Hepatitis A
Introduction
Introduction to hepatitis A Hepatitis A is an acute liver inflammation caused by infection with hepatitis A virus (HAV). It is mainly transmitted through the fecal-oral route. It is common in children and adolescents. It is one of the common intestinal infectious diseases in China. The incidence and infection rate of hepatitis is the highest. Hepatitis A infection is usually caused by acute patients and subclinical infections. The patient is most contagious from the latent stage to the 10th day after the onset. The fecal-oral route is the main route of transmission. Daily contact is the main route of transmission. basic knowledge The proportion of illness: 0.02% - 0.05% Susceptible people: more common in children and adolescents Mode of infection: fecal mouth spread Complications: liver cirrhosis
Cause
Cause of hepatitis A
Age factor (15%):
Hepatitis A is more common in children in the endemic areas after 6 months of age. As the age increases, the susceptibility gradually declines, so hepatitis A is less common in adults. It has been reported that hepatitis A can also be transmitted through blood and vertically (Foreign Medical Dissemination, 1994), and further research is needed.
Environmental factors (70%):
Hepatitis A takes the faecal-oral route as the main route of transmission, and the way of faecal-oral transmission is diverse. Under normal circumstances, contact with daily life is the main mode of transmission of sporadic morbidity, so in collective units such as child care institutions, schools and troops. The incidence of hepatitis A is high.
Susceptibility and immunity (10%):
People who are not injected with hepatitis A vaccine are generally susceptible to HAV, and people who have hepatitis A or have been infected with hepatitis A virus can obtain long-lasting immunity.
Dietary factors (5%):
The spread of water and food, especially aquatic shellfish such as edulis, is the main mode of transmission of hepatitis A outbreaks.
Prevention
Hepatitis A prevention
(1) Management of infectious diseases
The patients were found and isolated in the early stage. The isolation period was 3 weeks from the date of onset. After the patients were isolated, they were terminally disinfected in their living quarters and activities. After the hepatitis A was found in the child care institutions, medical observations were conducted on close contacts. day.
(2) Cut off the route of transmission
Strengthen water source, diet, manure management, especially to manage the feces of patients with hepatitis A, control the epidemic of hepatitis A, disinfect the shared tableware and drinking utensils, implement a meal-sharing system, and develop a good habit of washing hands before and after meals.
(3) Protecting susceptible populations
For those who are susceptible to contact with hepatitis A, vaccination with human gamma globulin or human placental gamma globulin may be used. The dosage is 0.02-0.05 ml/kg, preferably by injection, within 2 weeks after exposure. The fundamental measures to prevent the spread of hepatitis A are extensive vaccination, domestic application of human embryo lung diploid cell culture, continuous passage at low temperature, obtaining HAV H2 and LA-1 attenuated vaccine strains, and developing a live attenuated vaccine. Preliminary application proves that safety can induce specific antibody production, but the yield is limited and the cost is high. The foreign HAV inactivated vaccine has been approved for wide application. Domestic inactivated vaccines and recombinant vaccines have been studied in China, and genetically engineered hepatitis A vaccine has been developed. It is the direction of future development.
1, passive immunization: hepatitis A immunoglobulin.
2. Active immunization: hepatitis A vaccine.
Live attenuated hepatitis A vaccine (this type of vaccine is only used in China).
Hepatitis A inactivated vaccine (this type of vaccine is widely used in countries all over the world and is internationally recognized).
Complication
Hepatitis A complications Complications liver cirrhosis
Hepatitis A has more extrahepatic complications, 9.7% of those with rash, 33% with proteinuria, and 38.6% with joint pain, which may be related to the formation of transient immune complexes in the serum of patients after HAV infection. There are also some patients with hepatic encephalopathy, aplastic anemia, viral myocarditis, Guillain-Barre syndrome, etc. The mortality rate of hepatitis A is 15.2/100,000.
Symptom
Hepatitis A symptoms Common symptoms Large hepatocyte necrosis Total bilirubin high transpeptidase high appetite loss abdominal pain Appetite loss nausea liver qi stagnation chills bradycardia
After the human body is infected with hepatitis A virus, it usually has an incubation period of about 1 month. There is no symptom at this time. After that, there may be fever, fatigue, loss of appetite, nausea, vomiting and yellowing of the skin. Some patients have bloating or Diarrhea, brown urine, light stool color, check the liver for swelling and tenderness or painful signs, liver function tests showed abnormal alanine aminotransferase (ALT), patients with serum hepatitis A antibody positive or titer increased significantly, symptoms The severity of the disease is 1-2 weeks in mild cases and can be several weeks or longer in severe cases.
