Genitourinary schistosomiasis: causes, symptoms, diagnosis, treatment

Genitourinary schistosomiasis is a chronic tropical trematode, which proceeds with damage to the urogenital organs.

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Epidemiology of genitourinary schistosomiasis

Schistosomes live in small venous blood vessels of the genitourinary system, in venous plexus of the pelvis, bladder, uterus, found in the portal vein system and the branches of the mesenteric vein of mammals. They feed on blood, partially adsorbing nutrients through the cuticle.

The laid eggs migrate into the bladder, ripen for 5-12 days in the host tissues and are excreted from the body with urine. The final ripening of miracidia occurs in fresh water at a temperature of 10-30 ° C. In the water from the eggs come miracidia, which are introduced into the freshwater mollusks of the genus Bulinus, where within 3-6 weeks are developed to cercariae according to the scheme: miracidia - maternal sporocyst - daughter sporocysts - cercariae. Cercariae, coming out of the mollusk, are able to invade the final host within 3 days. Cercariae are introduced through the skin or mucous membrane of the oropharyngeal cavity into the body of the final host, where they are transformed into young schistosomes, migrate into the venous vessels of the genito-urinary organs, develop and reach sexual maturity. Mating occurs 4-5 weeks after penetration into the host, then the females lay eggs in small venous vessels.

With the help of an acute spike and cytolysins secreted by the larvae in the eggs, some eggs penetrate through the walls of the vessels and mucosal tissues into the lumen of the bladder, from where they are excreted in the urine. Many eggs linger in the wall of the bladder and surrounding tissues, causing inflammation. One pair of schistosomes produces 2000-3000 eggs a day. The life expectancy of adult schistosomes is on the average 5-10 years (although there have been cases of parasitizing them in humans for 15-29 years).

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What causes urogenital schistosomiasis?

Genitourinary schistosomiasis is caused by Schistosoma haematobium. The size of the male is 10-15 mm, the female is 20 mm (Fig. 4.1). The body of the males is thickened, flat, in females - filiform, longer. Suckers poorly developed. In the male, the cuticle behind the abdominal sucker forms a longitudinal slit-like gynecophore canal in which the female is placed with its lateral outgrowths.

The cuticle of the male is covered with spinules; in females, they are present only at the anterior end. There is no pharynx. Esophagus in males and females first bifurcates into two branches of the intestine, which then merge again. Testes - 4-5, they are located in the front or back of the body. The ovary is located at the confluence of the intestinal branches, behind it are the vitellaria. The genital pore is located behind the abdominal sucker. Eggs oval in shape, without lid, with characteristic terminal thorn, size 120-160 x 40-60 microns.

The causative agents are distributed in the countries of the tropical and subtropical belt between 38 ° N. W. And 33 ° S. In which, according to the WHO, up to 200 million new cases of infection occur annually. The incidence of schistosomes is highest in people aged 10 to 30 years. Increased risk of infection is subject to agricultural workers, workers of irrigation systems. The disease is widespread in most countries of Africa and the Middle East (Iraq, Syria, Saudi Arabia, Israel, Yemen, Iran, India), as well as in the islands of Cyprus, Mauritius, Madagascar and Australia.

According to its socio-economic significance among parasitic diseases, schistosomiasis is the second largest in the world after malaria.

Symptoms of urogenital schistosomiasis

The acute period of urogenital schistosomiasis coincides with the penetration of cercariae into the host and the migration of schistosomes through the blood vessels. In this period, at the stage of the introduction of cercariae, symptoms of urogenital schistosomiasis, such as vasodilation of the skin, redness, fever, itching and swelling of the skin are noted . These phenomena occur after 3-4 days. After the initial reaction and the period of relative well-being, which lasts for 3-12 weeks, the patient has headaches, weakness, aches in the back and limbs, multiple itching rashes like hives, and the number of eosinophils in the blood increases to 50% or more. Often the liver and spleen increase.

At the end of acute and early chronic periods, hematuria occurs, which is often terminal, i.e. Blood in the urine appears at the end of urination. Patients are concerned about general malaise, pain in the area of the bladder and perineum; the body temperature rises to 37 ° C and above, the liver and spleen increase even more. All these clinical symptoms of urogenital schistosomiasis are associated with the response of the human body to the implantation of eggs with schistosomes in the bladder tissue, genital organs and liver.

