Clonorchiasis

　　Clonorchis sinensis is a hermaphroditic trematode. Its life cycle is complex and can be divided into eight stages: adults, eggs, miracidia, sporocysts, rediae, cercariae, metacercariae, and larvae. Adults parasitize the intrahepatic bile duct system, particularly in the branching parts of the bile ducts. They may also be found in the pancreatic ducts occasionally. The adult body is narrow, elongated, flattened, with a pointed anterior end and a bluntly rounded posterior end, resembling the kernel of a melon seed. The body surface is smooth and translucent, brown in color. The size is approximately (10-25) mm × (3-5) mm, with two oral and ventral suckers, and the digestive organs include the mouth, pharynx, esophagus, and branched intestines. The reproductive organs are hermaphroditic, with two testes that are branched and arranged at the posterior end of the body.

　　Humans are commonly infected by consuming freshwater fish or shrimp that are not properly cooked and contain Clonorchis sinensis metacercariae. Lightly infected individuals may not show any symptoms, while severely infected individuals may present with symptoms such as dyspepsia, upper abdominal pain, diarrhea, lack of vitality, and enlarged liver. Severe cases may develop complications such as cholangitis, gallstones, and liver cirrhosis. Children with severe infections often suffer from significant malnutrition and growth and development disorders.

　　Clonorchiasis can lead to complications such as acute cholecystitis, cholangitis, cholelithiasis, liver cirrhosis, and leukemoid reaction, among others. The specific complications are described as follows.

　　1. Cholecystitis, cholangitis, cholelithiasis:Clonorchis sinensis adults and eggs can cause biliary obstruction, and the mechanical injury caused by the adults can lead to the shedding of bile duct epithelium, making it susceptible to secondary bacterial infection, which can trigger acute cholecystitis, cholangitis, cholelithiasis, and the appearance of corresponding clinical symptoms.

　　Second, liver cirrhosis:According to reported data, the incidence of liver cirrhosis due to Clonorchis sinensis infection is about 0.55%. Clinical manifestations may include liver enlargement (mainly in the left lobe) and reduced liver function, portal hypertension, and other symptoms. If liver cirrhosis associated with Clonorchis sinensis infection can be diagnosed and treated early, the prognosis is good.

　　Third, liver cancer:According to statistics (2000 people in the same area), about 0.72% of Clonorchis sinensis patients have biliary tract cell cancer, and about 2.12% have hepatocellular cancer.

　　Fourth, leukemoid reaction:Infection can stimulate the host's bone marrow granulocytes to proliferate in large numbers, resulting in a leukemoid reaction, with white blood cells up to 150,000. Bone marrow puncture examination shows the bone marrow picture of increased acidophilic granulocytes syndrome. After deworming treatment, it can return to normal.

　　Fifth, ectopic parasitism and ectopic damage: Clonorchis sinensis can parasitize in other organs of the host besides the liver, increasing the complexity and diagnostic difficulty of the disease.

　　1. Pancreatic Clonorchis sinensis infection: Commonly accompanied by liver and biliary Clonorchis sinensis infection. Clinically, it often manifests as acute or chronic pancreatitis, cholangitis, cholecystitis, and other diseases.

　　2. Pulmonary Clonorchis sinensis infection: Extremely rare, mainly manifested as fever, dyspnea, cough, and diagnosis mainly relies on the detection of eggs in sputum, bronchial brush or feces.

　　Clonorchis sinensis infection generally has a slow onset, and only a few patients with short-term severe infection present with acute onset clinically. The specific clinical manifestations of acute and chronic Clonorchis sinensis infection are described as follows.

　　First, acute Clonorchis sinensis infection

　　1. Incubation period:5-40 days, usually 30 days.

　　2. Fever:The highest body temperature can reach above 39℃, often accompanied by chills and rigor. The fever pattern is irregular, and the duration of fever varies.

　　3. Abdominal pain and diarrhea:Most patients present with upper abdominal pain as the initial symptom, which resembles acute cholecystitis.

　　4. Liver area pain and liver enlargement:Mainly characterized by the enlargement of the left lobe of the liver, often accompanied by marked tenderness, mainly related to intrahepatic bile duct inflammation.

　　5. Allergic symptoms:The most common symptoms include urticaria and increased acidophilic cells in peripheral blood, and in severe cases, there may be a leukemoid reaction dominated by increased acidophilic granulocytes.

　　Second, chronic Clonorchis sinensis infection

　　1. Clinical manifestations: Repeated multiple small infections or failure to receive timely treatment during the acute phase can all evolve into chronic Clonorchis sinensis infection. Acute phase symptoms are often present in the medical history. Chronic Clonorchis sinensis infection is the most common, generally with concealed disease and complex symptoms. There are also cases with no obvious clinical symptoms but with variceal bleeding due to liver cirrhosis as the initial symptom. Clinically, chronic Clonorchis sinensis infection can be divided into mild, moderate, and severe degrees.

