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Isosporosis: Causes, Symptoms, Diagnosis, Treatment
Last reviewed: 23.04.2024
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Isosporosis is an anthroponic disease that affects only a person and is characterized by acute enteritis or enterocolitis and spontaneous recovery. In immunosuppressive individuals, the disease becomes chronic (chronic diarrhea) and can be fatal.
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Epidemiology of isospore
Isosporosis is anthroponous disease, the only host whose causative agent is a human. The source of infestation is only a person with acute or chronic forms of isospore, or a carrier. Oocysts in the feces of the patient appear only on the 10-12th day from the onset of the disease. Immediate transmission of the pathogen from person to person does not occur, t. Oocysts ripen under aerobic soil conditions for 2-3 days. Thus, the minimum turnover time of infection is 2 weeks (2-3 days in the environment and 10-12 days in the human body). The most active release of pathogens occurs after 16-30 days from the onset of the disease, therefore, patients with isosporia are the most dangerous during the period of stagnation of clinical symptoms.
The mechanism of infection is fecal-oral.
Foci of isospore are confined to tropical and subtropical regions. Sporadic cases are found everywhere.
What causes isosporia?
Isosporosis is caused by representatives of the simplest genus Isospora. In humans, I. Belli and I. Natalensis are caused. The life cycle of isospores consists of two phases - exogenous (development in the external environment) and endogenous (development in the human body). Characteristic is the alternation of asexual (in the external environment and in the human body) and sexual (only in the human body) reproduction. After the maturation of the oocyst, which has entered the human intestine, sporozoites emerge from it, which enter the epithelial cells of the 12-finger and jejunum, where they are located under the nucleus of enterocytes. Sporozoites are transformed into trophozoites, which grow and increase in size, then, after maturation, the nucleus is divided many times, and as a result, a shison is formed. A cytoplasm is separated around each daughter nucleus. Merozoites formed from a schizont fall out of the affected epithelial cells into the lumen of the intestine and affect more and more new enterocytes. Later, some of the merozoites are transformed into males (microgametocytes) and female (macrogamethocytes). From macrogametocytes mature macrogametes are formed that occupy the entire enterocyte. Multiple fission of the nucleus occurs in the microgametocyte. The newly formed nuclei have an elongated shape, they separate from each other by a small amount of cytoplasm and turn into small microgametes having 2 flagella, and leave the enterocyte. Then microgamets actively penetrate into the macrogamet, which turns into a zygote, and then into the immature oocyst. Immature oocysts are released into the environment with feces, where at a temperature of +25 ° C they transform into sporocysts within 2-3 days, in each of which 4 sporozoites are formed in 18-36 hours. Mature isospore oocysts are very stable in the environment: low temperatures of 0-5 ° C slow down sporulation, but under favorable conditions it resumes, at a temperature of -21 ° C sporulated isospores survive until the first month.
Pathogenesis of isosporosis
Endogenous forms of isospores destroy the epithelium of the villi of the lean and ileum, where the metronium is completed. With extensive lesions, leukocyte exudate is formed, the structure of the cylindrical epithelium changes, villous atrophy, metaplasia of enterocytes, crypt hyperplasia occur. All this leads to impaired absorption and the development of malabsorption syndrome.
Symptoms of isosporia
The incubation period of isospore is an average of 7 days. In immunocompetent persons, isospore disease occurs as acute enteritis or enterocolitis, accompanied by a loose stool with an admixture of mucus, sometimes blood; Simultaneously there are common symptoms of isospore: nausea, vomiting, anorexia). Disturb pain throughout the abdomen, both permanent and cramping. Isospore disease is self-healing within 18-31 days.
Immunosuppressive individuals, including HIV-infected people, develop a chronic form of the disease, accompanied by steatorrhea, loss of proteins, which leads to a rapid decrease in body weight to 25% or more. Disturbances of absorption of D-xylose and vitamin B 12 are violated. The outcome may be lethal. In patients with AIDS, isosporia occurs quite often and is one of the causes of death of these patients
Diagnosis of isosporosis
A characteristic sign of isosporia is an increasing eosinophilia. Isospores can be found in human feces by using the method of enrichment followed by microscopy of smears, tk. Parasites in stool a little. The study is carried out repeatedly, the most informative it is considered in the period from the 16th to the 31st day of the onset of symptoms.
What do need to examine?
How to examine?
Isosporosis treatment
Treatment isospore is mostly symptomatic (see Cryptosporidiosis ). Etiotropic treatment of isosporia has not been developed.