Mekong schistosomiasis
Introduction
Introduction to schistosomiasis The schistosomiasis was first discovered in southern Thailand in 1950. The disease is prevalent in Khongisland, the Mekong River in Laos. It was officially named as schistosomemekongi in 1978. The eggs in the water enter the snail and develop into a scorpion in the snail. The cercaria escapes from the snail, especially in the morning, and the final host infects the cercaria by contact with the infected water. The cercaria entering the human body can reach various organ tissues through the blood circulation system of the human body, causing lesions. The main clinical symptoms of this disease are fever, hepatosplenomegaly, abdominal pain, diarrhea and so on. basic knowledge Sickness ratio: 0.0001% Susceptible people: no special people Mode of infection: digestive tract spread Complications: liver fibrosis shock ascites hepatic encephalopathy cirrhosis primary peritonitis sepsis acute appendicitis abscess incomplete intestinal obstruction colon cancer
Cause
The cause of schistosomiasis
(1) Causes of the disease
The female worm of Schistosoma japonicum is 12~23mm long, and the ovary and egg membrane are located in the middle of 1/5. The uterus contains eggs, the eggs are round, 40~45m in diameter, and there is a small knot at the proximal end of the egg shell. The male is long. 15 ~ 40mm, there are 7 testicles, the female ditch extends from the head to the end, the body surface is thorny, the schistosomiasis parasitized in the mesenteric vein, the life history is similar to Schistosoma japonicum, but with the following differences:
1 The eggs are small and round;
The middle host of the snail is the open snail of the Neotricula, which is a small snail of 3mm × 2mm. It lives in the water, not amphibious;
3 The incubation period from cercaria infection to adult spawning is longer, 35 days for mice; 43 to 49 days for dogs and hamsters, and 30 to 26 days for mice to vaccinate in mice, which is not easy for rabbits to schistosomiasis. sense.
The new snails are divided into three types: , and . The medium is mainly . There are 3 big black spots on the snail shell. Therefore, it is also known as the tiger snail. When the water level in the Mekong River is high, the snail is adsorbed at the bottom of the river. Under the stone; when the water level is low in the dry season, it is abundant in the shallow water of the river, and it is adsorbed on the rocks, rocks and branches, and the tail scorpion escapes from the screw, especially in the morning.
(two) pathogenesis
The early pathological changes of schistosomiasis are mainly caused by its eggs. The granuloma of Schistosoma japonicum has been proved to be a delayed type of cell-mediated allergic reaction. The antigen-sensitized T cells are released by various lymphokine factors. The immunopathological changes of schistosomiasis are more complicated. Due to the accumulation of a large number of eggs in the tissues, the granuloma formed is larger and the surrounding cells are more infiltrated. Many, and the cell composition is different from the granuloma of Schistosoma mansoni. In the early lesions, there are a large number of monocytes (plasma cells) and neutrophil infiltration, and high concentrations can be detected in the granuloma of Schistosoma japonicum. Soluble egg antigen, an eosinophilic radiation-like stick around the egg, an immune complex that binds the antigen to the antibody, called Hoeplli phenomenon, and the positive rate of circulating immune complexes and heterophilic antibodies detected in the blood of patients with acute schistosomiasis Very high, so acute schistosomiasis is a mixed manifestation of cellular and humoral immune responses; and immunopathological changes in chronic and advanced schistosomiasis were thought to belong to late-onset cell changes. State response, recently thought to be mainly due to cytokine network disorder, schistosomiasis caused by liver fibrosis is produced on the basis of granuloma, soluble egg factor, macrophage and T cells both produce fibroblast stimulation factor, prompting Fibroblast proliferation and collagen synthesis, schistosomiasis fibrosis collagen type is mainly type I, III, late schistosomiasis liver collagen is mainly type I, type I collagen fiber inter-fork connection is strong, constitutes irreversible coarse fiber bundle, and III Collagen is a fine fiber that is easily degraded by collagenase. In addition, fibronetin and laminin in the extracellular matrix are non-collagen glycoproteins, and fibronectin mediates fibroblasts and collagen. Proteins combine to form a connective tissue matrix, while laminin complements the adhesion of fibronectin.
Part of the immunity can be obtained after the human body is infected with schistosomiasis. This is a kind of concomitant immunity, that is, there are still adult parasites and spawning in the portal vein of the patient, but there is certain immunity to reinfection, and this immunity does not damage the adult body in the body. It has been proved that the surface of the schistosomiasis cortex is covered with host antigen. Because it has antigenic camouflage and escapes the immune attack, it can be parasitized for a long time. Animal experiments prove that the resistance to reinfection of cercariae cercariae depends on the body fluid immunity. In addition to antibodies, the main effector cells are eosinophils, which synergistically kill larvae that invade the skin and are therefore antibody-dependent eosinophil-mediated cytotoxicity.
Prevention
Measles schistosomiasis prevention
In the popular area of the General Survey, timely and thorough treatment of patients and infected animals. Use niclosamide to eliminate snails; properly handle the excretion of human living organisms to avoid polluting water sources; personal protection should avoid contact with infected water, it is difficult to avoid wearing long-term rubber boots when exposed to infected water, for contact with infected water Prophylactic drugs such as artesunate should be taken promptly.
