Amoebic dysentery (Amebiasis) is a tropical intestinal disease that is transmitted, for example, through contaminated drinking water or food. The symptoms depend on which form of amoebic dysentery you have. If left untreated, the amoebas spread to organs throughout the body and sometimes lead to death. Here you can read everything you need to know about amoebic dysentery.
ICD codes for amoebic dysentery disease: A06
Quick overview
• Symptoms: The symptoms differ depending on whether you are suffering from a so-called intestinal or extraintestinal amebiasis and include bloody diarrhoea, abdominal cramps, fever and pus formation in the liver.
• Treatment: Special antibiotics are available to treat amoebic dysentery.
• Causes: The parasites are transmitted fecal-orally, i.e. by ingesting cysts excreted in the stool.
• Risk factors: There is a particular risk of infection in developing countries. The risk factors include low hygiene standards, but also, for example, anal-oral intercourse.
• Diagnostics: In addition to blood and stool tests, other examination methods such as ultrasound, MRT and CT are available for diagnosis.
• Prognosis: Amoebic dysentery is considered completely curable if treated properly.
• Prevention: The probability of contracting amoebic dysentery can be reduced by appropriate hygiene measures.
What is amoebic dysentery?
Amoebic dysentery is caused by the protozoan Entamoeba histolytica. It’s not the only amoeba that affects humans, but it alone makes them sick. The amoebas that do not (E. dispar, E. moshkovskii) are much more common.
You are ten times more likely to have a non-pathogenic amoeba species than to be infected with E. histolytica.
Entamoeba histolytica and E. dispar together form the so-called “E. histolytica/E. dispar complex”. It is estimated that around half a billion people worldwide carry both types at the same time. However, the majority of these people are affected by the non-disease-causing E. dispar.
About 50 million people fall ill with amoebic dysentery every year, of which a maximum of 100,000 die as a result of the infection.
Not every infected person also falls ill with amoebic dysentery.
More than 90 percent of parasite carriers never develop symptoms. However, since they still pass propagation stages (cysts) in their stool, they are constantly infecting other people. Only when the amoebas manage to leave the intestines and enter the bloodstream do they cause life-threatening damage to other organs.
What is an amoeba?
An amoeba is a parasite that belongs to the group of protozoa and feeds mainly on red blood cells in the human body. A much better known protozoal disease is malaria. Amoebic dysentery (amebiasis) is transmitted through the cysts of the amoeba.
These spherical survival stages are much more robust than the mobile form of the amoeba and thus increase the probability of transmission. They slowly dry up outside the intestines and do not need food.
If humans eat cysts, they develop into amoebas in the small intestine and multiply. Once in the large intestine, the amoebas have two options:
They either develop into cysts and are passed out again in the stool, or they attack the intestinal wall. If they are excreted and taken in by another person, the cycle closes.
If the intestinal wall is attacked in amoebic dysentery, abdominal pain with bloody diarrhea occurs. In rare cases, the amoebas get into the bloodstream and are transported to different organs.
Due to the fight between the immune system and the amoeba, there is then a strong formation of pus within the organ. Doctors then speak of an abscess.
How do you get infected with amoebic dysentery?
Infected people constantly shed cysts. If these cysts get into drinking water or on food that is eaten raw, others may become infected from eating the contaminated food or water.
Transmission is particularly likely via:
• Fruits and raw vegetables.
• Water and drinks.
• Ice cream or sorbet.
• Salad
In general, a damp, dark environment is ideal for the cysts. In such a habitat, they survive for several weeks in drinking water or on food. Even short trips to high-risk countries are enough to become infected with amoebic dysentery. In high-risk areas, about half of the local population is infected.
Where does amoebic dysentery occur?
Amoebic dysentery is transmitted fecal-orally. This means that cysts excreted in the stool must be ingested in order to become infected.
Wherever there are no high hygiene standards, there is a risk of transmission of amoebiasis. This applies in particular to developing countries. People are often infected in Central and South America, Africa and South Asia, but infections also occur in western countries.
