Isospora Belli: Coccidia, Life Cycle, Treatment

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Isospora Belli: Coccidia, Life Cycle, Treatment
Isospora Belli: Coccidia, Life Cycle, Treatment

Video: Isospora Belli: Coccidia, Life Cycle, Treatment

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Video: Cystoisosporiasis/ Isospriasis 2023, February

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  • Localization locations
  • Infection mechanisms
  • Pathogenesis (what happens?) During isosporosis
  • Symptoms
  • Complications
  • Isospora belli diagnostics
  • Treatment
  • Forecast and prevention
  • You can defeat parasites!

Isospores are widespread in nature, there are more than 200 species of them, but only 2 of them cause pathology in humans. Isosporosis is anthroponosis, since Isospora belli and I. natalensis affect only humans.

Isospora belli
Isospora belli

What to do in such a situation? To get started, we recommend reading this article. This article details the methods of dealing with parasites. We also recommend contacting a specialist. Read the article >>>

Localization locations

In addition to the intestine (small intestine, duodenum), isospores parasitize other organs of the human body. The medium for the reproduction of oocysts can be tissues of the heart, kidneys, liver, eyeballs.

The body's response to the vital activity of parasites depends on where the protozoa live:

  • in the presence of oocysts in the small intestine, flatulence is observed in humans;
  • the patient suffers from anemia if the parasites feed on blood;
  • deviations in the work of the central nervous system due to its intoxication.

With the defeat of the simplest parasites of the respiratory system in the lungs, gas exchange processes are disrupted. When infected with isospores, a person suffers from shortness of breath and cough, accompanied by the separation of sputum.

Infection mechanisms

Foci of infection arise in public places where a large number of people are in contact. Children attending child care facilities are especially susceptible to infection:

  • school;
  • Kindergarten;
  • sports sections, circles.

Contaminated food (not washed fruits, vegetables), dirty water are the usual ways for sporozoans to enter the human body, dirty hands are fecal-oral penetration.

Infection mechanisms
Infection mechanisms

Reference! High incidence of isosporosis in tropical countries

Isospores will begin to multiply as soon as they enter the intestines. The incubation period is 5-10 days.

List of foods that may contain parasites:

  • milk;
  • cheese;
  • sausage;
  • kebab.

Oocysts, once outside the human body, do not die, they adapt to new conditions. They begin to multiply and develop, getting along with the dirt into the human food tract. In the process of development, they are transformed into various forms: oocysts, sporozoites, schizonts, merozoites, macrocomets.

Pathogenesis (what happens?) During isosporosis

The source of infection is humans. Infection occurs when drinking water or food contaminated with oocysts. Diseases are more often observed in children, both sporadic and small epidemic outbreaks (in children's institutions). In tropical countries, the incidence is much higher.

In the external environment, isospores undergo asexual development cycle, forming oocysts.

A person becomes infected by the alimentary route: oocysts enter his intestines with contaminated water and food. The cycle of isospore development in the intestine can be asexual (in these cases, parasites, invading the epithelial cells of the mucous membrane of the duodenum and jejunum, go through a repetitive reproduction cycle by division, as a result of which more and more new cells are involved in the process). From individual merozoites (one of the stages of development of the parasite) germ cells are formed, which, merging, form immature oocysts.

Reproduction of Isospora belli in the epithelial cells of the intestine leads to its damage, disruption of the processes of absorption of fluid and nutrients from the intestinal lumen - diarrheal syndrome develops, accompanied by cramping pain in the abdomen. Stools are frequent, watery, the temperature is often subfebrile.

The process in an immunocompetent organism usually proceeds favorably, all phenomena subside within 7-10 days, even without treatment. Many infected people do not develop diarrheal syndrome at all, although isospores are found in feces.

Pathogenesis (what happens?) During isosporosis
Pathogenesis (what happens?) During isosporosis


The clinic of isosporosis is characterized by symptoms of enteritis. The incubation period lasts 5-7 (up to 10) days. The disease begins with an increase in body temperature (sometimes up to 39 ° C). The febrile period can last up to a week. Simultaneously with an increase in body temperature or on the 2-3rd day after that, profuse watery diarrhea develops, sometimes with an admixture of a small amount of mucus and blood. In some patients, vomiting is observed. In some cases, oocysts can be found in the feces of people who do not have obvious clinical manifestations.

