The prevalent schistosome in China is Schistosoma japonicum, also known as Schistosoma japonicum. Adult schistosomes parasitize the portal vein, the inferior mesenteric vein, and the suprahemorrhoidal venous plexus of end-hosts such as humans. Humans are one of the terminal hosts of Schistosoma, and the snail is its only intermediate host. Schistosoma haematobium eggs discharged from the carrier or the patient's body, with the feces into the water, in the appropriate environment within the eggs of the trichinella can break eggs and out in the water can survive for 1 to 3 days, encountered the intermediate host of the snail, that is, the use of their own secretions of the cephalic glands, invade the body of the snail, the development of the snail in the body and asexual reproduction, the first to form the mother of the microfilariae, and its reproductive embryonic mass developed into many subcellular microfilariae, subcellular microfilariae detached from the parent body, batches of Form a large number of tailed larvae, tailed larvae break through the body wall of the sub-cellular larvae, the use of head gland secretion to dissolve the snail body tissue, into the water in batches. After entering the water, the tailed larvae often hang upside down or swim under the surface of the water near the shore, if the host skin or mucous membranes in contact with the epidemic water, after a few minutes, the tailed larvae can utilize the dissolving effect of the secretion of the drilling gland to drill into the skin of the human body and molt off the skin to become a child worm. After drilling into small blood vessels or small lymphatic vessels in the skin or mucous membranes of the host, the larvae enter the right heart and lungs along with the blood flow or lymphatic fluid, and then pass through the alveolar capillaries to the left heart to enter the body circulation. Most of the child worms develop in the hepatic portal vein system branching off in the bloodstream and then migrate against the bloodstream to settle in the parasitic site and develop into adult worms.

Schistosoma haematobium is usually infected through the skin, but it can also be infected through the mouth.

Schistosomiasis is an immunologic disease. Humans have no innate immunity to schistosomes, but are immune to some, but not all, avian schistosomes. Schistosoma japonicum can cause the following diseases:

1, caecal dermatitis: caecal larvae burrowed into the skin a few hours to 2~3 days after the invasion of the invasive parts of the capillary dilatation, congestion, accompanied by hemorrhage, edema, the severe cases can cause generalized edema and erythema, local itching, the emergence of small red papules. This disease occurs only in patients who have ever been infected with schistosomes.

2. Damage caused by the migration of child worms in the body: it can cause capillary rupture, hemorrhage, local cellular infections and pitting hemorrhage, most obvious in the lungs, coughing, blood in the sputum, and general malaise, etc. Symptoms such as lung symptoms and X-ray changes can occur in early infection.

3. Slight damage to blood vessels in the host site caused by adult worms, such as phlebitis and perivenous inflammation.

4, worm egg granuloma: the most important lesion caused by schistosomes.

Clinical manifestations:

According to the clinical manifestations and pathological changes can be divided into acute, chronic, late, ectopic schistosomiasis.

Acute schistosomiasis: symptoms appear 5-8 weeks after infection, the main symptoms are: high fever with chills, loss of appetite, nausea, vomiting, abdominal pain, diarrhea, mucous blood stools or pus and blood stools, liver and spleen enlargement, dry cough, blood in sputum, shortness of breath, chest pain, chest infiltrating shadows on X-ray, leukocytes and eosinophils increase, can be accompanied by urticaria, enlarged lymph nodes, joint pain. In severe cases, anemia, depression, jaundice, ascites, etc., and death in severe cases.

Chronic schistosomiasis: there may be no symptoms or symptoms. Symptoms often have abdominal pain, diarrhea, mucous blood stools, mild hepatosplenomegaly.

Advanced schistosomiasis: can be categorized as megasplenic: the patient feels an enlarged mass in the left upper abdomen, accompanied by a feeling of heaviness. Splenomegaly over the umbilical plane. Hypersplenism. Ascites type: portal hypertension and ascites are present, which may be complicated by hepatic coma, upper gastrointestinal bleeding (rapid and heavy bleeding), and even cancer. Dwarf type: it is caused by childhood infections, and is omitted. Colonic thickening type: the intestinal wall forms a mass toward the abdominal cavity, or forms a polyp toward the intestinal lumen, often with abdominal pain, diarrhea and other symptoms.

Ectopic schistosomiasis: caused by adult schistosomes parasitizing veins outside the portal system. Parasitism and damage are common in the lungs and brain. In the pulmonary form, patients have a dry cough, mucus sputum, and flocculation and spotting on X-ray. The cerebral form presents with headache, impaired consciousness, coma, and hemiparesis.

Treatment:

Therapeutic drugs are preferred to praziquantel, which has high efficacy, short duration and low toxicity. Followed by Oxyquin, Metronidazole and so on. For advanced patients first use traditional Chinese medicine to regulate, and then kill the worms or surgical treatment.