Intestinal infections are a large group of diseases that combine damage to the organs of the gastrointestinal tract and characteristic clinical manifestations in the form of nausea, vomiting, diarrhea (with mucus and blood) or constipation. The causative agents of acute intestinal infections can be bacteria, viruses, helminths and protozoa. This greatly complicates the diagnosis and often involves syndromic treatment.
Definition
Amebiasis (amebic dysentery) is an anthroponotic infection with a fecal-oral transmission mechanism. Its most basic manifestations are: chronic recurrent colitis and extraintestinal manifestations such as liver abscesses, ulcers and others. Most often, the term amoebiasis means amoebic dysentery, which is caused by the parasite Entamoeba histolytica.
Amoebic encephalitis and keratitis are distinguished among other amebiases. According to the World He alth Organization, about ten percent of the world's inhabitants are infected with this infection, and it is one of the main causes of death from parasitic diseases. Extraintestinal manifestations are very difficult to diagnose, thereforeit is not always possible to diagnose and treat amoebiasis in a timely manner.
Epidemiology
In all countries with a hot and humid climate, amoebic dysentery is common. Symptoms of this disease can most often be found in people who neglect sanitary and hygienic standards. Endemic for the pathogen are Central and South America, especially Mexico, and India.
Sometimes, large outbreaks of this intestinal infection are recorded in relatively prosperous countries, for example, in 1933 during the World Exhibition, which was held in Chicago. Currently, massive and sporadic cases of the disease appear in places of congestion of emigrants from endemic regions. Most often, the infection manifests itself in the warm season.
The source of infection is a sick person or a carrier of protozoa. Infection occurs only through dirty hands, food and water. Also, the disease can be transmitted through unprotected homosexual contacts. It is known that the cystic form of amoeba can spread on the legs and wings of insects.
Pathogen
Why does amoebic dysentery occur? Its causative agent belongs to the simplest, which can exist in three different forms:
- tissue (found only in sick people);
- translucent;
- cystic.
The last two are found in carriers of the disease. It is a cell up to 40 micrometers in size, which has a nucleus and many vacuoles. It uses pseudopods to move around in the human body. Bacteria, fungi, food particles are suitable for food. Amoebic dysentery is caused by this form.
Cyst is a round or oval cell measuring 30 micrometers. It can have several cores (from two to four), it depends on the stage of development.
Ameba life cycle
The cyst enters the human small intestine through dirty hands, water or greens. There, the cyst shell is destroyed, and a mature maternal amoeba enters the lumen of the organ. This form begins to divide. As a result of this process, eight new single-nuclear pathogens are formed. Dysentery amoebic begins at this moment. With a combination of favorable conditions of the body and a sufficient number of single-nuclear vegetative forms, amoeba continue to multiply and move further deep into the intestine.
In the course of their life, protozoa secrete substances that poison a person and cause the characteristic symptoms of an intestinal infection. With feces, vegetative and cystic forms enter the external environment. They can stay there for quite a long time. In addition, they are resistant to disinfectants.
Pathogenesis
How does such an ailment as amoebic dysentery develop? Infection begins with eating unwashed food. So amoeba get into the blind and ascending colon, where they may not manifest themselves for a long time. But in unfavorable for humansconditions (dehydration, poor nutrition, dysbacteriosis), cysts shed their shell, and a translucent form of amoebae appears.
With the help of its own cytolytic and proteolytic enzymes, the pathogen penetrates into the thickness of tissues, causing inflammation and the formation of ulcers and necrosis of small areas. In some cases, amoebas enter the blood vessels and with the flow of fluid enter other organs, forming abscesses there.
In the intestinal form of the disease, the inflammation spreads in a downward direction, from the caecum to the rectum. The mucosa of the organ is edematous, against the background of hyperemia, small nodules and ulcers are visible, which contain necrotic detritus and vegetative forms of amoebae. Over time, the nodules are destroyed, leaving in their place new ulcers up to two and a half centimeters in diameter. Deep defects on the bottom are covered with pus. If you examine the biopsy from the wall of the ulcer, you can find amoeba.
Chronization of the disease is accompanied by the formation of cysts, polyps and amoeba. These are tumor-like formations that consist of granulation tissue, eosinophils and fibroblasts.
