis, explanation, symptoms, causes

About amoebiasis

1. AMOEBIASES MICROBIOLOGY By, A.GOPINATH AHS , OTAT

2. AMOEBIASES Amoebiases is an infection with the intestinal protozoa Entamoeba histolytica About 90% of infections are asymptomatic Remaining 10% produce a spectrum of clinical syndrome

3. Types INTESTINAL AMOEBIASES Mild abdominal discomfort Diarrhoea to acute fulminating dysentery EXTRAINTESTINAL AMOEBIASES Includes involvement of Liver (liver abscess),Lungs, brain, spleen ,etc...

4. MORPHOLOGY TROPHOZOITES : ✓ 18-40 μm in diameter ✓ Cytoplasm – outer clear ectoplasm - inner granular endoplasm - food vacuoles with RBC’s , Leukocytes and tissue debris ✓ Motile by pseudopodia extension ✓ Nucleus with central karyosome,surrounded by delicate membrane lined with chromatin granules ✓ Non infectious

5. MORPHOLOGY PRECYST : ✓ Intermediate form ✓ Oval with blunt pseudopodia ✓ no food vacuoles CYSTS : ✓ Spherical in shape , 10-15 μm in diameter ✓ Uninucleate ,later bi or quadra nucleated ✓ Thick chitinous wall ✓ Chromidial or chromatiod bars ✓ Infectious

6. PATHOGENESIS The organisms enter the gut through food and water contaminated with cyst. In small bowl hatching of cyst result into large number of trophozytes which reached to colon where “Flask Shaped Ulcer” form in the submucosa. The trophozytes multiply, ultimately forming cyst which enter the portal circulation reach to liver, where they multiply in portal triad causing focal infarction of hepatocytes and liquificative necrosis (liver abscess), and also passed in the faces as an infective form that infect other humane being as result of unsanitary conditions. INCUBATION PERIOD: 2 – 4 weeks

7. STAGES OF LIFE CYCLE Involves three stages: the cyst stage , Excyand the trophozoite stage. 1. Cyst Stage:
Infection occurs by ingestion of mature cysts through fecally contaminated water or food. Due to protection from walls, cysts survive several days and sometimes weeks. They are responsible for transmission

8. STAGES OF LIFE CYCLE 2. Excystation stage : Excystation is the process by which cysts transform into trophozoites . When the cysts enter the ileum of the small intestine of the host, the process of excystation begins. Trophozoites are released in the small intestine and from here they migrate to the large intestine.

9. STAGES OF LIFE CYCLE Tropozoite stage: Trophozoites are unicellular parasites that measure from 14 to 18 mm in diameter. They multiply in the small intestine by binary fission to produce cysts that exit via human stool. Several trophozoites remain inside the lumen of the small intestine. The rest attach themselves to the intestinal mucosa, enter the bloodstream and further grow in the extraintestinal regions of the host like lungs, liver, brain.

10. LIFE CYCLE

11. MODE OF TRANSMISSION ✓ Faeco -oral route ✓ Contaminated water and food ✓ Direct hand to mouth(cysts under finger nails) ✓ Vegetables irrigated with sewage polluted water ✓ Agency of flies, cockroaches, rats, etc.

12. CLINICAL MANIFESTATIONS ✓ Most of the cases are asymptomatic .Mild symptoms can be seen. ✓ Include Cramping and Diarrhoea ✓ Bloody stools ,fever and rarely, liver abscess may in sever cases ✓ It can invade pulmonary, cardiac, cerebral, renal and genitourinary sites in severe cases

13. LAB DIAGNOSIS Samples: 1. Stool (3 consecutive samples)
II. Biopsy material from the ulcers (colonoscopy or sigmoidoscopy)
III. Aspirate from liver abscess
IV. Serum
V. Pleural fluid
VI. Pericardial fluid
VII. Sputum

14. LAB DIAGNOSIS MICROSCOPY : Both saline and iodine wet mounts are prepared

Any motile trophozoite is better seen in saline mount lodine mount stains the internal structures and is used to identify cysts

Charcot- leyden crystals can be seen

Permanent stains can also be used to stain smears

15. LAB DIAGNOSIS • For amoebic liver abscess and other metastatic lesions- I. Radiological examination

II. Radio isotope tracing of liver

III. Ultrasonogrphy of upper abdomen

IV. CT and MRI abdomen

16. LAB DIAGNOSIS Antibody detection 1.ELISA 2. Indirect heamagluttination (IHA) 3. Immunofluorescence (IFA) Antigen detection 1. Coaguttination 2. ELISA SEROLOGY -

17. PREVENTION