Fascioliasis

Introduction to schistosomiasis Fascioliasis is caused by fasciolahepatica and fasciolagigantica in the hepatic bile duct of a herbivorous mammal, or the human body to cause parasitic diseases. It is cattle, sheep, etc. One of the serious parasitic diseases of animals, the infection rate is as high as 20% to 60%, which seriously endangers the development of animal husbandry. The selection of the final host is not strict, the human body is not a suitable host, so the ectopic parasitis is more, the clinical manifestations are more complex and diverse, and more serious, mainly caused by the acute phase of the larvae in the abdominal cavity and liver and the bile duct caused by adults. Chronic phase manifestations of inflammation and hyperplasia. basic knowledge The proportion of illness: 0.005% Susceptible people: no special people Mode of transmission: spread by parasites Complications: jaundice, liver cirrhosis, anemia

Cause of schistosomiasis

Environmental factors (75%):

If you do not pay attention to the hygiene of daily life, the contact with the eggs will not be cleaned and disinfected in time, resulting in infection.

Dietary factors (25%):

Ingest foods contaminated with adults or eggs, edible resources such as water sources, or fail to eliminate contaminated eggs.

Life history of Fasciola hepatica: Adults lay eggs in the end-host hepatic bile duct, enter the intestine with bile, excrete in the feces, excrete in the water at 22 ~ 26 ° C, develop into hairy eggs after 9 to 14 days, and quickly Drilling into the cone snail, developing into a scorpion through the cellulite and thunder in the snail, then escaping from the snail, floating under the water surface, and then removing the tail after contacting the animal body (plant or saprophytic organism) The capsule is attached to an object in the water (such as water grass), and its shape resembles a straw hat. When the host eats aquatic plants containing cystic mites, the cystic sac is released from the small intestine digestive juice, and then escapes into a cercaria. Into the abdominal cavity to develop into a child worm, in the abdominal cavity for about 48h, the child worm breaks through the liver capsule into the liver parenchyma, continues to develop with the liver tissue as a nutrient, swims in the liver for about 6 weeks and finally enters the hepatic bile duct parasitism, about 4 The week develops into an adult (Fig. 1). From the infected sac to the feces, the eggs are found. The shortest is 10 to 11 weeks. Each adult can lay about 20,000 eggs per day. The adult life span can reach 12 years.

Pathogenesis

The damage of the liver fluke to the human body can be roughly divided into two aspects: the child and the adult. The early childhood insects pass through the intestinal wall and enter the abdominal cavity. In the process, the tissue can be destroyed, and the hemorrhage remains on the insect path. The child is in the liver parenchyma. When moving, hepatocytes are used as food to damage liver tissue. With the development of children's worms, liver damage is more extensive, and fibrinous peritonitis may appear. The liver is obviously congested with the milk, and the milky white pattern (hard knot) is mirrored. The liver lesions were found to be filled with hepatocyte debris, eosinophils, neutrophils, lymphocytes and macrophages. There were occasional small abscesses on the surface of the liver tissue, and the abscess was filled with eosinophils and a large amount of summer-ray crystals. After about 6 weeks of swimming in the liver, the worm enters the bile duct and develops into an adult worm. The adult parasitizes in the bile duct, causing the lumen to increase significantly, protruding from the surface, the suction of the worm body and the mechanical stimulation of the skin spine. Causes inflammatory changes, and is prone to secondary infections leading to cell cholangitis or liver abscess, the body can produce a large amount of proline, can induce bile duct epithelial hyperplasia, so the main lesion caused by adults is gallbladder Tube inflammation and epithelial hyperplasia, resulting in narrowing of the bile duct lumen, thickening of the wall, fibrous tissue hyperplasia around the bile duct, severe cases of large bile ducts also have chronic obstruction and cholestasis, resulting in biliary cirrhosis.

Schistosomiasis prevention

Strengthen livestock management, graze in areas, avoid pollution of water sources, separate drinking water (including livestock) from general water use, disinfect water should be disinfected regularly, strengthen health education, and do not drink or eat raw water and aquatic plants that may be contaminated to cut off way for spreading.

Meteoric complication Complications jaundice liver cirrhosis anemia

Blockage of the worm causes cholestasis, jaundice and biliary colic; enlarged bile duct compression can cause liver tissue atrophy and necrosis, and further cirrhosis occurs. In chronic critically ill patients, chronic anemia can cause severe anemia.

Symptoms of schistosomiasis common symptoms ascites constipation bacterial infection diarrhea abdominal pain jaundice congestion biliary cirrhosis chest pain bloating

The incubation period varies from day to day to 2 to 3 months. Clinically, it can be divided into acute phase, chronic phase and ectopic lesions.