　　Chronic infectors can have complications such as cholecystitis, bile pigment gallstones, obstructive jaundice, and primary biliary tract cellular liver cancer.

　　2. Clinical classification

　　(1) Hepatitis type:Accounts for about 40.2% of the total number of patients, with clinical manifestations mainly including liver enlargement, pain in the liver area, fatigue, decreased appetite, and some patients have elevated serum alanine aminotransferase levels.

　　(2) Asymptomatic type:About 34.6% of the total number of patients, without obvious symptoms.

　　(3) Dyspepsia type:About 16.1% of the total number of patients, clinical manifestations are mainly abdominal pain, abdominal distension, intermittent diarrhea, and liver enlargement.

　　(4) Cholecystitis and choledochitis type:About 6.34% of the total number of patients, with a history of cholecystitis, recurrent attacks, liver enlargement, with jaundice and fever.

　　(5) Nervous weakness type:About 2.12% of the total number of patients, clinical manifestations include headache, insomnia, decreased memory, fatigue, etc.

　　(6) Liver cirrhosis type: About 0.56% of the total number of patients, manifested as liver and spleen enlargement, ascites, hyperfunction of the spleen, etc.

　　(7) Dwarf type:About 0.06% of the total number of patients, manifested as growth and development disorders, without affecting intelligence.

　　Clonorchiasis is caused by eating freshwater fish or shrimp infected with Clonorchis sinensis cysticercus, either raw or undercooked. The key to prevention is to cut off the transmission route, control oral infection, and also pay attention to controlling the infectious source. The specific preventive and control measures are described as follows.

　　First, measures for the infectious source

　　1. General investigation and treatment of infectious sources:In epidemic areas, it is necessary to strengthen the investigation and treatment of infectious sources. Skin tests can be used for screening first, and then stool tests can be performed on positive cases. Individuals with positive stool tests for ova should be given medical treatment.

　　2. Management of animal infectious sources:Do not feed raw fish, shrimp, or fish viscera to cats, dogs, pigs, etc., to avoid infection. The feces of these livestock also need to be managed, and feces should not enter ditches and fish ponds. Livestock with infected individuals should also be dewormed if possible. Wild animals as reservoir hosts should be killed according to the situation.

　　Second, measures for the transmission route

　　1. Do not eat uncooked fish or shrimp:Strengthen health education and publicity work to make residents in the epidemic area aware of the hazards and transmission routes of the disease. Not eating uncooked fish or shrimp is the most effective measure to prevent the disease. The cysticercus in 1mm thick fish meat will die after being immersed in 98℃ hot water for 1 second, and will die after 5 seconds at 70℃. If the fish meat containing cysticercus is 2-3mm thick, it will take 8 seconds to die in 70℃ water. Therefore, the thicker the fish meat, the longer the heating time required, and the stronger the resistance of the cysticercus to seasonings. In vinegar (containing about 3.36% acetic acid), it will take 2 hours to die; in soy sauce (containing 19.3% sodium chloride), it will take 5 hours to die. Therefore, all uncooked fish meat has the potential to transmit the disease, and attention must be paid to separating raw and cooked food in the kitchen, such as separate cutting boards and knives. Children should be educated not to eat grilled fish, baked fish, fried fish, or dried fish.

　　2. Strengthen the management of feces:Do not allow untreated feces to enter fish ponds, and do not build toilets on fish ponds or use untreated feces as fish feed.

　　The transmission cycle of Clonorchis sinensis is relatively clear. As long as we grasp the main link of cutting off the transmission route and control the infectious source, the spread of the disease can be prevented.

　　The examination of Clonorchis sinensis includes blood examination, immunological examination, parasitological examination, and imaging examination, with specific examination methods as described below.

　　One, Blood examination

　　Acute patients may have an increased white blood cell count and an increase in eosinophils. Severe cases may also show eosinophilic leukemia-like reactions, with white blood cells reaching 50×10^9/L, and eosinophils reaching more than 60%. Chronic patients may present with mild anemia, normal or slightly increased total white blood cell count, and most cases with a slight increase in eosinophils (up to 5% to 10%). With the extension of the course of the disease, patients may have varying degrees of anemia, with most white blood cell counts normal, but an increase in eosinophils, an accelerated erythrocyte sedimentation rate, and increased activity of serum alkaline phosphatase, alanine aminotransferase, and gamma-glutamyl transpeptidase. The total protein and albumin in plasma decrease.

　　Two, Immunological examination

　　1. Detection of specific antibodies in serum.

　　2. Detection of specific antigens in serum.

　　3. Skin test.

　　Three, Parasitological examination

　　1. Feces examination

　　(1) Direct smear method The operation is simple, but the disadvantage is that in mild cases, the eggs in the feces are rarely found and difficult to detect. It is usually necessary to examine several smears to increase the detection rate.