Extraintestinal form
Amebic dysentery has both dyspeptic and somatic manifestations. When vegetative forms of amoebae penetrate the thickness of the intestinal wall, they can enter the systemic circulation. This leads to the spread of the pathogen throughout the body. Through the portal vein system, amoeba enter the liver parenchyma.
Lesions of varying severity can develop in the organ: from protein or fatty degeneration to severe hepatitis and liver abscess, which hasbelow the dome of the diaphragm. Sometimes it is also called a chocolate cyst because of the specific color of the pus. If the inflammation is not treated, then spontaneous opening of the abscess into the abdominal cavity occurs with the development of peritonitis. Or the cyst may rupture through the diaphragm into the lungs, mediastinum, or pericardium, causing complications. In addition to the liver, the pathogen can affect the brain, skin and other organs.
Clinic
The incubation period lasts about a week, after which amoebic dysentery appears. Symptoms begin with general weakness, pain in the iliac regions and a rise in body temperature. In ten percent of cases, the disease takes a fulminant course. It is characterized by profuse diarrhoea, with blood and mucus, which causes severe dehydration and death. Somewhere in a third of patients, fever is observed in combination with an enlarged liver. Inflammation at the onset of the disease is mild, so there are no characteristic changes in the general blood test.
Extraintestinal dysentery is accompanied by other manifestations. There is no symptom that could be called pathognomonic in this case. Amebiasis practically does not manifest itself in the body until a critical mass of the pathogen accumulates.
If no action is taken regarding the treatment of the disease, then after a while the infection becomes chronic. Gradually develops anemia and general exhaustion. The lower the body's resistance, the faster the intestinal form passes into the extra-intestinal one. The risk category includes young children, the elderly, pregnant women and patients taking immunosuppressants.
Diagnosis
By what criteria is the diagnosis of "dysentery" established? Diagnosis and treatment of this infection is closely related to the life cycle of protozoa. In order to find out the etiology of diarrhea, the doctor takes an analysis of feces, in which he finds tissue forms of amoebas. If there are cysts or luminal forms in the stool, then this indicates a carrier state and cannot serve as a confirmation of the diagnosis.
Since several types of amoebas already exist in the human body as opportunistic flora, diagnosis can be somewhat difficult. Misdiagnosis can also be made if Entamoeba dispar is found. This is a non-pathogenic amoeba, which is completely harmless to humans, but morphologically very similar to dysentery.
To verify the diagnosis, polymerase chain reaction and serological tests are also used. To detect extraintestinal forms of amebiasis, it is necessary to conduct an X-ray examination, ultrasound and computed tomography. Differentiate amoebic infection from shigellosis, salmonellosis and ulcerative colitis.
Treatment
Treatment of amoebic dysentery begins with cytostatics, such as metronidazole or tinidazole. If the patient is asymptomatic, either iodoquinode or paromomycin can be used to eliminate parasites.
The very first drug against amebiasis was emetine, which was mined in South America from ipecac. Now it is rarely used, since it is extremelytoxic and ineffective. This remedy is used only in case of a protracted course, with resistant forms and allergies to metronidazole.
For the treatment of extraintestinal forms, metronidazole is used in combination with yatren, doidoquine, mexaform and other drugs. In some cases, they resort to surgical intervention.
Complications
Amebic dysentery in humans can be complicated by perforation of the intestinal wall. This happens when a defect is too deep. With perforation, intestinal contents enter the abdominal cavity and infect it. The next complication is peritonitis. In order to save the patient's life, it is necessary to resort to surgical assistance: to make a median laparotomy and conduct a revision of the abdominal organs.
Another formidable complication is intestinal bleeding. It also develops during the formation of ulcers. For its relief, both conservative and surgical methods can be used. Healing ulcers can narrow the intestinal lumen due to the formation of scar tissue, thus disrupting the passage of food.
Prevention
Amebic dysentery is an intestinal infection, therefore, to prevent it, it is necessary to decontaminate the sources of the pathogen in a timely manner: dubious reservoirs, central water supply tanks and others.
In addition, it is necessary to carry out measures to identify carriers and spore excretors, as well as treat patients with acute forms in compliance with anti-epidemic measures. Convalescent people and carriers in neitherin no case should you be allowed to work in places of public catering.
Another way to reduce the number of infections is to promote personal hygiene and the proper handling of food before eating it. After an infection, a person should be regularly observed in the office of infectious diseases for a year. And only after the tests for three months will be negative for amoebiasis, the patient will be considered completely he althy.
