Entamoeba
histolytica
Test code:
X0048
- Ultrasensitive qualitative detection and differentiation of
Entamoeba histolytica by real time PCR.
Entamoeba histolytica
is a single-celled, anaerobic parasitic protozoan (amoebozoan)
that primarily infects humans and other primates, causing the
disease known as amebiasis (or amoebic dysentery). This parasite
is morphologically similar to non-pathogenic species like
E. dispar, E.
moshkovskii, and E.
Bangladeshi, so that it is difficult to visually
differentiate these species.
This parasite’s life cycle consists of a trophozoite stage and a
cyst stage. Infection starts when mature cysts are ingested from
contaminated sources. In the small intestine, these excyst to
release trophozoites, which then migrate to the large intestine.
Trophozoites can multiply by binary fission. They can either
remain in the intestinal lumen causing asymptomatic infection
and cyst passage, or invade the intestinal mucosa leading to
disease. They can also spread through the bloodstream to
extraintestinal sites like the liver. Both cysts and
trophozoites are shed in feces, but only cysts can survive
outside the body for days to weeks.
Transmission of this parasite is primarily through the
fecal-oral route through ingestion of cysts in contaminated food
and water. It can also transmit through sexual contact involving
fecal exposure. The parasite is found worldwide, with higher
prevalence in developing countries where sanitation is poor.
Most infections are asymptomatic. However, some infected people
may develop invasive intestinal amebiasis (amebic colitis);
symptoms can include diarrhea (often bloody), abdominal pain,
weight loss, constipation, and dysentery. Complications include
peritonitis, perforations, amebomas (granulomas), and
extraintestinal issues like liver abscesses, pleuropulmonary
abscesses, or brain abscesses.
Microscopic identification in fecal smears has low sensitivity
and specificity. Because this parasite is morphologically
similar to other non-pathogenic
Entamoeba species,
diagnosis of E.
histolytica often requires other confirmation. Polymerase
chain reaction (PCR) is increasingly being used to diagnose this
parasitic infection due to its high specificity and sensitivity
(Blessmann et al., 2002; Kebede et al., 2004).
Utilities:
-
Help confirm the disease causing agent
-
Shorten the time required to confirm a clinical diagnosis of
Entamoeba histolytica infection
-
Help ensure that animal groups are free of Entamoeba
histolytica
-
Early prevention of spread of Entamoeba histolytica between
animals
-
Minimize human exposure to Entamoeba histolytica
References:
Blessmann J, Buss H, Nu PA, Dinh BT, Ngo QT, Van AL, Alla MD,
Jackson TF, Ravdin JI, Tannich E. Real-time PCR for detection
and differentiation of Entamoeba histolytica and Entamoeba
dispar in fecal samples. J Clin Microbiol. 2002
Dec;40(12):4413-7.
Kebede
A, Verweij JJ, Endeshaw T, Messele T, Tasew G, Petros B,
Polderman AM. The use of real-time PCR to identify Entamoeba
histolytica and E. dispar infections in prisoners and
primary-school children in Ethiopia. Ann Trop Med Parasitol.
2004 Jan;98(1):43-8.
Specimen requirement: 0.2 ml feces,
or rectal swab, or 0.2 ml soil
Contact Zoologix if advice is needed to determine an appropriate specimen type for a specific diagnostic application. For specimen types not listed here, please contact Zoologix to confirm specimen acceptability and shipping instructions.
For all specimen types, if there will be a delay in shipping, or
during very warm weather, refrigerate specimens until shipped
and ship with a cold pack unless more stringent shipping
requirements are specified. Frozen specimens should be shipped
so as to remain frozen in transit. See
shipping instructions for
more information.
Turnaround time: 2 business days
Methodology: Qualitative real time PCR
Normal range: Nondetected
