What is Urinary Schistosomiasis?
Urinary schistosomiasis is a chronic helminthiasis with predominant damage to the urinary organs. Clinical manifestations are determined by the cycle of development of helminths in the human body, the localization of eggs in the tissues and the degree of damage to the urinary organs.
Causes of Urinary Schistosomiasis
The causative agent of urinogenital schistosomiasis is Schistosoma haematobium, which is widespread in large areas of Africa and the Middle East. In Egypt, schistosomes affect more than 50% of the population, in Iraq – 60-80%. The male is 4-15 mm long and 1 mm wide. The front of the body is cylindrical. On it are suckers. Posteriorly from the abdominal sucker, the body expands and on the ventral side, due to the convergence of the lateral surfaces, a gynecophore canal is formed. The female has dimensions up to 20 mm long and 0.25 mm wide. Most of her body is placed in the gynecophore canal of the male.
Oval-shaped eggs without a lid with a dark spike on one of the poles, their size 0.12-0.16 x 0.04-0.06 mm; excreted in urine. Intermediate hosts are the snails of the genus Bulinus.
The parasite is embedded in the skin of people bathing or working in water. Infection is possible with the use of infected water.
Through the blood vessels and lymphatic ducts of Schistosoma haematobium, it penetrates into the pelvic organs, where the female lays eggs into the lumen of the veins, which penetrate the vascular wall and enter the submucosa of the bladder and genitals. With contractions of their muscles, the eggs punch through the mucous membrane of the bladder and other urinary organs, where they are excreted with urine. Probably, Schistosoma haematobium eggs can be passed on to another person during sexual intercourse, especially among homosexuals.
In areas that are epidemic for schistosomiasis, eggs of schistosomes can be found in the male and female genitals. However, the role played by schistosomes in the occurrence of infertility or in spontaneous abortion is still unknown.
Helminths live 3–10 years, isolated cases have been reported where viable eggs were transmitted by a person infected 30 years ago.
In the inhabitants of endemic foci, the intensity of invasion increases during the first 10–15 years of life, and the incidence of urinary schistosomiasis in this age group increases. Further, the intensity of invasion decreases sharply, and the prevalence of the disease is moderate.
Pathogenesis during Urinary Schistosomiasis
Infection occurs during their contact with parasite-contaminated water when the parasite larvae, released by freshwater gastropod mollusks, penetrate the skin.
The basis of the pathogenesis of schistosomiasis are toxic-allergic reactions caused by secretions of the glands during the introduction of parasites and waste products and the breakdown of helminths. In the epidermis around the sites of introduction of cercaria edema develops with lysis of epidermal cells. In the course of the migration of larvae in the skin, there are infiltrates of leukocytes and lymphocytes.
Parasite eggs make their development cycle in the body of freshwater mollusks to the stage of cercariae, which are introduced through the skin into the human body. The cercariae very quickly mature and turn into schistosomils, which penetrate into the peripheral veins, where mature individuals are formed. From here, fertilized females are sent to their favorite habitat: pelvic veins, mesenteric and hemorrhoidal veins, as well as into the wall of the large intestine. Here the females lay their eggs, which causes tissue damage. Some eggs are excreted in the urine and feces into the external environment, being the source of the spread of helminthiasis.
Period infectious source. Infected people and animals secrete schistosomid eggs 40-60 days after infection or 1-2 weeks after the onset of clinical signs of the disease and then up to 1-2 years, although there are known cases of sexually mature worms in the human body up to 30 years. In infected mollusks, cercariae develop in water over a period of 4-5 weeks.
The natural susceptibility of people is high. The disease does not provide resistance to reinfection.
Pathological anatomy. With urinary schistosomiasis, 2-3 months after infection, hematuria and pain during urination often appear. These symptoms can occur throughout the life of adult worms.
First, a marked inflammatory reaction develops around the eggs of the parasite with the formation of granulomas, which leads to mechanical or functional obstruction of the urinary tract, hydro-tester and hydronephrosis, and appearance of filling defects in the bladder and ureters. With cystoscopy, you can see loose polypoid formations protruding into the lumen of the bladder, ulcers, punctate hemorrhages, granulomas. These early changes can be eliminated with the help of anthelmintic agents. Since helminth eggs enter the urine, they are easy to detect.
As the disease progresses, the inflammation subsides (possibly due to a weakened immune response) and the sclerotic changes are increasing (most likely due to the merger of a large number of old and re-emerging lesions). In the future, the lesion is represented mainly by schistosome bumps – clusters of dead and calcified parasite eggs in the connective tissue. With the accumulation of calcified eggs, the walls of the urinary tract more and more clearly appear on radiographs.
Hydrofoules and hydronephrosis due to fibrosis are irreversible and not treatable. Nevertheless, renal failure develops only in a small proportion of patients.
Urogenital schistosomiasis is not complicated by periportal fibrosis and glomerulonephritis, but eggs in the lungs can lead to pulmonary hypertension.
It is believed that urinary schistosomiasis contributes to the development of squamous cell carcinoma of the bladder, which significantly increases the incidence of complications and mortality.
The hematogenous spread of the process is possible: parasites are introduced into the liver, lungs, brain, and inflammatory infiltrates appear on the site of their introduction, granulation tissue (granulomas) is formed, and sclerosis develops.
