Entamoeba polecki

Entamoeba polecki are rarely seen in human infections in the United States and when seen it is usually in Asians. It is commonly mistaken for Entamoeba histolytica due to their morphologic similarities.

Disease / Pathogenesis

Entamoeba polecki is best known for infections in pigs and monkeys. Other farm animals can be a source. Human infections however have been recorded in individuals, especially if in close contact with swine in farms. Can be often misdiagnosed as E. histolytica. Many infections are asymptomatic. WShen synmpotoms arise they include diarrhea, bloody stools, fecer, nausea, vomiting, abdominal cramps, weight loss.

Location in the Host

Entamoeba polecki is generally the location in the host is lumen of the colon and the cecum.

Geographic Location

Entamoeba polecki is found in Southeast Asian countries which seem to have the highest concentration along with Papua New Guinea.  Pigs and other farm animals can act as a reservoir.


No vector. Transmission is via ingestion of cysts.

Life Cycle

Image courtesy of the CDC

Morphology & Diagnosis

Entamoeba polecki trophozoites and/or cysts in stool are diagnostic. Trophs are 10-20 um. A nucleus with a small karyosomw is visisble and is either seen evenly distributed or massed at one or bothe poles.  Vacuoles in the cytoplasm show ingested bacteria and yeast. Peripheral chromatin is seen as distributed granules on the nuclear membrane. They are not usually described as uniformily distributed.

Cysts are 9.5-17.5 um and spherical or subspherical. Uninuclear with abundant chromatoid material (angular – pointed – or threadlike). Glycogen vacuoles and spherical or ovoid shaped inclusion masses can be seen. Peripheral chromatin is distributed non-uniformly.


Entamoeba polecki cyst – usually only one nucleus seen, occasionally two. Chromatoid bodies of different shapes are common in the cytoplasm. Photo courtesy of CDC/ R.K. Carver
Entamoeba polecki cyst – photo courtesy of CDC/ Dr. Mae Melvin