OVERVIEW
Schistosoma aegypti is caused by Schistosoma aegypti parasitizing the bladder veins and pelvic venous plexus and is characterized by clinical signs of terminal hematuria, bladder irritation with urinary tract obstruction.
Causes
1. Source of infection
Humans are the main source of infection, with no host for the parasite.
2.Transmission route
The eggs in human urine and feces contaminate the water source and spread after contacting the infected water.
3. Susceptible people
The infection rate is highest in the age group of 16～20 years old, and there is no difference between men and women.
Symptoms
1. Incubation period
The incubation period from the invasion of caecal larvae to the appearance of eggs in the urine is 10 to 12 weeks.
2. Acute stage
Symptoms are rare. Only a few have systemic symptoms such as fever and malaise. Urticaria is common. Liver and spleen may be enlarged. Eosinophilia in the blood.
3. Chronic stage
Early symptoms are painless terminal hematuria, which lasts for several months or years, and then symptoms such as urinary frequency and urgency gradually appear, followed by urinary difficulty. If complicated by urinary tract obstruction, hydronephrosis, secondary bacterial infection, and finally can cause renal failure. Cystoscopy reveals sand patches on the bladder wall produced by massive worm egg granulomas, proliferative inflammation of the mucosa, and stones composed of uric acid, oxalic acid and phosphate. The disease may predispose to carcinoma in patients aged around 40 years, mostly undifferentiated squamous cell carcinoma, and metastasis is rare and appears late. Hepatic and intestinal symptoms appear later. Liver and intestinal symptoms appear later and are less severe than in schistosomiasis. Lung symptoms are also less common. Male patients may have prostatitis and penile elephantiasis. Female patients may have labial papillae, which are easily misdiagnosed as carcinoma; in addition, ovaries and fallopian tubes may be involved.
Examination
1. Urine examination
The last few drops of blood urine can be centrifuged and precipitated, and the eggs can be found on direct smear. When the urine sediment is incubated, the larvae can be seen in 10 minutes to 2 hours.
2. Biopsy
Biopsy can be done directly from cystoscopy, and a large number of eggs can be detected by the compression method.
3. Imaging
Characteristic calcification, such as calcification of the bladder wall and calcification of the ureter, can be found in the urological X-ray film of patients who have been ill for a certain period of time. Urography can show hydronephrosis and narrowing of the bladder cavity.
4. Blood test
Eosinophilic granulocytes are significantly increased in the blood picture.
5. Immunologic examination
Serum immunologic examination has early diagnostic value in the acute stage.
Diagnosis
The diagnostic criterion for this disease is the finding of Schistosoma aegypti eggs in urine or stool. Patients with painless terminal hematuria in endemic areas should be considered for possible Schistosoma aegypti. Commonly used tests include: direct smear for eggs after centrifugal sedimentation of blood and urine; incubation of urinary sediment for trichinella; biopsy of bladder and rectal mucosa for eggs; and immunological tests.
Differential diagnosis
The clinical symptoms of schistosomiasis in Egypt are complex, and mainly need to be differentiated from urological diseases, such as kidney stones, nephritis, renal tuberculosis, bladder cancer, cystitis, and so on. When differentiating from the above urinary system diseases, on the one hand, it can be based on the patient’s history of disease, such as whether or not to enter the schistosomiasis endemic areas, etc. On the other hand, the clinical manifestations can also be distinguished from those of other diseases. On the other hand, through the clinical manifestations can also be distinguished from some diseases, such as schistosomiasis and most of the urinary system diseases have hematuria, urinary frequency, urinary urgency, urinary pain and other symptoms, but patients with renal calculi often appear colic or dull pain and urination can be discharged from the sandstone. Patients with renal tuberculosis have the symptoms of tuberculosis such as fever, loss of appetite, malaise, and night sweats in addition to the symptoms of the urinary system.
Complications
It often occurs in the late stage of Schistosomiasis Egyptianum, such as pyelonephritis, spermatozoal epididymitis, chronic renal failure, right heart failure, and bladder cancer.
Treatment
Pathogenic treatment mainly adopts
1. Praziquantel
It is a commonly used drug for the treatment of schistosomiasis, which is effective for Egyptian, Japanese and Mannheimer’s schistosomiasis.
2.Nilidazole
It is effective for Egyptian schistosomiasis. However, there are more side effects, mainly headache, dizziness, abdominal pain, anorexia, nausea, vomiting, diarrhea and so on. A few patients may have local or generalized convulsions and mental disorders, and hemolysis may occur in glucose 6-phosphate dehydrogenase deficiency.
3. Metronidazole
It is an organophosphorus agent with cholinesterase inhibiting effect, which can paralyze Schistosoma aegypti.
Prevention
There is no host for this disease, and human beings are the only source of infection. Therefore, the prevention and treatment of this disease need to strengthen the publicity and education of the residents of endemic areas, and do a good job of fecal, urinary, water pipes and personal protection.