Typically, the disease is acute, ending with recovery 7-20 days after its onset. Occasionally, severe cholera-like forms of isosporosis and cases of its protracted course are observed. They are observed in people with reduced immunity or in patients with AIDS. In these cases, parasites can go beyond the mucous membrane of the small intestine and cause the development of disseminated isosporosis, which often leads to the death of the patient.


Due to the difficulties in diagnosing Isospora belli in immunocompetent individuals, this pathology is rarely recorded and goes away on its own without special treatment. Complications and deaths have not been described. There are only mentions of isolated cases of cholera-like course. Isosporosis is considered an opportunistic infection; in case of immunodeficiency, it acquires a protracted chronic character with diarrhea lasting up to several months or proceeds in a severe form with grade 3 exicosis.

Against the background of a pronounced lack of nutrients, patients lose up to 25% of their body weight. Severe electrolyte disturbances and metabolic acidosis are formed. Severe dehydration can cause hypovolemic shock. When the parasite enters the bloodstream, a disseminated process develops with a possible fatal outcome.

Isospora belli
Isospora belli

Isospora belli diagnostics

When symptoms of gastroenterocolitis appear, patients are hospitalized in an infectious diseases hospital. During the examination, the infectious disease doctor draws attention to the severity of the symptoms of dehydration. Severe exicosis is characterized by lethargy, decreased elasticity of the skin, dryness of the mucous membranes, the appearance of a "white spot" symptom. Deafness of heart sounds, decreased urine output are noted.

The following laboratory methods are used for diagnosis:

  • General research. A feature of isosporosis is increasing eosinophilia in the general blood count, which can reach 60%. The concentration of hematocrit and hemoglobin increases. In the biochemical analysis of blood, with severe dehydration, electrolyte shifts are possible. In the coprogram, mucus, steatorrhea, leukocytes, bacteria are determined, however, such changes are not strictly specific for this pathology.
  • Identification of the pathogen. Stool smear microscopy is done to make a diagnosis. Oocysts from the human body begin to be secreted about 10 days after the onset of the disease, when the stage of sexual reproduction begins and clinical manifestations subside, which must be taken into account when prescribing a study. After the onset of clinical recovery, oocysts can be detected in human feces for up to 1-2 months, on average up to 20 days. Additionally, the ELISA method is used.

Differential diagnosis is carried out with diseases provoked by various bacterial pathogens that can cause similar stool disorders: salmonella, Klebsiella, clostridia, as well as viral infections - rotavirus and adenovirus. Taking into account abdominal pain, diarrhea, fever, it is necessary to distinguish isosporosis from surgical diseases with the clinic of "acute abdomen", for example, appendicitis and pancreatitis.


To normalize the stool, pathogenetic and symptomatic therapy is carried out. Oral rehydration with glucose-saline solutions, infusion therapy with polyionic crystalloids, enterosorbents are prescribed. The listed measures are aimed at restoring the pathological and physiological losses of the body. When the body temperature rises, antipyretics are used, for example, paracetamol, a mixture of analgin with diphenhydramine.

In persons with immunodeficiency, isosporosis becomes severe. In the initial stages, a broad spectrum antibiotic such as ciprofloxacin can be used 15-20 times a day with stool. After determining the pathogen, trimethoprim, metronidazole, pyrimethamine are prescribed. Additionally, biological products containing live lyophilized bacteria are used. Lacto- and bifidobacteria are more suitable for the intestinal microflora.


Forecast and prevention

In the absence of immune disorders, the outcome is favorable. Symptoms disappear without a trace after 10-20 days, oocysts can be excreted with feces from the host's body for up to 2 months. With immunodeficiency, the prognosis is serious. The infection becomes chronic and may result in the death of the patient.

Dispensary observation is carried out only in HIV-infected patients. Non-specific preventive measures include adherence to personal hygiene rules and the prevention of environmental pollution. To prevent relapses, AIDS patients take co-trimoxazole and pyrimethamine for up to 3-4 weeks.

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