甲型肝炎

　　甲型肝炎，即甲型病毒性肝炎的简称，是由甲型肝炎病毒（HAV）引起的。甲型肝炎病毒（HAV）是小核糖核酸病毒科的一员，为嗜肝RNA病毒属。HAV经口进入体内后，经肠道进入血流，引起病毒血症。约过一周后到达肝脏，随后通过胆汁排入肠道并出现粪便中，粪便排毒能维持1-2周。病毒侵犯的主要器官是肝脏、咽部和扁桃体，可能是HAV肝外繁殖的部位。HAV引起肝细胞损伤的机制尚未明确，一般认为HAV不直接引起肝细胞病变，肝脏损害是HAV感染肝细胞的免疫病理反应所引起的。

　　Hepatitis A has more extragenital complications, with 9.7% of patients having skin rash, 33% having proteinuria, and 38.6% having joint pain, which may be related to the formation of transient immune complexes in the patient's serum after infection with HAV. Some patients may also have hepatic encephalopathy, aplastic anemia, viral myocarditis, Guillain-Barré syndrome, and other complications.

　　After the human body is infected with hepatitis A virus, there is usually a latent period of about 1 month, during which there are no symptoms, and then fever, weakness, decreased appetite, nausea, vomiting, and yellowing of the skin may occur without other causes. Some patients may have abdominal distension or diarrhea, brown urine, pale stool, and signs of liver enlargement, tenderness, or percussion pain, and liver function tests show marked abnormalities in alanine aminotransferase (ALT). The hepatitis A antibody in the patient's serum is positive or the titer is significantly increased, with varying degrees of symptoms, mild cases lasting 1-2 weeks, and severe cases can last for several weeks or longer.
　　1. Pre-jaundice period:The onset is acute, with symptoms such as chills, fever, general weakness, loss of appetite, aversion to oil, nausea, vomiting, abdominal pain, pain in the liver area, and diarrhea. The color of the patient's urine gradually deepens, reaching a tea-like color at the end of this period. A few cases are mainly manifested by fever, headache, upper respiratory symptoms, etc. This period lasts from 1 to 21 days, with an average of 5-7 days.
　　2. Jaundice period:Self-aware symptoms may improve, fever subsides, but urine color continues to deepen, the sclera and skin appear jaundice, reaching a peak within about 2 weeks. Patients may also have pale stool color, skin itching, bradycardia, and other obstructive jaundice symptoms. The liver enlargement reaches 1-3 cm below the rib, with a full feeling, tenderness and percussion pain, and some cases have mild splenomegaly, which lasts for 2-6 weeks.
　　3. Recovery period:Jaundice gradually subsides, symptoms alleviate and disappear, liver and spleen shrink, liver function gradually returns to normal. This period lasts from 2 to 4 months, with an average of 1 month.

　　The following 7 aspects should be noted for the prevention of hepatitis A:
　　1. Develop good hygiene habits and control the 'disease from the mouth' gate. Wash hands before and after meals, do not drink raw water, and eat less or no cold food. When eating fruits, vegetables, and other vegetable foods, they must be cleaned thoroughly. Leftover food should be stored in the refrigerator and heated thoroughly before being eaten again. Especially when processing food, high-temperature heating should be paid attention to, generally, heating to 100℃ for one minute can make the hepatitis A virus lose its activity.
　　2. When eating foods that are prone to carry pathogenic bacteria, such as snails, shellfish, and crabs, especially those that can accumulate hepatitis A virus, such as sea and freshwater products like clam, they must be cooked and steamed thoroughly. Abolish the bad eating habits of eating raw, half-cooked, and directly eating after pickling.
　　3. Pay attention to the elimination of pests such as flies and cockroaches to avoid the transmission of diseases by vectors.
　　4. Do not eat at small restaurants or street vendors without a health permit, where service personnel do not have health certificates, and sanitation facilities are incomplete.
　　5. Vaccination against hepatitis A can improve the immunity of the population and prevent the occurrence and outbreak of hepatitis A.
　　6. People with symptoms such as fever, fatigue, anorexia, nausea, vomiting, and jaundice should go to the hospital's intestinal clinic for an early diagnosis, early reporting, early isolation, and early treatment.
　　7. It is necessary to promptly report hepatitis A patients to the local disease prevention and control center and take effective measures to isolate the source of infection, cut off the route of transmission, protect susceptible populations, and control the spread of infectious diseases. Early reporting is of great significance for controlling the epidemic.
　　

