2. CONTENTS
• INTRODUCTION
• Life cycle of Amebiasis
• Symptoms
• Diagnostic Methods
• Advance Diagnostic
• Future Direction
3. Amebiasis
• is an infection caused by any of the amobae of the Entamoeba group
• Amoebiasis, also known amoebic dysentery
• Amoebiasis is a parasitic infection due to the intestinal protozoa Entamoeba
histolytica
• Entamoeba histolytica was first described by Losch after being isolated in Russia
from a patient with dysenteric stools
• Amoebiasis is the second leading cause of death from parasitic disease
worldwide.It has been estimated that E. histolytica infection kills more than
100,000 people each year
• Secreting proteinases that dissolve host tissues, killing host cells on contact, and
engulfing red blood cells, E histolytica trophozoites invade the intestinal mucosa,
causing amoebic colitis
• It can affect anyone, although it is more common in people who live in tropical
areas with poor sanitary conditions
5. Symptoms
• A change in the sense of smell or taste
• Fever
• Sudden, severe headache
• Stiff neck
• Sensitivity to light
• Nausea and vomiting
• Confusion
• Loss of balance
• Sleepiness
• Seizures
• Hallucination
6. Diagnostic Methods
• Ova and parasite examination
• Body Aspirates
• Immunodetection(Advanced method)
• Histology
7. Ova and parasite examination
• Microscopic examination of a direct saline wet mount may reveal motile
trophozoites, which may contain RBCs
• the most important technique for the recovery and identification of protozoan
organisms is the permanent stained smear (normally stained with trichrome or iron
hematoxylin)
• A minimum of three specimens collected over a time frame of not more than 10
days is recommended
• If slides are prepared properly and examined carefully, sigmoidoscopy specimens
may be very helpful
9. Body Aspirates
• liver abscess can be achieved by identification of organisms from liver aspirate material
• However, this procedure is rarely performed, and often the specimen obtained is not
collected properly
• Aspirated material must be aliquoted into several different containers as it is removed
from the abscess; amebae may be found only in the last portion of the aspirated material
10. Immunodetection
• A number of enzyme immunoassay reagents are commercially available, and their
specificity and sensitivity provide excellent options for the clinical laboratory
• The majority of these procedures use the enzyme-linked immunosorbent assay (ELISA) or
enzyme immunoassay (EIA) formats
• Another product is available as a cartridge format that uses an immunochromatographic
strip-based detection system for the E. histolytica /E. dispar group, Giardia lamblia, and
Cryptosporidium spp
11. Enzyme Link Immunosorbent Assay(ELISA)
• Enzyme-linked immunosorbent assay (ELISA) is used to detect antigens from E
histolytica in stool samples. Several kits are commercially available
• Antigen-based ELISA kits using monoclonal antibodies against the galactose/N -
acetylgalactosamine (GAL/GalNAc)–specific lectin of E histolytica yield an overall
sensitivity of 71-100% and a specificity of 93-100%
• In patients with amebic liver abscess, serum and liver aspirate antigen detection
using the same kit was shown to yield a sensitivity of 96% in serum and 100% in
liver aspirate.
12.
13. Antibody detection
• Serologic testing for intestinal disease is normally not recommended unless the patient
has true dysentery; even in these cases, the titer (indirect hemagglutination as an
example) may be low and thus difficult to interpret.
• For patients suspected of having extraintestinal disease, serologic tests are much more
relevant
• Recombinant human monoclonal antibody Fab fragments specific for E. histolytica have
also been developed
• These antibodies may be applicable for distinguishing E.histolytica from E. dispar and for
use in the serodiagnosis of amebiasis
14. Histology
• A histologic diagnosis of amebiasis can be made when the trophozoites within the tissue
are identified
• Organisms must be differentiated from host cells, particularly histiocytes and ganglion
cells
• Periodic acid-Schiff staining is often used to help locate the organisms
• The organisms appear bright pink with a green-blue background (depending on the
counterstain used)
• Hematoxylin and eosin staining also allows the typical morphology to be seen, thus
allowing accurate identification
16. FUTURE DIRECTION
• Although considered a neglected disease, research on amebiasis continued
unabated
• Progress on research in amebiasis encompassed studying the life cycle stages and
biology of E. histolytica, use of modern tools of genomics and metabolomics to
analyze the responses of the parasite to different host stimuli and involvement of
chemistry to develop new drug leads to control the parasite
• Advances in molecular epidemiology and pathogenesis have advanced our
understanding of this parasite; however,many gaps in knowledge remain
• In addition, although efforts are ongoing, there is no vaccine and only a single
effective drug class.
