Schistosomiasis: Types, Symptoms, Diagnosis And Treatment

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Schistosomiasis: Types, Symptoms, Diagnosis And Treatment
Schistosomiasis: Types, Symptoms, Diagnosis And Treatment
Video: Schistosomiasis: Types, Symptoms, Diagnosis And Treatment
Video: Schistosomiasis | Bilharziasis | Causes, Symptoms and Treatment 2023, February

Schistosomiasis is a parasitic disease caused by blood flukes, schistosomes from the genus of trematodes of the Strigeidida order, which occurs with allergic reactions, damage to the digestive and genitourinary systems.


Schistosomiasis is one of the most common and dangerous trematodes in humans. The World Health Organization (WHO) notes that at present, every 25th person on the planet is infected with schistosomiasis, and up to 200,000 people die from it every year. The disease ranks second in the world among serious fatal diseases, after malaria. In addition, this parasitic disease with the development of tourism is increasingly expanding the boundaries of its spread. People living in northern countries return from travel infected with these exotic parasites. Given this fact, you should pay special attention to this disease and consider all the nuances of its occurrence, diagnosis and treatment.


  1. Schistosomiasis disease - description
  2. Penetration routes
  3. Classification
  4. Intestinal schistosomiasis
  5. Genitourinary schistosomiasis
  6. Treatment of schistosomiasis
  7. Prevention

Schistosomiasis disease - description

The causative agents of schistosomiasis are flat, heterosexual blood flukes, which are small in size 20 mm in length and 0.25 mm in width. On the body of the fluke, there is a suction organ with two suction cups: oral and abdominal, with the help of which the helminth is fixed to the host's skin. And with the help of specially secreted enzymes and active movement, schistosome larvae penetrate the capillaries of the skin. After penetration, the larvae (cercariae) reach the portal vein and its hepatic branches, and after a few weeks they finally settle in the duodenal, venous plexuses and vessels of the urinary bladder. After three months, the larvae turn into sexually mature individuals and begin to lay eggs. The eggs laid by the female are transported with blood flow to the bladder, intestines and other organs.There, their further development and mating and laying of eggs take place. Eggs of schistosomes have a characteristic feature, which lies in their ability to pass through the vascular wall, exit into the surrounding tissues and the lumen of hollow organs (intestines and bladder) and from there be released into the external environment.


Schistosomes of any kind pass through human skin and enter the venous system. For this reason, they are percutaneous biohelminths. The final owner of this helminth is a person, as well as some animals that, with urine and feces, release schistosom eggs into the environment. For the further development of eggs, a freshwater reservoir is needed, since their next development cycle takes place in water. In such reservoirs, miracidia are released from the eggs of schistosomes. For the next stage of development, miracidia need an intermediate host, which becomes a freshwater mollusk. In the body of the mollusk, further development of the schistosome takes place, which turns into invasive larvae - cercariae. Mature cercariae leave the body of the mollusk, go out into the water and go in search of a new host.People or animals bathing in a pond become the final hosts of schistosomes, which penetrate the body by percutaneous route (through the skin). In the human body, cercariae make a complex and lengthy migration, penetrating the vessels of the abdominal cavity, where they become sexually mature individuals and fertilized females lay eggs. They usually parasitize in the small veins of the colon, small pelvis, uterus, abdominal cavity. The disease can last from 5 to 15 (or more) years.The disease can last from 5 to 15 (or more) years.The disease can last from 5 to 15 (or more) years.

It so happens that a person can simultaneously become infected with three types of schistosomes at once, which enter the body from freshwater reservoirs. Adults feed on blood and mate in venous blood. Depending on the localization of helminths in the body, symptoms are observed that are characteristic of the defeat of a particular organ or system.

In the migratory stage, the larvae of schistosomes carry out destructive activity, which consists in the destruction of small blood vessels, which provokes a variety of hemorrhagic reactions.

Penetration routes


Schistosomes enter the body in the following ways:

  • through the skin while swimming in a freshwater reservoir;
  • while washing clothes in a freshwater reservoir;
  • while fishing;
  • during outdoor recreation;
  • if the rules of personal hygiene are not followed;
  • when working in the garden;
  • in connection with work (work in the agricultural industry).

Young children are very vulnerable to this type of parasitosis, since they are not able to independently observe the rules of personal hygiene.

There is another, recently widespread, type of infection with this helminthiasis - ecotourism and migration of people to other countries. When traveling to hot tropical countries, people become infected with schistosomiasis. Therefore, after returning from a country with a tropical climate, it is necessary to undergo an examination to identify parasites.


There are several types of schistosomes that are localized in different organs and cause various diseases.