Complication
Measles schistosomiasis complications Complications liver fibrosis shock ascites hepatic encephalopathy cirrhosis primary peritonitis sepsis acute appendicitis abscess incomplete intestinal obstruction colon cancer
1. Hepatic fibrosis complications
Patients with advanced schistosomiasis complicated by lower esophageal varices or more than 2/3 of the varices, and variceal rupture caused by upper gastrointestinal bleeding accounted for 16.5% to 31.6%, which is the main complication of schistosomiasis fibrosis, the clinical symptoms are a large number of Hematemesis and black feces can cause blood pressure drop and hemorrhagic shock, the mortality rate is about 15%, about half of the patients have repeated hemorrhage history, ascites or hepatic encephalopathy can occur after massive hemorrhage of the upper digestive tract, hepatic encephalopathy in the late stage Schistosomiasis is less than portal vein and cirrhosis after necrosis. Domestic reports account for 1.6% to 5.4%, and its course of disease is also longer. In addition, advanced schistosomiasis ascites complicated with primary peritonitis and Gram-negative bacilli sepsis are not. Rare.
2. Intestinal complications
In patients with endemic areas, the schistosomiasis can be found in the appendix specimens up to 31%, which is often a cause of acute appendicitis, and the appendix is easier to wear, and can be complicated by peritonitis or localized abscess.
Intestinal stenosis caused by schistosomiasis caused by severe colonic lesions may be complicated by incomplete intestinal obstruction, which is located in the sigmoid colon and rectum. In addition, mesenteric and omental lesions may adhere to a mass, forming an intra-abdominal mass, schistosomiasis Colonic granuloma can be complicated by colon cancer. The patients are younger, mostly adenocarcinoma, with a lower degree of malignancy and a later metastasis.
Symptom
Symptoms of schistosomiasis common symptoms ascites hepatosplenomegaly varicose veins
The main complications of schistosomiasis fibrosis are a large number of hematemesis and black feces, which can cause blood pressure drop and hemorrhagic shock, and the mortality rate is about 15%. About half of the patients had a history of repeated major bleeding. Ascites or concurrent hepatic encephalopathy may occur after massive bleeding of the upper digestive tract. Hepatic encephalopathy has less schistosomiasis than portal vein and necrosis, and domestic reports account for 1.6% to 5.4%, and its course is longer. In addition, advanced schistosomiasis ascites complicated with primary peritonitis and Gram-negative bacilli Septic patients are not uncommon.
Examine
Examination of schistosomiasis
Blood picture
The blood picture of patients with acute schistosomiasis is characterized by a significant increase in eosinophils. The total number of white blood cells is between (10 ~ 30) × 10 9 / L, eosinophils generally account for 20% ~ 40%, up to 90%, but Eosinophils in patients with extremely severe acute schistosomiasis often do not increase or even disappear. Instead, neutrophils increase, chronic eosinophils are still slightly increased, and late stage is due to hypersplenism, white blood cells and platelets. Reduced and have varying degrees of anemia.
2. Liver function test
In patients with acute schistosomiasis, the serum globulin is significantly increased, serum alanine transaminase (ALT) is also slightly increased, and in advanced patients, serum protein is significantly reduced due to liver fibrosis or cirrhosis, and the ratio of albumin to globulin is often reversed. Phenomenon, liver function tests of chronic schistosomiasis, especially asymptomatic patients, are mostly normal.
3.B type ultrasonic inspection
The degree of liver fibrosis can be judged from the B-ultrasound image, showing that the echogenic band of the portal vein is enhanced (6 mm): it is linear in the shape of the line; the tube is moderate; the mesh is the separator, the latter is combined with the image. The liver surface nodules and spleen enlargement may indicate liver fibrosis.
4.CT scan
In the patients with advanced schistosomiasis, the liver capsule and the intrahepatic portal vein often have calcification. The CT scan shows a more specific phenomenon; the liver capsule is thickened and calcified, perpendicular to the intrahepatic calcification septum; at the junction of the two, there is a notch formation. Severe liver fibrosis can be expressed as a turtle-like image.
Diagnosis
Diagnosis and identification of schistosomiasis
An aldehyde ether method in which fecal eggs are concentrated, or a donkey hatching method can be used.
Acute schistosomiasis is misdiagnosed as typhoid fever, amoebic liver abscess, miliary tuberculosis, etc., and significant increase in eosinophils in blood has important differential diagnostic value. It cannot be ignored. Chronic schistosomiasis liver splenomegaly should be associated with no jaundice virus. Identification of sexual hepatitis, the latter's loss of appetite, fatigue, liver pain and liver function impairment are more obvious, acute and a few patients with chronic schistosomiasis may have false positive HBsAg (RPHA method), and related to heterophilic antibodies, so serum should be checked at the same time Other hepatitis B signs or not using RPHA method, schistosomiasis patients have diarrhea, blood in the feces of stools are positive, and the number of hairy mites is more, easy to distinguish from amoebic dysentery, chronic dysentery, advanced schistosomiasis and portal vein And the identification of liver cirrhosis after necrosis: the former often has chronic diarrhea and blood history, portal vein hypertension caused by splenomegaly and lower esophageal varices are more common, liver function damage is lighter, jaundice, spider mites and liver palm are less common, but still need It can be identified by relying on multiple pathogens and immunological tests. It should be noted that schistosomiasis with hepatitis B in the endemic area is more common in China. See, in addition, in patients with epilepsy in endemic areas should be possible except brain schistosomiasis.
