amebiasis is caused by what Flashcards
amebiasis is caused by what
entamoeba hystolicica
Brumpt 1949, proposed to establish a new species of ….. to designate the
amoebae that are not pathogenic
Entamoeba
In 1993, it was decided that the invasive form will be called …..
E. histolytica.
The non-invasive form of entamoeba will be called
E dispar
true or false, we can distinguish both entamoeba under the microscopy
false
what are the non pathogenic entamoeba
Entamoeba hartmani
Entamoeba dispar
Entamoeba coli
what is the three most common parasitic cause of death
entamoaba hystolitica
-70-100 000 per year
how many people are infected with entamoeba hysto
500 million
true or false: entamoeba hysto is waterborne
true
§ Water, food
§ Flies can act as passive vectors
§ Can be sexually transmitted
§ Person-to-person contacts
where is entamoeba found
Mexico, Central & South America, Africa, South Asia
true or false: humans are the only source for entamoeba
true
what is the transmission for entamoeba
fecal and oral
what are the 4 things about amebiasis
1) asymptomatic carrier state
2) acute amoebic dysentery
3) amoebic liver abscess
4) amoeboma
presence in the world E. histolytica/dispar
developing countries is ~10% E. histolytica;
developed countries is ~1% E. histolytica
the infective dose of entamoeba can be as little as
1 cyst
what is the incubation period entamoe
few days to few weeks depending on dpse
true or false: entamoeba cysts can survive for weeks at appropriate temperatire and humudity
true
cytoplasmic structures entamoeba
-nucleus: the inner surface membrane is line with periferal chronation, you get like 1-4 lil rings
-endosome: located in the center of the nucleus and they contain dna
-vacuoles: They occupy a great proportion of the
cytoplasm. They vary between 5 to 9µ
in size.
what are vacuoles important for in entamoeba
They may contain cellular debris, red blood
cells, bacteria - feeding
Amoeba cells can live and multiply indefinitely within the
crypts of the mucosa of the…..
large intestine
true or false: entamoeba are able to invade the mucus later
true
it constitutes a major non specific defense mechanism
what do entamoeba feed on
They feed on starches and mucous secretions and interacting metabolically
with enteric bacteria.
entamoeba initiate tissue invasion when they……
-they hydrolyse mucosal cells and absorb the
pre-digested products.
-At this stage they no longer need to feed on bacteria.
Tiny cytoplasmic extensions from the surface of trophozoites called …
filopodia
Tiny cytoplasmic extensions from the surface of trophozoites called filopodia may have the following functions related to
pathogenesis:
- Endocytosis
- Attachment to substrate
- Penetration of tissue
- Release of cytotoxic materials
- Cytolysis of cells
presentation of entamoeba
- Diarrhea to dysentery with bloody and mucous
- Fever
- Abdominal pain
diagnosis entamoeba
- Amoebic (hematophagous trophozoites and cysts) in stool
- Patchy inflammation seen on colonoscopy
- Serology – antibodies in serum
- Stool PCR - detection of parasite DNA in stool
- Antigen capture – detection of parasite protein in stool
pathology entamoeba: intestine
-Remarkable and unique ability to hydrolyze host tissues with their active proteases present on the surface membrane of the trophozoite.
-Lesions are found in the caecum, appendix, or colon. They may heal.
-If perforation of the colon occurs, there is peritonitis that can lead to death.
Amoeboma - Granuloma obstructing the …
bowel
Hepatic amebiasis occurs
when trophozoites enter t…
mesenteric veinule and travel
to the liver through the
hepatic portal system.
Only about 5-10% of
infections will affect …. for entamoeba
the liver.
treatment entamoeba:
Metronidazole or tinidazole, followed by iodoquinol or paromomycin
mechanism of cytotoxicity entamoeba
- Direct contacts with the host tissues
- Release of soluble toxic metabolites
- High enzymatic activities of the amoebas
- Interfering with the immune response of the host.
entamoeba: Direct contacts with the host tissues.
adherence to the host cell by the release of adhesin
molecules.
entamoeba: Release of soluble toxic metabolites.
amoebapore are capable of forming a hole in a target cell.
The immune system can kill the amoebic cell: how
-macrophages
-cytotoxic cd8t cells
-antibodies don’t do much
Macrophages activated by cytokines can kill Entamoeba trophozoites. The killing mechanism is contact-dependent and is mediated by both…..
oxygen and oxygen independant mechanisms
True or false: Antibody-dependent cell-mediated-cytotoxicity is not an active mechanism to kill entamoeba.
true
Lysis of amoebas has not been observed with either immune serum alone or with complement. Therefore, …
Th2 type of immune response is not playing a major role against amoebiasis
amebiasis of the skin
- This infection arises by direct spread of a primary abscess.
- This patient was erroneously
operated for a perforated duodenal
ulcer and no anti-amoebic drugs were
given.