Schistosoma mansoni - the causative agent of intestinal schistosomiasis; In the human body, five types of helminths of the Schistosomatidae family can parasitize:

  • Schistosoma haematobium - the causative agent of genitourinary schistosomiasis;
  • Schistosoma intercalatum - causative agent of intercalate schistosomiasis;
  • Schistosoma japonicum - the causative agent of Japanese schistosomiasis;
  • Schistosoma mekongii is the causative agent of mekong schistosomiasis.

The most common in countries with temperate climates are:

  • intestinal schistosomiasis;
  • genitourinary schistosomiasis.

Intestinal schistosomiasis

Manson's intestinal schistosomiasis (schistosomosis enterica Mansoni) is a parasitosis that mainly affects the intestines, several types of trematodes provoke the disease at once. Helminthiasis has a long current course with periodic exacerbations, which are complicated by anemia and cirrhosis of the liver.

The disease proceeds with allergic reactions caused by the metabolic products of parasites that allergize the body. In the places of introduction of the larvae, edema with the process of lysis (dissolution of cells) of the skin is observed. During the migration of larvae, infiltrates of leukocytes and lymphocytes are formed in the skin.

There are two stages of intestinal schistosomiasis:

  • sharp;
  • chronic.

Intestinal schistosomiasis in the acute stage is a consequence of allergic sensitization of the body. Symptoms appear 4-16 weeks after infection.

During this period, the patient feels symptoms from the digestive system:

  • loose stools with blood and mucus;
  • stomach ache;
  • nausea and vomiting;
  • enlargement of the liver and spleen;

From the pulmonary system, there is:

  • coughing up phlegm;
  • shortness of breath and cyanosis;
  • tachycardia;
  • hypotension.

An increase in eosinophils and leukocytes is noted in the blood. An itchy rash, redness and swelling appear on the skin.

Along with intestinal manifestations, symptoms from the nervous system are observed:

  • apathy;
  • irritability and agitation;
  • adynamia;
  • coma (rare).

The chronic stage of the disease is characterized by inflammatory reactions in the tissues, granulomatosis and fibrosis.


The main symptoms during this period develop from the gastrointestinal tract: pathological changes in the wall of the colon, liver and lungs.

There are three main types of chronic intestinal schistosomiasis:

  • interstitial;
  • hepatosplenomegalic;
  • pulmonary.

The interstitial form develops as a result of damage to the large intestine. In this case, the following symptoms develop:

  • persistent diarrhea alternating with constipation;
  • aching abdominal pain;
  • cracks in the anus;
  • hemorrhoids.

In hepatosplenomegalic form of intestinal schistosomiasis, there is a dysfunction of the liver and spleen with the following symptoms;

  • enlargement of the liver and spleen;
  • pain and a feeling of heaviness in the right hypochondrium;
  • loss of appetite;
  • losing weight;
  • development of edema in the legs;
  • abdominal ascites;
  • gastric and esophageal bleeding;
  • cirrhosis (with a long course of the disease).

With a long course of the disease, the patient dies from liver failure, thrombosis of the liver vessels, bleeding, or from acute heart failure.

The pulmonary form of intestinal schistosomiasis is manifested by the following diseases:

  • asthenia;
  • increased fatigue;
  • weakness;
  • dyspnea;
  • tachycardia;
  • headaches and dizziness;
  • pain in the chest area.

The proliferation of granulomas and fibrous tissue around the eggs of schistosomes, which enter the liver through the portal system, leads to the development of portal hypertension. Varicose veins of the stomach and esophagus develop, and the spleen increases in size. With stagnation in the portal vein system, parasite eggs are carried into the pulmonary and other systems. Also, the penetration of eggs into the gallbladder, pancreas, appendix, genitals, back and brain can cause damage to these organs. As a result, the following complications may develop:

  • stomach bleeding;
  • phlegmon and stomach abscesses;
  • bleeding from the veins of the esophagus;
  • development of pulmonary heart syndrome;
  • adhesive disease;
  • rectal polyposis.

Treatment of intestinal schistosomiasis

To treat this type of schistosomiasis, use:

  • praziquantel or azinox at a dose of 40 mg per 1 kg of body weight in two divided doses during the day;
  • oxamniquine at a dose of 15 mg per 1 kg of body weight in one dose;
  • niridazole at a dose of 25 mg per 1 kg of body weight in one dose, the course of treatment is 5–7 days.

Also, symptomatic and pathogenetic treatment is carried out to improve the functions of the affected organs. Antibiotics are prescribed for re-infection.

Genitourinary schistosomiasis


Acute genitourinary schistosomiasis develops as a result of the penetration of larvae (cercariae) into the genitourinary system. There are two stages:

  • sharp;
  • chronic.