What are the symptoms of amoebic dysentery?
Most people infected with the amoeba E. histolytica do not show any symptoms of amoebic dysentery. A pure infection without symptoms is referred to as an infestation.
About ten percent of cases develop what is known as “ intestinal amoebiasis ”, in which the amoebas penetrate the intestinal wall and colonize it.
In only one percent of cases do the amoebas get into the bloodstream and colonize organs such as the liver. Abscesses form in these organs, which limit organ function and, in the worst case, lead to death.
If the parasites get from the intestine to other areas of the body, the doctors speak of “ extra-intestinal amebiasis ”.
Intestinal amebiasis
Intestinal amebiasis is amebic dysentery in the narrower sense. The onset of amoebic dysentery is rather insidious. One to several weeks after the infection, there are mucous, sometimes bloody diarrhea and abdominal cramps six to eight times a day.
The stool is frothy or glassy and is often described as raspberry jelly-like. Sometimes there may be constipation and severe tenderness in the lower abdomen. In addition to weight loss, fever and chills are also possible in severe cases of amoebic dysentery.
Since other diagnoses such as bacterial diarrhea or appendicitis are more common than amoebic dysentery in western countries, it is important to inform the doctor if those affected have recently traveled to the tropics.
If intestinal amebiasis is not recognized, the symptoms persist. They are easily confused with inflammatory bowel diseases such as Crohn’s disease or ulcerative colitis. Both diseases are an incorrect reaction of the immune system against the intestines, which also leads to repeated diarrhea and abdominal pain.
If misdiagnosed, there is a risk of further complications from amoebic dysentery. The inflammation may cause lumps in the intestinal wall that interfere with the passage of stool. If this is the case, the doctors speak of an intestinal obstruction (ileus).
In rare cases, the intestine may rupture, with serious consequences for the patient and his life. There is also a risk that the amoebae will get into the bloodstream and cause extraintestinal amoebiasis.
Extraintestinal amebiasis
If the amoebas get into the bloodstream, they reach almost all organs. Most often, they migrate from the intestines to the liver. This occurs months to years after infection and can occur without prior symptoms of diarrhea or regular abdominal pain.
In the liver, the amoebas form an abscess. A liver abscess due to amoebic dysentery is accompanied by high fever and severe pain under the right costal arch. Since the pain radiates, pain in the right shoulder or costal arch is also possible.
The infection sometimes breaks through from the liver to the chest and heart. Although the amoebas reach the liver via the intestines, only 30 percent of abscess patients experience diarrhea. This means: Even without abdominal pain and diarrhea, an amoeba infection is possible.
How is amoebic dysentery treated?
In the treatment of amoebic dysentery, it plays an important role whether the amoeba have already damaged the intestinal wall or whether the infestation is asymptomatic. Both require medical treatment to avoid later complications and to limit the spread of amoebic dysentery as efficiently as possible.
Infestation without symptoms:
If E. histolytica was detected in the stool without symptoms of amoebic dysentery and without evidence of organ damage, therapy with the antibiotic paromomycin is sufficient for about ten days. The substance is not absorbed into the body and thus only kills the amoebas in the intestine.
Infection of the intestinal wall (intestinal amebiasis):
If the amoebas have invaded the intestinal wall, bloody, mucous diarrhea usually occurs. If this is the case, the amoebic dysentery is treated with metronidazole in addition to paromomycin. The doctor uses a stool sample examination to check whether the treatment was successful.
Amoebic abscess:
Treatment of extraintestinal amebiasis is the same as for the intestinal form. An operation or puncture of an amoebic abscess is only carried out if the pus-filled blister threatens to burst. If the abscess is recognized in time and treated consistently, it will recede over several weeks.
In severe cases of the amoebic infection, the patient may first have to be stabilized before definitive therapy can be given. If the person concerned is seriously ill, the doctor must decide, depending on the organ and patient, how exactly to proceed in order to save the patient’s life.
