Lab diagnosis of
Entamoeba histolytica
Entamoeba histolytica is a protozoan that causes intestinal amebiasis as well as extra-intestinal manifestations. Although 90 percent of E. histolytica infections are asymptomatic, nearly 50 million people become symptomatic, with about 100,000 deaths yearly.
2. SPECIMEN COLLECTION:
Demonstration of E.
histolytica in the material
obtained from any particular
lesion, such as
● Stool
● 'Pus' from hepatic abscess
cases
● Sputum
4. ● In acute amoebic dysentery, stool or colonic scrapings
from ulcers are examined by naked eye and microscopic
examination.
Stool examination:
5. ● Normal saline preparation is
useful for the demonstration of
actively motile trophozoites
● Iodine preparation is required for
the study of cysts or dead
trophozoites.
● Excretion of cysts in the stool is
often intermittent, therefore, at
least three consecutive
specimens should be examined.
6. ● Charcot-Leyden crystals may
appear in saline preparation.
● These are
❖ Diamond-shaped
crystals
❖ Clear
❖ Refractile.
11. ● In early cases it is always negative.
● Antibody can be detected in later
stages of invasive intestinal
amoebiasis.
● Serological tests used are
○ Indirect haemagglutination
assay (IHA)
○ Enzyme linked
immunosorbent assay (ELISA)
Serological examination:
16. Stool examination:
● In about 15% cases of hepatic abscess, cysts of
E. histolytica may be demonstrated in the stool.
● It indicates persistent intestinal infection.
17. ● Antibody detection is of
great value in the diagnosis
of hepatic amoebiasis.
● IHA and ELISA are some
serological tests used for
diagnosis.
Serological examination:
18. IHA: Serum with antibody
titre of 1:128 is diagnostic
ELISA: E.histolytica antigen
can be detected in serum
