Hepatitis C

　　Hepatitis C virus (HCV) is a type of hepatitis virus transmitted through blood. In 1989, Chiron Corporation in the United States successfully cloned the (HCV) cDNA using molecular cloning technology. HCV is the first human virus discovered using molecular biology techniques. HCV belongs to the family of enveloped viruses, and its biological properties and genetic structure are similar to those of flaviviruses and rhabdoviruses. It has been confirmed that HCV is a spherical particle containing a lipid envelope, with a diameter of 30-60 nm. The HCV genome is a long single-stranded positive-sense RNA, about 9.5 Kb in length. The HCV genome contains a large open reading frame (ORF) encoding a polyprotein of 3010 or 3011 amino acids. The encoded polyprotein has a distinct common structure with flaviviruses: containing structural proteins (including core protein and envelope protein) and non-structural proteins (NS1-NS5).

　　HCV infection is the fundamental cause of disease. Under the influence of external factors such as alcohol consumption, fatigue, long-term use of hepatotoxic drugs, etc., it can promote the progression of the disease. The pathological changes of hepatitis C are extremely similar to those of hepatitis B, mainly characterized by hepatocyte necrosis and lymphocyte infiltration. Chronic hepatitis can lead to the proliferation of fibrous tissue in the portal area, and severe cases can form pseudolobules, leading to liver cirrhosis.

　　Common complications of hepatitis C virus infection include arthritis, glomerulonephritis,结节性多动脉炎(nodular polyarteritis)and others. Rare complications include diabetes, fatty liver, aplastic anemia, multiple neuritis, pleurisy, myocarditis, and pericarditis, among which diabetes and fatty liver are worthy of attention. A few patients may have post-hepatitis hyperbilirubinemia.

　　The incubation period of hepatitis C virus infection is 2 to 26 weeks, with an average of 7.4 weeks. The incubation period of hepatitis C virus infection caused by blood products is short, usually 7 to 33 days, with an average of 19 days.

　　The clinical manifestations are generally milder than those of hepatitis B, mostly subclinical without jaundice. It is common to have elevated ALT, which remains high for a long time or fluctuates repeatedly. The average values of ALT and serum bilirubin in patients are low, and the duration of jaundice is short. However, there are also severe cases that are difficult to distinguish from hepatitis B clinically.

　　HCV infection is more likely to become chronic than HBV infection. Observations show that about 40% to 50% develop chronic hepatitis, 25% develop liver cirrhosis, and the rest have self-limiting courses. Chronic hepatitis C usually presents as anicteric, with long-term fluctuation of ALT that does not decrease, and persistent high titer of anti-HCV. Therefore, clinical attention should be paid to the changes in ALT and anti-HCV.

　　Although the clinical manifestations of hepatitis C are generally mild, severe hepatitis can also occur. HAV, HBV, HCV, HDV, and HEV can all cause severe hepatitis, but the background and frequency of occurrence are different. Statistical data from Europe and America show that the cause of acute and subacute severe hepatitis is HBV, while in Japan, it is HCV. The reason may be that the infection rate of HCV in the Japanese population is much higher than that in Europe and America. Secondly, the HCV genotypes in Europe and America are different from those in Japan. There is no detailed information in China. Most reports show that HBV is the most common, followed by HCV in chronic hepatitis B complicated with HCV infection.

　　The prevention of hepatitis C virus infection mainly involves preventing the pathogenic factors of hepatitis C virus infection. The specific preventive measures are as follows.

　　1. The current important measure to reduce post-transfusion hepatitis C is to screen blood donors for anti-HCV.

　　2. Manage the source of infection.

　　Isolate patients by hepatitis type, using disposable medical supplies; promote knowledge of the prevention and treatment of hepatitis C, and comply with disinfection and isolation procedures.

　　3. Cut off the route of transmission.

　　Medical devices should be disinfected after single use, and disposable medical supplies should be used; strictly control the indications for blood transfusion, plasma, and blood products; ensure the quality of blood and blood products.

　　4. Protect susceptible populations.

　　There are reports that using immunoglobulin to prevent hepatitis C is effective, with a dosage of 0.06ml/kg, administered by intramuscular injection. Ultimately, controlling this disease depends on vaccine prevention. The successful cloning of HCV has provided conditions for the vaccine prevention of the disease.

　　Most hepatitis C (HCV) infected individuals develop anti-HCV in their bodies, so detecting anti-HCV is very valuable for diagnosing hepatitis C. Positive anti-HCV is a marker of HCV infection, but the current test results cannot fully reflect acute, chronic, or recovery stage infection. The antibody titer also cannot reflect the intensity of HCV infection. At least, this has not been confirmed in animal experiments. Positive anti-HCV may indicate an immune state after recent infection, but most cases represent current HCV infection, and to some extent, reflect the individual's infectivity. The time from HCV infection to the conversion of anti-HCV varies greatly. Currently, the antibody detection is late, and during this period, patients who are only infected with HCV do not show anti-RNA. In addition, there are 20% of hepatitis C patients who never show anti-HCV. Therefore, the actual infection rate is higher than the detection rate, and negative anti-HCV cannot exclude HCV infection.

