What is it about ?
An amoeba is a microorganism made up of a single cell. It can live freely or as a parasite. Amebiasis is an infection with an amoeba.
Entamoeba histolytica is an amoeba which can infect humans. Contamination can be done in two ways:
- by direct contact with the stool of an infected person,
- by indirect contact with the stools of an infected person, usually by drinking water or eating food contaminated with these stools, for example by fertilization with contaminated manure or by a poor sewage system.
When a person takes in contaminated food or water, the ingested cysts develop into amoebae. Entamoeba histolytica can survive in the large intestine. It produces cysts which are eliminated with the stool. In turn, these stools containing cysts can infect other people.
The incubation period, that is to say the time between the consumption of cysts and the disease, is very variable: 1 week to 4 months.
Amoeba can cause diarrhea. They can damage the intestinal wall, causing blood in the stool (amoebic dysentery). They are able to penetrate the wall of the intestine, invade the envelope that surrounds the intestines (the peritoneum) and cause peritonitis. They can pass into the bloodstream and end up in the liver, where they are responsible for forming an abscess .
Amebiasis can lead to death, in particular by the formation of an abscess in the liver, but also following diarrhea (bloody). This usually happens in people who live in poor sanitary conditions and have limited access to care.
Where, in whom and how often does it occur?
E. histolytica is present all over the world, but especially in the tropics and subtropics where sanitary conditions are poorer. Immigrants or travelers from these regions are among the groups at risk.
Around the world, roughly 1 in 10 people would be infected. Every year, 40 to 50 million people are infected. Out of 1000 infected people,
- 100 people develop amoebic dysentery,
- the infection spreads to the liver in less than 10 people,
- 1 to 2 people die, usually from the development of an amoebic abscess.
How to recognize it?
Most infected people develop few or no symptoms. If the amoeba gets into the intestine, it can cause diarrhea . The diarrhea can be mild (loose stools) or severe (bloody stools and severe stomach pain). There may also be stomach aches, cramps, moderate fever, and headaches .
Signs of an amoebic abscess can be fever, stomach ache (especially in the upper right stomach), nausea, or weight loss.
How is the diagnosis made?
The physician should consider the possibility of an amoebic abscess when his patient suddenly develops a high fever with chills within 5 months of returning from (sub) tropical regions, in addition to a general feeling of malaise and pain in the upper abdomen on the right or in the flank. Sometimes a slower course is observed with periods of rising temperature, feeling unwell, and weight loss. The upper abdomen is sensitive to pressure during physical examination and the doctor may feel swelling of the liver.
Blood tests show, among other things, an increased number of white blood cells, disturbances in liver enzymes, inflammatory parameters and antibodies against E. histolytica. Ultrasound of the liver can confirm the presence of an abscess. Examination of a stool sample will help prove the presence of amoebae in the intestines. If there is any doubt as to the cause of the infection (eg insufficient response to drugs), puncture of the abscess may be indicated; the collected liquid is then sent for further examinations.
What can you do ?
To avoid catching amebiasis, use plain water. Treat impure water with iodine tablets in a good filtration system, or heat it over 50 ° C for more than 5 minutes. The cysts will then be destroyed, allowing you to drink the water safely. Chlorine added to drinking water does not destroy cysts.
The classic advice for food also holds true here: “boil it, cook it, peel it or forget it”. When you go on vacation, learn about disease prevention . A reliable source is the website of the Institute of Tropical Medicine .
Après un séjour à l’étranger, si vous souffrez de maux de ventre, de diarrhée sévère et/ou sanguinolente et de fièvre, vous devez en informer votre médecin et lui dire dans quel pays vous vous êtes rendu.
Que peut faire votre médecin ?
Sans traitement, l’abcès amibien est mortel. Les médicaments antiparasitaires (comme le métronidazole) sont efficaces. On peut aussi envisager le drainage de l’abcès, c’est-à-dire que le spécialiste aspire l’abcès à l’aide d’une aiguille à travers la peau. D’autres médicaments sont nécessaires pour éliminer les kystes dans les intestins.