Passage of eggs through the wall of the bladder causes hyperemia of the mucosa and pinpoint hemorrhages. Around the dead eggs in the thickness of the wall of the bladder, granulomas are formed, and on their surface there are tubercles and polyposic growths. Due to mechanical damage to the mucosa passing through the wall of the bladder, eggs are often associated with a secondary infection and develop cystitis, which subsequently leads to severe destruction of the bladder tissue, ulceration of the mucous membrane. The inflammatory process can spread up the ureters to the kidneys.

The chronic period of the disease occurs a few months after the invasion and may last several years. The defeat of the ureters is accompanied by the narrowing of their distal sections and the mouth, which leads to stagnation of urine, the formation of stones and creates conditions for the development of pyelonephritis and hydronephrosis. The late stage of the disease is characterized by the development of fibrosis of the bladder tissue and its calcification, which makes it difficult to pass the eggs and promotes the intensification of granulomatous processes. Eggs in these cases are subjected to calcification. Their clusters form the so-called sand spots that are prominent in cystoscopy. As a result, the shape of the bladder changes, urine retention, intravesical pressure increases. The course of the disease can be mild, moderate and severe. In severe cases, the disease of genitourinary schistosomiasis leads to disability and premature death.

In men, the disease can be accompanied by fibrosis of the seminiferous tubules, orchitis, prostatitis, and in women - polyposis, ulceration of the vaginal mucosa and cervix. Perhaps the development of proctitis, the formation of fistulas of the bladder. Sometimes pseudoephanthiasis of genital organs, colitis and hepatitis develop. The defeat of the lungs leads to hypertension of the small circle of blood circulation. The development of fibrosis of organs, metaplasia of epithelium and immunosuppression promotes carcinogenesis. In the foci of schistosomiasis, tumors of the genitourinary system are more common than in other localities.

Diagnosis of urogenital schistosomiasis

In endemic foci, a preliminary diagnosis is made based on the clinical symptoms of urogenital schistosomiasis. Patients complain of weakness, malaise, urticaria, diuretic disorders, hematuria, the appearance of drops of blood at the end of urination.

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Laboratory diagnosis of urogenital schistosomiasis

The exact diagnosis of "genitourinary schistosomiasis" is established when eggs are detected with schistosomes in the urine, and they can be detected only 30-45 days after infection. Urine is taken during the hours of maximum egg excretion (between 10 and 14 hours). For ovoscopy, methods of concentration are used: sedimentation, centrifugation or filtration.

A very informative instrumental diagnosis of urogenital schistosomiasis. Cystoscopy reveals thinning of the vessels, blushing of the mucous membrane, deformation and hyperemia of the ureteral lobes, congestion of dead and calcified eggs with schistosomes, polyposis sprouting.

X-ray examination and serological methods (for example, ELISA) are also used additionally.

Treatment of urogenital schistosomiasis

Treatment of urogenital schistosomiasis in patients is carried out in a hospital. The drug of choice is prazikvantel or azinoks in a daily dose of 40 mg / kg in two divided doses during the day. The effectiveness of the drug is 80-95%. Important in the treatment of schistosomiasis is given to the methods of symptomatic and pathogenetic therapy for the improvement of the functions of the affected organs and systems. With secondary infection, antibiotics are used. In severe cirrhosis, splenic vein thrombosis, polyposis, strictures, surgical treatment is performed.

Prophylaxis of urogenital schistosomiasis

Genitourinary schistosomiasis can be prevented if one observes a set of measures aimed at stopping the transmission of infestation and preventing the infection of people:

• timely detection and treatment of patients;
• prevention of the ingress of eggs with schistosomes into water bodies inhabited by mollusks;
• the destruction of mollusks with the help of molluscicides (mural, sodium pentachlorophenolate, copper sulfate, endode, etc.);
• settling in the reservoirs of competitors of mollusks and predators, which destroy the eggs of mollusks and themselves;
• use of irrigation systems that reduce the reproduction of mollusks;
• cleaning and drying channels and reservoirs;
• wearing protective clothing (gloves, rubber boots, etc.) in contact with water;
• lubrication of the skin with protective ointment (40% dimethyl phthalate or dibutyl phthalate) during bathing and working in water;
• boiling or filtration of water for drinking and household needs;
• active health education work;
• centralized water supply of the population.

Special measures are taken by personal prevention measures for tourists and travelers in endemic areas. These measures include careful selection of places for bathing, avoidance of freshwater reservoirs overgrown with vegetation and places of conglomeration.