　　The diagnosis of hepatitis A, in addition to relying on symptoms and signs, also requires laboratory examination, which is an indispensable means. Common examination methods are as follows:

　　One. Laboratory examination
　　1. Blood and urine routine tests: The peripheral blood routine white blood cell count is generally reduced or within the normal range, and may be accompanied by a slight increase in the proportion of lymphocytes or monocytes; in the early stage of the disease, the level of urobilinogen in urine increases, and during jaundice, both bilirubin and urobilinogen in urine increase.
　　2. Liver function tests: The detection of serum ALT, AST, and total bilirubin levels is most useful. Studies have shown that the average peak value of ALT in patients with hepatitis A can reach 1952 IU/L, and AST can reach 1442 IU/L. Most apparent infectious cases are accompanied by an increase in serum total bilirubin levels.

　　Two. Virological indicators
　　1. Anti-HAVIgM: It can be detected in serum about one week after onset. Its appearance is consistent with the time of onset of clinical symptoms and abnormal laboratory indicators, reaching a peak in the second week. Generally, it lasts for 8 weeks, and a few patients may last for more than 6 months. However, some patients may initially test negative and show positive results after 2-3 weeks. Therefore, for clinical suspected cases of hepatitis A with negative anti-HAVIgM, 1-2 repeat tests should be performed to avoid missed diagnosis.
　　2. Detection of anti-HAV-IgA: IgA antibodies, also known as secretory antibodies, are mainly present in tears, saliva, urine, gastric juice, breast milk, and nasal secretions. The IgA in gastric juice can be excreted into feces, and anti-HAV-IgA can be detected in the fecal extract of patients with hepatitis A, which can be used as an auxiliary diagnosis for hepatitis A. In addition, the detection of HAV in feces and serum hepatitis A ribonucleic acid (HAVRNA) also has diagnostic value, but it requires certain equipment and technology and is not considered a routine examination item. In summary, for suspected cases of hepatitis A with typical symptoms and significantly elevated transaminases, further examination of anti-HAVIgM can help confirm the diagnosis of hepatitis A.

　　In addition to routine treatment, patients with acute hepatitis A should also pay attention to dietary aspects. The following are specific dietary precautions:

　　First, Suitable Diet
　　1. Improve drinking water hygiene. Strengthen water disinfection, whether it is tap water, well water, river water, or pond water, it should be disinfected.
　　2. The dietary principle is light, easy to digest, and nutritious.

　　Second, Taboo Diet
　　1. Do not eat unclean food and do not drink raw water.
　　2. Shellfish such as scallops and clams may adhere to the hepatitis A virus, and they should not be eaten raw or half-cooked.
　　3. Do not wash direct-oral foods such as pickled vegetables and cold dishes in potentially contaminated water.
　　4. Avoid taking too many drugs.
　　5. Avoid alcohol.
　　6. Avoid greasy, high-fat, and fried foods such as fish roe, egg yolks, pork liver, pork brain, oil cakes, fried dough sticks, roast duck, etc.

　　The treatment principle for acute hepatitis A: Focus on appropriate rest and reasonable nutrition, with selective use of drugs as a supplement; it is advisable to avoid alcohol, prevent overexertion, and avoid using liver-damaging drugs; medication should be simple rather than complicated.
　　1. Early strict bed rest is most important. Gradually increase activity as symptoms improve, with the principle of not feeling tired. Treatment continues until symptoms disappear, isolation period ends, and liver function is normal before discharge. Patients may gradually resume work after 1-3 months of rest.
　　2. Diet should be light, easy to digest, and nutritious. Foods should contain a variety of vitamins, have sufficient calories, and appropriate protein; fat should not be restricted too strictly.
　　3. If there is little food intake or vomiting, use 1000-1500ml of 10% glucose solution with 3g of vitamin C, 400mg of Hepatol, and 8-16U of ordinary insulin for intravenous infusion, once a day, and can also add energy preparations and 10% potassium chloride.
　　4. Follow the doctor's advice to administer intravenous energy and vitamin supplements.