Symptoms of Urinary Schistosomiasis
The average incubation period lasts 10-12 weeks (from the moment cercaria penetrates through the skin until the moment when the schistosome eggs are laid). Clinical manifestations develop already during periods of incubation, helminth migration, egg laying, tissue proliferation and recovery. At the time of penetration of the cercaria through the skin, a person feels pain as if punctured by a needle. During the migration of parasites, allergic phenomena such as pruritic dermatitis, eosinophilic infiltrates in the lungs and urticarial rashes develop. There are also symptoms of intoxication: anorexia, headache, pain in the limbs and night sweats. Blood leukocytosis and eosinophilia are noted. Sometimes the liver and spleen increase in size. The severity of clinical manifestations depends on the individual sensitivity of the patient and the massive invasion.
During the laying of eggs by schistosomes, distinct symptoms of intoxication are observed: an increase in body temperature, frequent urge to urinate. From the moment of laying eggs until they appear in the urine of patients can take several months. An early sign of this disease is the appearance of a drop of blood at the end of urination. In rare cases, blood is found in all urine.
The period of tissue proliferation and recovery begins from the moment of fixation of the eggs in the tissues. In this stage of the disease, schistosomotic hillocks appear around the eggs and microabscesses appear with subsequent fibrous changes in those tissues in which the helminth egg is retained. Often joins a secondary infection with the development of pyelonephritis. This period is characterized by symptoms of sluggish cystitis. Most patients indicate a cutting pain in the urethra during or at the end of urination, the appearance of drops of blood, weakness, fatigue, malaise, abdominal pain, often in the right hypochondrium, headache and muscle soreness. Patients noticeably lose weight. An increase in body temperature becomes persistent with significant fluctuations. Dysuric disorders reach a pronounced degree. Cachexia develops. Patients become disabled. The disease often leads to disability and premature death. Most often, it proceeds slowly, and patients remain functional for a long time. When cystoscopy determined by hyperemia of the mucous membrane of the bladder and swelling of the mouth of the ureter. In a later stage, the mucous membrane of the bladder is pale with the presence of schistosomiasis on it. During this period, the disease in men may experience epididymitis, proctitis, defeat of the seminal vesicles. Sometimes pseudo-elephantiasis of the genital organs, colitis and hepatitis develop.
Distinguish between mild, moderate, severe and very severe forms of the disease.
In the mild form of the disease in patients there are no complaints, dysuric disorders are minor, the efficiency remains.
In moderate form of the course, dysuric disorders are clearly expressed, the liver and spleen increase in size, and anemia develops.
Severe form is characterized by frequent exacerbations of chronic cystitis, lasting for years. Dysuric disorders are extremely debilitating. Urine dirty red, enlarged liver and spleen, anemia progresses. Patients lose their ability to work.
A very severe form is characterized by the development of complications: cirrhosis of the liver, pyonephrosis, pyelonephritis, bleeding from the dilated veins of the esophagus, cachexia, intercurrent infections. This form is difficult to treat and is often fatal.
Diagnosis of Urinary Schistosomiasis
Diagnosis of urogenital schistosomiasis is carried out on the basis of clinical data: weakness, malaise, urticaria, dysuric disorders, the appearance of drops of blood at the end of urination.
Schistosome eggs are excreted with the urine most intensely around noon. However, for their detection, the entire daily portion of urine is usually examined. If this is not possible, then urine collection takes place from 10 am to 2 pm. The collected urine is defended in high cans, the supernatant is drained, and the sediment is centrifuged. Sediment microscopy is carried out in a slightly darkened field of view, for which the microscope condenser is lowered. In view of the uneven release of eggs, repeat analyzes are performed.
To identify the blood fluke larvae, the urine is centrifuged as well as to detect eggs. Boiled non-chlorinated water is added to the precipitate and the sample is aged for 1 hour at 30 ° C. At the same time, the larvae hatch from the eggs – miracidia, the movements of which are clearly visible in the magnifying glass when the light passes.
Sometimes they resort to biopsy of a piece of pathologically changed mucous membrane of the bladder. A piece of biopsy tissue is crushed in a drop of glycerin between the slides and examined under a microscope.
In addition, cystoscopy and radiography of the urinary tract are used. With cystoscopy, it is possible to detect swelling of the mucous membrane of the bladder, hemorrhage, blurring of the vascular pattern, schistosomes tubercles (granular yellowish bodies the size of a pinhead). A pathognomonic sign of urogenital schistosomiasis is the presence of a “fly” – a speck on the mucous membrane of the bladder. These are dead calcified eggs of schistosomes. A convincing symptom is also the presence of a stricture of the intramural part of the ureter, star-shaped scars and papillomas on the mucous membrane of the bladder. The eggs of schistosomes that die in the bladder wall are calcified. This allows you to radiographically see the outline of the bladder in the form of an ellipse.
Immunological diagnosis is reduced to the use of intradermal allergy tests, complement fixation, precipitation and flocculation reactions.
Treatment for Urogenital Schistosomiasis
All infected urogenital schistosomiasis treatment is indicated. Dead and calcified parasite eggs are often found in tissues and urine, they should be distinguished from viable eggs.
Although a variety of drugs are used in urinary schistosomiasis, praziquantel is the drug of choice. Effective and metrifonat – safe drug for oral administration. Its main advantage is low cost, and the main disadvantage is that to cure the drug must be taken three times at intervals of 2 weeks.
The prognosis for timely medical and surgical treatment is generally favorable.
Prevention of Urinary Schistosomiasis
For the prevention of urinary schistosomiasis, all patients with helminthiasis should be treated to prevent the spread of infection.
Particular attention should be paid to measures to identify patients with schistosomiasis among foreigners arriving in the country from endemic areas of this invasion, as well as the implementation of preventive measures among Ukrainian citizens during their stay in these regions.
A significant role in the fight against schistosomiasis belongs to measures aimed at reducing the incidence and preventing transmission of infection.