Acute phase

Symptoms mainly caused by the migration of children's worms in the abdominal cavity and liver, such as combined with bacterial infections, can lead to serious consequences. The symptoms and signs in this period are not exactly the same, mainly irregular fever (38 ~ 40 ° C), right lower abdominal pain, Loss of appetite, bloating, diarrhea or constipation, there may be cough, chest pain, right chest smell and wet voice and pleural friction sound, most of them have large liver, a few with splenomegaly and ascites, the above symptoms can last for about 4 months Regressed and gradually entered the chronic phase.

2. Chronic phase

When the acute symptoms subsided, there may be no obvious discomfort for several months or years, and some symptoms may reappear during this period, such as abdominal pain, diarrhea, irregular fever and repeated urticaria, jaundice, anemia, low albumin, high immunity. Globulinemia, the latter two are due to parasitic biliary epithelial damage, erosion and adult blood (each caused by blood loss of about 0.5ml / d), due to adult bile duct chronic inflammation and hyperplasia, resulting in bile duct Fibrosis leads to cirrhosis of the liver, or it can be formed by adult or bile duct stones, causing obstructive jaundice caused by obstruction of the bile duct, and then developing into biliary cirrhosis.

3. Ectopic damage

Also known as extrahepatic hepatic schistosomiasis, the child worms move through the abdominal cavity or are brought to the organs and tissues other than the liver, such as the abdominal wall muscles, causing lesions. Individuals in the Middle East have the habit of eating raw goat liver. The parasitic parasites in the liver and bile ducts can invade the human pharynx, causing local edema and congestion, swallowing and breathing difficulties, deafness and asphyxia, etc., that is, pharyngeal hepatic schistosomiasis.

Examination of schistosomiasis

Blood routine

Leukocytes and eosinophils increased significantly, especially in the acute phase, white blood cells usually (10 ~ 43) × 10 ⁹ / L, eosinophils up to 0.79, erythrocyte sedimentation rate, up to 164mm / h, hemoglobin Mostly 70 to 110g / L, but also lower.

2. Liver function test

Acute liver function has different degrees of abnormalities, ALT, AST increased, serum bilirubin increased, albumin decreased, globulin increased to 51 ~ 81g / L, albumin / globulin (A / G) ratio inverted , IgG, IgM and IgM are elevated, while IgA is normal.

3. Pathogen examination

The positive result of the pathogen test is the basis for the diagnosis. However, the eggs are often not detected in the early stage of the acute phase. Generally, it can be found 2 to 3 months after the infection. The washing and sedimentation method can be used to improve the Kato method or the mercury-aldehyde. Iodine concentration method is used to check the eggs from the feces, and the duodenal drainage liquid is precipitated or centrifuged for examination, and the positive rate is high.

Exploratory laparotomy found adult or eggs in the bile duct, laparoscopic biopsy or other histopathological examination found that the worm or eggs can be used as a basis for diagnosis.

4. Immunological examination

Serum immunological examination can be performed with soluble protein antigen of the worm, and the method can be selected by enzyme-linked immunosorbent assay (ELISA), indirect fluorescent antibody test (IFA), indirect hemagglutination test (IHA), convective immunoelectrophoresis (CIE), etc. The test results cross-react with other trematode infections, but they are still of great diagnostic significance when the eggs are not detected early in the infection. For example, the detection of circulating antigens in the serum of Fasciola hepatica is more valuable than the detection antibody. The flukes of Fasciola hepatica in the patient's stool are positive at the 6th week after infection and have early diagnostic significance.

5. Ascites examination

The ascites is grass yellow, and the number of cells is above 1000×106/L, mainly eosinophils.

Film degree exam:

Ultrasound examination

Ultrasound examination of the liver can be seen in the biliary tract. The flukes of the liver fluke are 0.3-0.5 cm round shadow, which is like the "Olympic Ring". When the abdomen is percussed, the shadow can move.

2. CT examination

A "pseudo-hepatic tumor" can occur.

3. Cholangiography

At different angles of cholangiography, the shadows of the worms are different. The lateral view is a slender, curly rope. The other angles can be seen as narrow circular shadows or false wall defects.

Diagnosis and identification of schistosomiasis

diagnosis

There are raw medical aquatic plants and drinking water history and the above clinical symptoms, white blood cells and eosinophils increased significantly, erythrocyte sedimentation rate increased, anemia, ALT and AST activity increased, chronic serum bilirubin increased, albumin / globulin ( A / G) ratio is reversed, should consider hepatic schistosomiasis, found eggs in the feces, laparotomy, laparoscopic biopsy or other histopathological examination found that adults or eggs can be used as a basis for diagnosis, but generally after infection 2 In March, the eggs can be found from the feces, and the immunological examination has important diagnostic significance when the eggs are not detected in the early stage of infection.

Differential diagnosis

Hepatic schistosomiasis should be associated with clonorchiasis, post-test schistosomiasis, ginger schistosomiasis, paragonimiasis, amoebic or bacterial liver abscess, liver hydatid disease, cholecystitis caused by various causes , cholangitis and cholelithiasis, liver cancer and other liver and gallbladder diseases.

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