Entamoeba histolytica is an anaerobic parasitic protozoan, part of the genus Entamoeba. Predominantly infecting humans and other primates, E. histolytica is estimated to infect about 50 million people worldwide. Previously, it was thought that 10% of the world population was infected, but these figures predate the recognition that at least 90% of these infections were due to a second species, E. dispar. Mammals such as dogs and cats can become infected transiently, but are not thought to contribute significantly to transmission.
Amebiasis is a disease caused by a one-celled parasite called Entamoeba histolytica.
Although anyone can have this disease, it is more common in people who live in tropical areas with poor sanitary conditions. In the United States, amebiasis is most common in:
E. histolytica infection can occur when a person:
Only about 10% to 20% of people who are infected with E. histolytica become sick from the infection. The symptoms are often quite mild and can include loose feces (poop), stomach pain, and stomach cramping. Amebic dysentery is a severe form of amebiasis associated with stomach pain, bloody stools , and fever. Rarely, E. histolytica invades the liver and forms an abscess (a collection of pus). In a small number of instances, it has been shown to spread to other parts of the body, such as the lungs or brain, but this is very uncommon.
Only about 10% to 20% of people who are infected with E. histolytica become sick from the infection. Those people who do become sick usually develop symptoms within 2 to 4 weeks, though it can sometimes take longer.
See your health care provider.
Your health care provider will ask you to submit fecal samples. Because E. histolytica is not always found in every stool sample, you may be asked to submit several stool samples from several different days.
Diagnosis of amebiasis can be very difficult. One problem is that other parasites and cells can look very similar to E. histolytica when seen under a microscope. Therefore, sometimes people are told that they are infected with E. histolytica even though they are not. Entamoeba histolytica and another ameba, Entamoeba dispar, which is about 10 times more common, look the same when seen under a microscope. Unlike infection with E. histolytica, which sometimes makes people sick, infection with E. dispar does not make people sick and therefore does not need to be treated.
If you have been told that you are infected with E. histolytica but you are feeling fine, you might be infected with E. dispar instead. Unfortunately, most laboratories do not yet have the tests that can tell whether a person is infected with E. histolytica or with E. dispar. Until these tests become more widely available, it usually is best to assume that the parasite is E. histolytica.
A blood test is also available but is only recommended when your health care provider thinks that your infection may have spread beyond the intestine (gut) to some other organ of your body, such as the liver. However, this blood test may not be helpful in diagnosing your current illness because the test can be positive if you had amebiasis in the past, even if you are no longer infected now.
Several antibiotics are available to treat amebiasis. Treatment must be prescribed by a physician. You will be treated with only one antibiotic if your E. histolytica infection has not made you sick. You probably will be treated with two antibiotics (first one and then the other) if your infection has made you sick.
The following items are safe to drink:
*You can also make tap water safe for drinking by filtering it through an "absolute 1 micron or less" filter and dissolving chlorine, chlorine dioxide, or iodine tablets in the filtered water. "Absolute 1 micron" filters can be found in camping/outdoor supply stores.
The following items are NOT safe to drink or eat:
Yes, but the risk of spreading infection is low if the infected person is treated with antibiotics and practices good personal hygiene. This includes thorough handwashing with soap and warm water after using the toilet, after changing diapers, and before handling food.
Several protozoan species in the genus Entamoeba colonize humans, but not all of them are associated with disease. Entamoeba histolytica is well recognized as a pathogenic ameba, associated with intestinal and extraintestinal infections. The other species are important because they may be confused with E. histolytica in diagnostic investigations.
Cysts and trophozoites are passed in feces . Cysts are typically found in formed stool, whereas trophozoites are typically found in diarrheal stool. Infection by Entamoeba histolytica occurs by ingestion of mature cysts in fecally contaminated food, water, or hands. Excystation occurs in the small intestine and trophozoites are released, which migrate to the large intestine. The trophozoites multiply by binary fission and produce cysts , and both stages are passed in the feces . Because of the protection conferred by their walls, the cysts can survive days to weeks in the external environment and are responsible for transmission. Trophozoites passed in the stool are rapidly destroyed once outside the body, and if ingested would not survive exposure to the gastric environment. In many cases, the trophozoites remain confined to the intestinal lumen (noninvasive infection) of individuals who are asymptomatic carriers, passing cysts in their stool. In some patients the trophozoites invade the intestinal mucosa (intestinal disease), or, through the bloodstream, extraintestinal sites such as the liver, brain, and lungs (extraintestinal disease), with resultant pathologic manifestations. It has been established that the invasive and noninvasive forms represent two separate species, respectively E. histolytica and E. dispar. These two species are morphologically indistinguishable unless E. histolytica is observed with ingested red blood cells (erythrophagocystosis). Transmission can also occur through exposure to fecal matter during sexual contact (in which case not only cysts, but also trophozoites could prove infective).
Life cycle image and information courtesy of DPDx.
For more information view the source:Center for Disease Control
Recommended Test:Full GI Panel
Recommended Product:Freedom Cleanse Restore Parasite Cleanse
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Parasitology Center, Inc. (PCI) in Scottsdale, Arizona is a research facility of parasites of the intestinal tract and organ systems.
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