In amebic dysentery (synonyms: Amebiasis, amebic dysentery; acute amebic dysentery, acute amebiasis; amebic liver abscess; amebic abscess; amebic hepatitis; ICD-10-GM A06.-: Amebiasis) is an infectious disease that primarily affects the colon (large intestine) of humans (infectious diarrhea). It is caused by the parasite Entamoeba histolytica (sensu stricto). Entamoeba histolytica (synonym: Ruhramöbe) is the only species in the Entamoeba genus that is pathogenic (disease-causing) to humans. Within the protozoa (single-celled organisms), it belongs to the rhizopods (root-feet). Furthermore, infections with the pathogens Entamoeba dispar and Entamoeba Moshkovskii occur. They account for about 90% of cases. E. dispar are also called commensals, which means they live in coexistence with the host and have no pathogenic (disease) significance. E. Moshkovskii are facultative (possible) pathogens. Naegleria fowleri is a common amoeba species in the United States that causes primary amebic meningoencephalitis (PAM). The pathogen reservoir is humans. Without causing symptoms, E. histolytica amoebae can remain in the colon for years. The so-called minuta form of the cysts can also be excreted in the stool. In the outside world, the cysts can remain infectious for many months. They are sensitive to desiccation and heating. Occurrence: The pathogen is distributed worldwide. The infection frequently occurs in the tropics and subtropics, e.g. in Kenya, India, Vietnam, Thailand, Indonesia and Bangladesh, where poor hygienic conditions prevail. Transmission of the pathogen (route of infection) is fecal-oral (infections in which pathogens excreted in feces (fecal) are ingested via the mouth (oral), e.g., through contaminated drinking water, but also contaminated food such as unwashed fruits and vegetables). Another possible route of infection is anal-oral sexual practices. Human-to-human transmission: Yes
Amoebic dysentery is divided into the following forms:
- Intestinal form (affecting the intestine) – amebic dysentery (synonyms: acute amebic dysentery; acute amebiasis; ICD-10-GM A06.0: acute amebic dysentery); marked ulcerative (ulcer-forming) colitis (inflammation of the large intestine).
- Extraintestinal form (outside the intestine) – amebic abscess (synonyms: Amoebic liver abscess; amoebic hepatitis; ICD-10-GM A06.4: liver abscess caused by amoebae); because the liver is affected by abscess formation in about 95%, this form is also often titled as amoebic liver abscess; predominantly the right lobe of the liver is affected.
The incubation period (time from infection to onset of disease) of amebic dysentery (intestinal form) is usually a few days to several weeks/months. The incubation period of amoebic liver abscess (extraintestinal form) is months to years. It is estimated that approximately 10% of the world’s population is infected with E. dispar or E. histolytica – more commonly with E. dispar. Along with malaria and schistosomiasis (worm disease), amoebic dysentery is one of the most important parasitoses in tropical and subtropical regions of the world. The duration of the disease is untreated up to several months. Course and prognosis: In most cases (approx. 90%) there is an infection with the pathogens E. dispar and E. Moshkovskii. Infected individuals excrete the parasite in the stool without developing signs of illness. In the course of infection with E. histolytica, the parasite leaves the intestinal lumen and invades the tissues (intestinal form). In severe cases, 50 bowel movements per day may occur. In any diarrheal illness, fluid and electrolyte losses must be compensated promptly to prevent dehydration (dehydration) and shift in acid-base balance. Furthermore, the parasite can spread hematogenously (through the bloodstream) to other organs. The liver is predominantly affected (amoebic liver abscess; extraintestinal form). If the disease is recognized and treated in time, it heals quickly. If an amoebic liver abscess has already formed, the medication must be taken over a longer period of time. Approximately 100,000 people die of amoebic dysentery every year (worldwide). Vaccination: A protective vaccination against amoebic dysentery is not yet available. Both infected persons and excretors are not allowed to work again in food establishments and drinking water supply systems until a further spread of the infection can be ruled out. For this purpose, three stool examinations should be carried out at intervals of one week after the end of the therapy. There is no obligation to report individual cases in Germany.Where appropriate, in the occurrence of two or more cases where a relationship is likely or suspected.