　　Because the HCV content in the blood of hepatitis C patients is very low, it is difficult to detect HCV-RNA directly by nucleic acid hybridization. It is necessary to amplify the nucleic acid first and then determine it by using semi-quantitative polymerase chain reaction (HCVcDNA/PCR, abbreviated as cPCR) to determine the HCV-RNA in the liver and serum, which has the advantages of strong specificity, high sensitivity, and rapidity. Positive HCVRNA is direct evidence of HCV infection, a replication indicator, and is infectious. Since HCVRNA appears earlier than anti-HCV, it can be used for early diagnosis and screening of blood donors. Negative HCVRNA indicates that HCV has been cleared, and can also be used as an indicator of prognosis and efficacy.

　　Hepatitis C patients must pay attention to their diet, as there are many dietary taboos for hepatitis C. The specific taboos are as follows:

　　1. Avoid spicy foods. Spicy foods are prone to cause damp-heat in the digestive tract, leading to a disorder of the liver and gallbladder Qi and weakened digestive function. Therefore, it is advisable to avoid eating spicy foods.

　　2. Avoid smoking. Cigarettes contain various toxic substances that can damage liver function, inhibit the regeneration and repair of liver cells, and therefore, hepatitis patients must quit smoking.

　　3. Avoid alcohol consumption. Ninety percent of alcohol is metabolized in the liver. Alcohol can interfere with and damage the normal enzyme system of liver cells, directly harming liver cells and causing liver cell necrosis. Patients with acute or chronic active hepatitis can experience recurrence or changes in their condition even with small amounts of alcohol.

　　4. Avoid processed foods. Eat less canned or bottled beverages and foods. This is because canned and bottled beverages and foods often contain preservatives, which have varying degrees of toxicity to the liver.

　　5. Avoid excessive use of hormones and antibiotics. 'Three parts of the medicine are toxic,' and any medication can damage the liver and kidneys. Hepatitis patients must take medication under the correct guidance of a doctor.

　　6. Avoid taking supplements and dietary supplements: Balance is the basic condition for maintaining good health. If tonics are not taken properly, the function of the internal organs will be out of balance, the balance will be broken, and it will affect health.

　　7. Avoid excessive protein intake: For patients with severe hepatitis, due to the edema of the gastric mucosa, the thickening and shortening of the villi in the small intestine, and the disorder of bile secretion, the function of digestion and absorption is reduced. If too much protein-rich food such as eggs, turtle, lean meat, etc. is eaten, it can cause symptoms such as indigestion and bloating.

　　8. Avoid high copper diet: When liver function is not good, it cannot regulate the balance of copper in the body well, and copper is prone to accumulate in the liver. Studies have shown that the storage of copper in the liver of patients with liver disease is 5 to 10 times higher than that of normal people, and the content of copper in the liver of patients with biliary cirrhosis is 60 to 80 times higher than that of normal people. Medical experts point out that an excessive amount of copper in the liver can lead to necrosis of liver cells, and an excessive amount of copper in the body can cause renal insufficiency. Therefore, patients with liver disease should eat less food containing a lot of copper, such as jellyfish, cuttlefish, shrimp, snails, etc.

　　α-Interferon (α-IFN) has certain efficacy in the treatment of chronic hepatitis C. The rate of serum HCVRNA becoming negative after treatment can reach 50% to 80%, but about half of the HCVRNA will become positive again after stopping the drug, and α-interferon is still effective. At the same time as the HCV replication index becomes negative, liver function improvement and liver lesions improvement can be seen. This suggests that interferon has inhibitory effect on HCV, but cannot completely clear the virus. The recurrence time is mostly within 6 to 12 months after treatment. If ALT remains normal for 12 months after treatment and serum HCVRNA is negative, it may be cured. The reasons for recurrence are

　　Ribavirin is a broad-spectrum antiviral drug, and its efficacy in treating chronic hepatitis C is not as good as interferon. It has no significant effect on the reduction of HCV-RNA in serum and liver.

　　The sustained response rate of interferon (interferon, IFN) treatment for post-transfusion chronic hepatitis C is 25%, which can prevent 30% of acute hepatitis C from developing into chronic disease. To date, IFN is still recognized as the drug for treating hepatitis C virus.

　　Advanced chronic hepatitis C can be treated with liver transplantation. However, the newly transplanted liver often occurs HCV infection, which is caused by the transmission of HCV outside the liver, and acute fulminant hepatitis can also occur.