Overview of the disease
Schistosomiasis is a parasitic disease caused by Schistosoma cruzi parasitizing the bile ducts of the human liver. Humans are often infected by eating uncooked freshwater fish or shrimp containing the cystic larvae of Schistosoma cruzi. Mildly infected patients may be asymptomatic, while severely infected patients may present with clinical symptoms such as dyspepsia, epigastric pain, diarrhea, depression, and liver enlargement, and in severe cases, complications such as cholangitis, gallstones, and cirrhosis of the liver may occur.
Causes
Schistosoma oryzae is a hermaphroditic trematode. Its life history is complex, according to the developmental program can be divided into adult worms, eggs, microfilariae, cystic larvae, microfilariae, caecal larvae, cystic larvae and larvae and other eight stages. Adult parasites are found in the intrahepatic bile duct system, especially in the branches of the bile ducts. Occasionally, they can also be found in the pancreatic duct. Adult worms have a long, narrow, flat and thin body, with a thin, pointed front end and a blunt, rounded back end, resembling a sunflower seed. The body surface has no spines and is brown and translucent. The size of the body is (10~25)mm×(3~5)mm, with two suckers in the mouth and abdomen, and the digestive organs are mouth, pharynx, esophagus and branching intestinal tubes. The digestive organs include mouth, pharynx, esophagus and branching intestinal tubes. The reproductive organs are hermaphroditic, with both testes branching and arranged at the posterior end of the body.
Humans are often infected by consuming uncooked freshwater fish or shrimp containing the cystic larvae of Schistosoma oryzae. Mild infection may be asymptomatic, while severe infection may present with dyspepsia, epigastric tenderness, diarrhea, depression, hepatomegaly, and other clinical manifestations, and in severe cases cholangitis, gallstones, and cirrhosis may occur. Children with severe infection often have significant malnutrition and growth disorders.
Symptoms
The disease usually starts slowly, and only a few patients with severe infection in a short period of time have an acute clinical onset. Mildly infected patients are often asymptomatic or only experience epigastric fullness, lack of appetite, or mild abdominal pain after eating. Patients are easily fatigued. Eggs may be detected in the feces. More severely infected patients usually have a slower onset of disease, with lack of appetite, epigastric fullness, mild diarrhea, and vague pain in the liver region. Patients may have hepatomegaly, which is evident in the left lobe, with pressure and percussion pain. It may be accompanied by neurasthenia symptoms such as dizziness, insomnia, fatigue, dysphoria, palpitation and memory loss.
Individual patients develop obstructive jaundice and even biliary colic due to blockage of the common bile duct by a large number of adult worms. When severe cases of chronic repeated infection develop into cirrhosis and portal hypertension, emaciation, anemia, abdominal wall varicose veins, hepatosplenomegaly, ascites, jaundice and so on occur. Severe infected children may present with malnutrition and growth disorders and may even cause dwarfism. Severe infections can often present an acute onset. The incubation period is short, only 15-26 days. Patients have sudden chills and high fever of 39℃ or more, with flaccid fever. Lack of appetite, anorexia of greasy food, hepatomegaly with tenderness, mild jaundice, and splenomegaly in a few cases. After a few weeks, the acute symptoms disappear and enter the chronic phase, manifested by fatigue, dyspepsia, hepatomegaly with pressure pain.
Chinese branch testicular schistosomiasis symptoms vary in severity, generally can be divided into three degrees: ① Mild: no self-awareness of symptoms, only in the fecal examination found eggs. Or there are mild gastrointestinal symptoms, such as pressure and pain in the stomach after eating, soft stools and so on. It accounts for about 35%. ② Moderate: mainly with more obvious gastrointestinal symptoms, such as lack of appetite, dyspepsia, distension and pain in the right upper abdomen, hepatomegaly, mild edema. If complicated by bacterial infection, cholangitis and cholecystitis may occur. It accounts for about 55%. (iii) Severe: obvious gastrointestinal symptoms, recurrent diarrhea or constipation, right upper abdominal pain or splenomegaly, ascites, anemia, etc.. Mostly seen in children, accounting for about 10%.
The same patient may have several of the above clinical types coexisting. In addition, a very small number of patients from non-endemic areas who are infected for the first time with a large number of infections may have a sudden onset of chills, high fever, distension and pain in the middle-upper or right-upper abdomen, hepatomegaly with tenderness, mild jaundice, and splenomegaly about 1 month after infection. Blood eosinophils are significantly increased. Very few patients have a leukemia-like reaction. Acute symptoms disappear after a few weeks, while dyspepsia, malaise and hepatomegaly remain.
Examination
1. Blood tests
Acute patients may have increased white blood cell count and eosinophilia. Severe infected patients may also have eosinophilic leukemia-like reaction, with white blood cell count up to 50×109/L and eosinophilic count up to 60% or more. Chronic patients may be mildly anemic, with a normal or mildly increased total leukocyte count and a mild increase in eosinophils in most cases (5% to 10%). Blood sedimentation is accelerated, and serum alkaline phosphatase, alanine aminotransferase and gamma-glutamyl transpeptidase activity are increased. Plasma total protein and clear protein decrease.