　　(2) Sedimentation egg collection method Clear water sedimentation can be used, as the eggs are heavier and smaller, making this method applicable. It can also be centrifuged after clear water sedimentation, or it can be treated with ethyl acetate hydrochloride before centrifugation to concentrate the eggs at the tip of the glass, making them easier to detect.

　　(3) Sodium hydroxide digestion method It can also be used as a method for counting eggs, taking 1g of feces, placing it in a centrifugal sedimentation tube containing 5ml of 10% sodium hydroxide solution, thoroughly stirring, digesting for 1 hour, then mixing with a Sies counting tube and吸取0.075ml for a smear. Count all the eggs under the microscope, and then multiply by 80 to get the number of eggs per gram of feces.

　　2. Bile or duodenal fluid examination The duodenal drainage technique can be used to extract duodenal fluid, especially bile, which greatly increases the detection rate of eggs. Since the eggs are directly excreted from the bile duct into the duodenum, the bile contains the most eggs and is free of mixed debris, making it easy to detect. The sedimentation and concentration of all the bile extracted by drainage can be checked for eggs, with a higher positive rate. In addition, adult worms can also be found in biliary tract surgery, adult worms or eggs in biliary drainage tubes, or adult worms or eggs found in the needle tubes or tissue blocks during liver puncture, all of which are helpful for confirming the diagnosis.

　　Four, Imaging examination

　　1. Ultrasound When using B-ultrasound to examine patients with Clonorchis sinensis, it can be seen that the intrahepatic light points are coarse and dense with uneven distribution, with small patchy or mass-like echoes, and the bile ducts show varying degrees of diffuse expansion, with rough, thickened bile duct walls and enhanced echoes.

　　2. CT examination It can be seen that the intrahepatic bile ducts expand uniformly from the hilum to the periphery, with no obvious expansion of the extrahepatic bile ducts; the intrahepatic tubular expansion has a diameter-to-length ratio of less than 1:10; the cystic expansion of the bile ductules is mainly distributed around the liver periphery, with similar diameters. In a few cases, irregular tissue mass shadows can be seen in the gallbladder.

　　Patients with Clonorchis sinensis infection should consume high-calorie, high-protein, and acidic foods. The general population should pay attention to food selection, especially for raw foods, and the specific dietary precautions are described as follows.

　　1. With the improvement of people's living standards, traveling has become a common occurrence in life. During the travel process, we should pay attention not to eat any raw meat, and not to easily enter the water in the epidemic area for play.

　　2. When dining in restaurants in the epidemic area, it is best to choose cooked dishes. If cold dishes are chosen, it is necessary to choose restaurants with a separate cold dish operation room.

　　3. Do not eat uncooked fish and shrimp.

　　For severe cases of Clonorchis sinensis infection, symptomatic and supportive therapy should be given first, such as increasing nutrition, correcting anemia, diuresis, and edema, and deworming treatment should be carried out after the overall condition improves. A few cases may experience chills, high fever, pain in the liver area, and mild jaundice due to a single large infection, and blood tests may show elevated transaminases and significant increases in eosinophils. This disease is distributed worldwide, and it is prevalent in Guangdong, Shandong, Henan, and other 24 provinces, municipalities, and autonomous regions in China. The specific treatment methods are described as follows.

　　First, Pathogen Treatment

　　1. Praziquantel is the first-line drug for treating this disease, with advantages such as a short course, high efficacy, low toxicity, mild reactions, and rapid absorption, metabolism, and excretion in the body. It is taken for 2 consecutive days. After treatment, the rate of negative ova in feces reaches over 90% after 3 months. A few cases may experience adverse reactions such as dizziness, headache, fatigue, nausea, abdominal pain, and diarrhea during the course of taking the medicine, which can be reduced or disappear after 24 hours. The general therapeutic dose has no obvious damage to the liver and kidneys. Some patients may have premature ventricular contractions, arrhythmias, and other conditions.

　　2. Albendazole has been used clinically to treat this disease with satisfactory results in recent years. It is taken twice, with a 7-day course of treatment. The rate of negative ova in feces is almost 100%.

　　Second, Symptomatic Treatment

　　For patients with severe infection and significant malnutrition or liver cirrhosis, it is necessary to strengthen nutrition, correct anemia, protect the liver, and improve the overall condition to improve the body's condition, and carry out deworming treatment in a timely manner. For those with concurrent cholecystitis and cholangitis, in addition to deworming, antibacterial drugs should also be added. For acute cholecystitis, cholelithiasis, and common bile duct obstruction, surgical treatment should be provided. In the case of concurrent viral hepatitis, in addition to actively protecting the liver, deworming treatment should be started as soon as possible on the basis of improved condition.