At the stage of introduction of larvae into the skin, the following symptoms are observed:

  • itching and swelling of the skin;
  • vasodilation of the skin;
  • redness of the sites of introduction;
  • local skin fever.

After the initial reaction of the body, an acute form of genitourinary schistosomiasis begins, which is manifested by the following symptoms:

  • headaches and dizziness;
  • aching joints;
  • weakness and asthenia;
  • itchy rashes (hives);
  • the growth of eosinophils in the blood count;
  • enlargement of the liver and spleen;
  • hematuria (blood in the urine at the end of urination).

Further, there are clinical symptoms that are associated with the body's response to the penetration and localization of schistosome eggs in the tissues of the bladder, genitals and liver.

During this period, patients also complain of general weakness and malaise, pain in the bladder, subfebrile temperature (37.5 ° C), and on palpation, an even greater increase in the liver and spleen is noted.

The penetration of the eggs of the parasite through the wall of the bladder causes hyperemia of the mucous membrane and minor hemorrhages. Granulomas form inside the bladder wall, around the dead eggs, and on the surface of the walls - bumps and polyps. Due to mechanical damage to the mucous membrane, which is caused by the passage of the egg through the wall of the bladder, a secondary infection develops in the form of cystitis. In the future, it leads to severe destruction of the tissues of the bladder and ulceration of the mucous membrane. Inflammatory processes can affect the ureters and kidneys, as they can spread upward.

The chronic stage of genitourinary schistosomiasis occurs several months after the development of the acute stage and can last for several years, and sometimes for a lifetime. This period is characterized by further damage to the genitourinary system, which leads to:

  • narrowing of the distal ureters;
  • stagnation of urine;
  • the formation of stones;
  • pyelonephritis and hydronephrosis;
  • fibrosis of the bladder;
  • calcification of the bladder.

The accumulation of eggs of schistosomes form the so-called sandy spots, which are clearly visible during cystoscopy. Their accumulation leads to a change in the shape of the bladder, urinary retention, and increased intravesical pressure.

Genitourinary schistosomiasis can occur in mild, moderate and severe forms. In extremely severe cases, genitourinary schistosomiasis leads to disability and early death.


Treatment of genitourinary schistosomiasis

Genitourinary schistosomiasis involves inpatient treatment. Therapy is carried out in two directions:

  • etiotropic therapy;
  • symptomatic therapy.

Etiotropic therapy involves treatment with antihelminthic drugs. The best drugs are praziquantel or azinox at a dose of 40 mg per kg of body weight twice during the day.

Symptomatic and pathogenetic therapy is of great importance in restoring the functions of the affected organs and systems. When a secondary infection is attached, antibiotics are used. In severe cases, with complications in the form of splenic vein thrombosis, cirrhosis, and polyposis, surgical treatment is indicated.

Treatment of schistosomiasis

Diagnosis of schistosomiasis includes the following studies:

  1. Analysis of urine. In the acute stage, the largest number of eggs excreted in the urine is excreted from 10 to 14 days.
  2. Stool analysis. To detect schistosome eggs in feces, a coprogram is made and various coproovoscopy methods are performed. Among them: the study of smear, sedimentation after dilution of feces, the study of smears according to Kato-Katz.
  3. Cystoscopy. This study reveals specific changes in the mucous membrane of the urinary bladder: "sand spots", infiltrates, granulomas, black microgranulations.
  4. Endobiopsy. This method involves taking a sample of tissue, in the thickness of which schistosomes can settle.
  5. Contrast urography. With the help of this study, changes in the structure of the ureters are detected.
  6. Radiography. Allows you to detect changes in the kidneys and infiltrates in the lungs.
  7. Fibrocolonoscopy. This study, together with endobiopsy, can reveal organ and functional disorders in tissues.
  8. Pelvic and abdominal ultrasound can help identify schistosomal infiltrates.

Also very informative are immunological tests - RSK, RNGA, ELISA. In endemic areas, intradermal allergy tests with schistosomal antigen are used to identify infected individuals. Genitourinary schistosomiasis is differentiated from bladder tuberculosis and urolithiasis, intestinal schistosomiasis - typhoid fever, colon cancer, amebiasis, dysentery.


Prevention of schistosomiasis consists of:

  • in the timely identification and isolation of infected persons;
  • the destruction of gastropods, which act as intermediate hosts in the life cycle of schistosomes;
  • disinfection of freshwater reservoirs;
  • boiling or filtering drinking water;
  • compliance with the rules of personal hygiene;
  • control of persons at risk;
  • improving the quality of sanitary control;
  • health education of the population.

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