2. Immunologic examination
Intradermal test, indirect hemagglutination test, convective immunoelectrophoresis test, enzyme-linked immunosorbent assay, indirect fluorescent antibody test, etc. have been tried to assist in the diagnosis of Chinese testicular schistosomiasis, but the test results are different, and other gastrointestinal parasitic infections (especially trematode infections) have more obvious cross-reaction, can not be used as a confirmation of the diagnosis, and is now used only as a preliminary screening of epidemiological investigation. In recent years, some scholars have tried sandwich enzyme-linked immunosorbent assay to detect circulating antigens, and its sensitivity and specificity are better than that of circulating antibody detection.
3. Parasitological examination
(1) fecal examination ① direct smear method is easy to operate, the disadvantage is that in the mildly infected, the eggs in the feces are very few, it is not easy to detect, usually more than a few smears in order to improve the detection rate. ② precipitation egg collection method can be precipitated with water, because the eggs are heavy and small, so this method is applicable. Can also be precipitated with water and then centrifuged, can also be treated with ether hydrochloride and then centrifuged, so that the eggs are concentrated on the tip of the centrifugal precipitation tube and easy to detect. (3) Sodium hydroxide digestion method can be used as egg counting method, take 1g of feces, put it in the centrifugal sedimentation tube with 5% sodium hydroxide solution, stir well, after 1 hour of digestion, stir well with the counting tube of the Division and suck 0.075 ml of smear, count the eggs of the whole slice under the microscope, and then multiply it by 80, i.e., it is the number of eggs contained in each gram of feces.
(2) Bile or duodenal fluid examination The detection rate of eggs is greatly improved when duodenal fluid, especially bile, is removed by duodenal drainage. Because the eggs are directly discharged from the bile duct into the duodenum, the eggs are most abundant in the bile and are easily detected without mixing with debris. Precipitation and concentration of the entire bile drained for egg detection has been shown to have a higher positive rate. In addition, adult worms have also been found in biliary surgery, in biliary drainage tubes, or in puncture tubes or tissue blocks of hepatic puncture, all of which can help to clarify the diagnosis.
4. Imaging examination
(1) Ultrasound When B-type ultrasound is used to examine the patients with Chinese testicular schistosomiasis, it can be seen that the light spots in the liver are coarse and dense and uneven, with small patches or clusters of echoes, and the diffuse middle and small bile ducts are dilated to different degrees, and the walls of the bile ducts are rough, thickened and echoes are strengthened.
(2) CT examination shows that the intrahepatic bile ducts are uniformly dilated from the hepatic hilar to the periphery, and the extrahepatic bile ducts are not obviously dilated; intrahepatic tubular dilatation, the ratio of bile ducts’ diameter to their lengths is more often than not less than 1:10; cystic dilatation of bile ducts is mainly distributed around the periphery of the liver, and the ducts are of similar sizes. In a few cases, irregular tissue mass can be seen in the gallbladder.
Diagnosis
Diagnosis is made on the basis of etiology, history, clinical manifestations and laboratory tests.
Treatment
General treatment should first give symptomatic and supportive therapies to patients with severe disease, such as increasing nutrition, correcting anemia, diuretic and reducing swelling, etc., and then carry out anthelmintic treatment after the systemic condition improves. In a few cases, due to a large number of infections, chills, high fever, pain in the liver area and mild jaundice, elevated blood aminotransferases, blood eosinophils increased significantly and other symptoms of acute Chinese testicular schistosomiasis.
1.Pathogen treatment
(1) Praziquantel is the drug of choice for the treatment of this disease, which has the advantages of short course of treatment, high efficacy, low toxicity, mild reaction and fast absorption, metabolism and excretion in the body. It should be taken for 2 days in a row. The negative rate of fecal worm eggs reaches more than 90% in 3 months after treatment. A few cases of dizziness, headache, fatigue, nausea, abdominal pain, diarrhea and other adverse reactions, which can be alleviated or disappeared after 24 hours. The general therapeutic dose has no significant damage to the liver and kidney. Individual patients may have preterm contraction, arrhythmia and so on.
(2) Albendazole In recent years, clinical application of albendazole in the treatment of this disease, the effect is satisfactory. It should be taken in 2 times, 7 days as a course of treatment. The negative rate of fecal worm eggs is almost 100%.
2. Symptomatic treatment
For those with severe infection and heavy malnutrition or cirrhosis, nutrition should be strengthened, anemia should be corrected, liver should be protected to improve the general condition, and deworming treatment should be carried out in time. For those with concurrent cholecystitis and cholangitis, in addition to deworming, antibacterial drugs should be added. For acute cholecystitis, cholelithiasis and obstruction of common bile duct, surgery should be performed. When combined with viral hepatitis, in addition to actively protecting the liver, deworming treatment should be carried out as soon as possible on the basis of the improvement of the condition.
Prevention
Vigorously do a good job of hygiene publicity and education work to improve the public’s understanding of the transmission of this disease, consciously do not eat raw or undercooked fish and shrimp. Improve cooking methods and change eating habits, and pay attention to the separate use of kitchen knives, cutting boards and utensils for cutting raw and cooked food. Do not feed raw fish to cats and dogs.
Active treatment of patients and infected persons is a positive measure to protect people’s health and reduce the source of infection.
Reasonable disposal of feces and changing the habit of fish farming are important measures to prevent the transmission of Chinese testicular schistosomiasis. In addition, combining the needs of production, cleaning pond mud and disinfecting fish ponds are effective in killing snails.