During the Huangpi period: acute onset, chills, fever, malaise, loss of appetite, oiliness, nausea, vomiting, abdominal pain, liver pain, diarrhea, bird color gradually deepened, to the end of the period, tea, a few cases Fever, headache, upper respiratory symptoms, etc. are the main manifestations. The current period lasts for 1-21 days, with an average of 5-7 days.
Astragalus stage: The symptoms may be improved, the fever is reduced, but the urine color continues to deepen, the sclera, the skin appears yellow staining, reaching a peak in about 2 weeks, there may be stool color lightening, skin itching, bradycardia and other obstruction The performance of jaundice, hepatomegaly to 1-3cm below the ribs, there is a sense of fullness, tenderness and snoring pain, some cases have mild splenomegaly, this period lasts 2-6 weeks.
Recovery period: The jaundice gradually retreats, the symptoms are alleviated and disappeared, the liver and spleen retract, and the liver function gradually returns to normal. The current period lasts from 2 weeks to 4 months, with an average of months.
Examine
Hepatitis A checkup
Laboratory inspection:
Hematuria: Routine peripheral blood white blood cells are generally reduced or in the normal range i, may be accompanied by an increase in the proportion of mild lymphocytes or monocytes, increased urinary urinary biliary tract in the early stage of the disease, increased urinary bilirubin and urinary bilirubin in the jaundice stage . Liver function tests are most useful for serum ALT, AST, and total bilirubin levels. Studies have shown that patients with hepatitis A have an average ALT peak of 1952 IU/L and AST up to 1442 IU/L. Most patients with dominant infection are accompanied by serum. Increase in total bilirubin levels.
Virological indicators:
1. Anti-HAVIgM: It can be measured in serum about 1 week after onset. Its appearance coincided with the abnormality of clinical symptoms and laboratory indicators, and peaked in the second week. It usually lasts for 8 weeks and a small number of patients can reach more than 6 months. However, individual patients were initially negative and were positive after 2-3 weeks. Therefore, clinical suspected hepatitis A, and anti-HAVIgM negative, should be repeated 1-2 times to avoid missed diagnosis. Currently, anti-HAVIgM is a highly specific indicator for early diagnosis of hepatitis A, and has the advantages of simplicity and speed. Anti-IAV IgG is an indicator of previous infections, as it is a protective antibody that protects the body from re-infection and can be used as an epidemiological survey to understand susceptible populations.
2, anti-HAV-IgA detection: IgA type antibody, also known as secretory antibody, mainly in tears, saliva, urine, gastric juice, milk, nasal secretions, IgA in gastric juice can be discharged into the feces, in the type A Anti-HAV-IgA can be measured in the stool extract of hepatitis patients. Can be used as an auxiliary diagnosis of hepatitis A. In addition, the detection of HAV in stool and serum hepatitis A ribonucleic acid (HAVRNA) also have diagnostic value, but require certain equipment and technology, not as a routine inspection item. In short, for patients with suspected hepatitis A with typical symptoms, the transaminase is significantly increased, and further investigation of HAVIgM can clearly diagnose hepatitis A.
Diagnosis
Diagnosis and diagnosis of hepatitis A
diagnosis
The diagnosis of this disease is based on the patient's apparent weakness, anorexia, nausea, vomiting, urinary yellow and other prodromal symptoms, combined with epidemiological data and examination of ALT, anti-HAV, the general situation can be clearly diagnosed. Laboratory tests for abnormal liver function, determination of ALT is helpful for the diagnosis of early hepatitis, alanine aminotransferase (ALT) is abnormal, often >10 times normal, serum bilirubin >17mol / L, urinary bilirubin positive. However, ALT elevation is not specific, single ALT is more than 2 times higher than normal, and other reasons are excluded. The clinical value and other related examinations have diagnostic value.
Differential diagnosis
Identification of acute hepatitis B, C, D, and E virus, in addition to reference epidemiological data, history of blood transfusion and blood transfusion products and clinical features, mainly based on specific serological examination, and other diseases identification points refer to B Hepatitis.