Amoebic dysentery: causes and risk factors
If you look at all transmission routes of amoebic dysentery, it becomes clear that the main risk factor lies in the hygienic conditions of the respective region.
When traveling to affected regions, particular attention must be paid to the hygiene of drinking water and food. One’s own behavior in tropical and subtropical countries accounts for a large part of the risk of disease.
Another route of infection is anal-oral intercourse. Here, the cysts go directly from the rectum into the mouth of the sexual partner.
In addition, the following are also becoming increasingly ill:
• Small children.
• Elderly people.
• Pregnant women.
• Patients on cortisone therapy.
• Immunocompromised patients.
• Malnourished people.
For these people, complications such as a liver abscess are often more serious than for other patients. Early diagnosis and consistent therapy may prevent the amoeba from spreading.
Investigations and diagnosis of amoebic dysentery
If there is a suspicion of an infection, the family doctor or pediatrician is the first point of contact to have the appropriate examinations carried out. In order to diagnose amoebic dysentery, the doctor has a number of tests available.
At the beginning there is a direct conversation with the patient. Past trips to risk areas should be mentioned, as well as acute symptoms. The doctor asks the following questions:
• Have you recently been to a tropical country?
• Do you have diarrhea and if so, how long has it been?
• Is your diarrhea bloody and mucous?
Even if the stay abroad may have been years ago, it is important to inform the doctor about the trip so that he can make a suspected diagnosis of amoebic dysentery.
Amoebic dysentery is detected by means of a stool or tissue sample from the intestine (intestinal biopsy), which the doctor or laboratory technician examines under the microscope. However, it is usually not possible to distinguish between the malignant E. histolytica and other amoeba species in this way.
However, there are special methods that detect either certain components of the amoeba, so-called amoeba antigens, or the genetic information (DNA) of E. histolytica in the stool.
Blood tests are also available to check for antibodies in the blood produced by the patient’s immune system when infected with E. histolytica.
A blood test also becomes important when extraintestinal amebiasis is suspected. In the case of extraintestinal amebiasis, one does not necessarily find cysts in the stool, but only the amoebas in the affected organs.
If the mucous membrane in the intestine is damaged, the injuries can be seen in a colonoscopy. During this examination, the doctor uses a camera on a flexible rod to look at the intestinal mucosa.
If organs other than the intestines are affected, the abscess can be viewed in one image using ultrasound and, if necessary, computed tomography (CT) or magnetic resonance imaging (MRI).
The doctor does not have to report the amoebic dysentery to the health department. However, if there is an increase in cases among his patients, this must be reported.
Amoebic dysentery: course of the disease and prognosis
The forms of amoebic dysentery are very diverse. Infection with E. histolytica does not make everyone sick. Even if you get sick, the symptoms range from simple diarrhea to a life-threatening liver abscess.
In any case, a known infection should always be treated consistently to protect yourself and others. If this is the case, amoebic dysentery is now considered a completely curable disease. About 100 years ago, amoebic dysentery was a major health problem in world.
However, if amoebic dysentery is left untreated, you are contributing to the spread of the disease, and it may eventually lead to the dangerous organ damage that is potentially life-threatening.
The two drugs against amoebic dysentery are well tolerated and promise a complete cure if the disease is recognized and treated early enough.
Prevention of amoebic dysentery
In order to prevent amoebic dysentery, the following rules must be observed when traveling to risk areas:
• Peel raw fruit before eating.
• It is best to boil vegetables.
• Don’t eat raw meat or raw seafood.
• Do not drink tap water; Also, do not use it to brush your teeth without boiling it first.
• Even chlorinated water does not provide any protection. If you are unsure, always boil the water as a precaution.
• Be careful with unsealed water bottles in restaurants, as these are often refilled with tap water.
• Also avoid ice cubes or homemade water ice and sorbet.
• Use separate condoms for intercourse and oral sex.
By taking these precautions, you will reduce the likelihood of developing amoebic dysentery. If, despite all precautionary measures, you suspect that you have caught amoebic dysentery, go to the doctor immediately.
