How Do I Avoid a Hepatitis A Infection?

Hepatitis A virus, referred to as Hepatitis A and Hepatitis A, is caused by the hepatitis A virus (HAV). It is an infectious disease mainly caused by liver inflammation. It is mainly transmitted through the fecal-oral route. Clinically, fatigue and loss of appetite Hepatomegaly and abnormal liver function are the main manifestations, and jaundice in some cases is mainly manifested as acute hepatitis. Asymptomatic infection is common. This disease can occur at any age, but it is mainly children and adolescents. The clinical symptoms of hepatitis A in adults are generally heavier than in children. Winter and spring seasons are often the peak period for the onset of hepatitis A. The course of the disease is self-limiting, non-chronic, and it is extremely rare to cause acute severe hepatitis. With the use of inactivated vaccines worldwide, the epidemic of hepatitis A has been effectively controlled.

Basic Information

Also known as: Hepatitis A; Hepatitis A
English name: viralhepatitistypeA
Visiting department: Department of Infectious Diseases, Gastroenterology
Multiple groups: Children, adolescents

Common causes: Hepatitis A virus
Common symptoms: Fatigue, loss of appetite, hepatomegaly, abnormal liver function
Contagious: Have
way for spreading: Fecal-oral route

Causes of hepatitis A virus

Hepatitis A virus HAV is a member of the Picornaviridae family and is a genus of hepadnaviruses. After HAV enters the body through the mouth, it enters the bloodstream through the intestine, causing viremia. It reaches the liver after about a week, and then is discharged into the intestine through bile and appears in feces. Detox can be maintained for 1-2 weeks. The main organs affected by the virus are the liver, and the pharynx and tonsils may be sites of extrahepatic reproduction of HAV. The mechanism of HAV-induced liver cell damage has not yet been clarified. It is generally believed that HAV does not directly cause hepatocyte lesions, and liver damage is caused by the immunopathological response of HAV-infected liver cells.

Source of infection

Hepatitis A patients and asymptomatic infections are the source of infection. Hepatitis A patients only excrete pathogens from feces. HAV in the blood mainly occurs 14-21 days before the occurrence of jaundice. During this period, the blood of the patients was infectious. It is transmitted through blood transfusion, but patients' blood is usually non-infectious after jaundice. Patients had the most HAV excretion from feces 2 weeks before the onset and 1 week after the onset, at which time the infection was strongest. However, a small number of patients excreted HAV from feces 30 days after the onset of illness.

2. Ways of transmission

Hepatitis A uses the fecal-oral route as the main transmission route. There are various ways of fecal-oral transmission. In general, contact and transmission in daily life is the main transmission mode of sporadic disease. The incidence of hepatitis A is high. The spread of water and food, especially aquatic shellfish such as cockroach, is the main mode of transmission of hepatitis A outbreaks.

3. Susceptibility and immunity

People who have not received the hepatitis A vaccine are generally susceptible to HAV, and people who have been infected with hepatitis A or have been infected with the hepatitis A virus can obtain lasting immunity.

Clinical manifestations of hepatitis A virus

At the beginning of Hepatitis A, the patient will appear fatigued, unconscious of diet, darkened urine, and sometimes accompanied by fever and other symptoms. In severe cases, the sclera and skin become yellow. Clinically, there are two types of dominant infections and recessive infections without clinical symptoms. Adult infections are mostly manifested as infections, while children or the elderly are susceptible to recessive infections.

Acute jaundice

(1) Incubation period The incubation period for hepatitis A is 15 to 45 days, which lasts an average of 30 days. Patients often have no symptoms during this period, but at the end of the incubation period, about 25 days after infection, a large amount of HAV is excreted in the stool, and the infectious period is the most infectious.

(2) The onset of premature jaundice was acute, and patients with acute chills had fever and chills, and their body temperature was between 38 and 39 ° C. The average heat course is 3 days, and a few days are up to 5 days. He has general weakness, loss of appetite, oiliness, nausea, vomiting, feeling of fullness in the upper abdomen, or mild diarrhea. The upper symptom of upper respiratory tract infection in a few patients is the main manifestation, the urine color gradually deepens and becomes dark brown. This period lasts 5 to 7 days.

(3) During the jaundice period, the consciousness of the palate improves, and jaundice appears after thermal regression. It can be seen that the sclera and skin have different degrees of yellow staining, liver pain, liver enlargement, tenderness and palpitations, and some patients have splenomegaly. This period may have short-term stool coloration, skin itching. Liver function was significantly abnormal. For 2 to 6 weeks.

(4) The icterus jaundice gradually subsided during the recovery period , symptoms improved and disappeared, liver and spleen retracted to normal, liver function gradually returned to normal, and IgG-mediated immune system was established. This period lasts from 2 weeks to April, with an average of 1 month.

2. Acute non-jaundice type

Rare than jaundice. Onset is relatively slow and clinical symptoms are mild, showing only weakness, loss of appetite, pain in the liver area, and abdominal distension. Signs are mostly hepatomegaly, mild tenderness and tenderness, and splenomegaly are rare. Transaminase is elevated. It usually recovers in March.

3. Cholestasis

Capillary bile duct hepatitis was formerly known, and it has been proven that its primary lesions are in the bile ducts of hepatocytes but not in the bile ducts, so the original name of the disease is no longer used. It is mainly caused by acute hepatitis A lysis of liver cells leading to decreased bile secretion, increased bilirubin levels in the blood and increased bile acid concentration, causing jaundice and pruritus of the whole body. Onset is similar to acute jaundice hepatitis, but the symptoms of the digestive tract are mild. The course of the disease is long and jaundice lasts for 2 to 4 months.

This type is a special manifestation of jaundice. The clinical features are lighter gastrointestinal symptoms, longer fever, and long-lasting obstructive jaundice in the liver (several weeks to months). It may have abdominal distension, itching of the skin, Sexual stools become lighter in color, dark in urine and dark brown in color, hepatomegaly, and tenderness. Need to be distinguished from other intrahepatic and external obstructive jaundice.

4. Subclinical

Some patients have no obvious clinical symptoms, but the liver function is slightly abnormal.

5. Severe hepatitis

Rarely. The older the adult infected with HAV, the higher the incidence of severe hepatitis.

6. Stormy hepatitis A

This type accounts for 0.1% to 0.8% of all cases, but the case fatality rate is very high, reaching 50%. This type of onset is very acute, and may have obvious symptoms of gastrointestinal and systemic poisoning such as fever, loss of appetite, nausea, frequent vomiting, and extreme fatigue; jaundice gradually deepens, the liver progressively shrinks, there is a tendency for bleeding, toxic tympanic bowel, liver Smell, peritoneal effusion, acute renal failure and hepatic encephalopathy to varying degrees, until deep coma and convulsions appear. Most patients died of cerebral edema, cerebral hernia, gastrointestinal bleeding, liver and kidney failure, and the course of disease did not exceed 3 weeks.

Hepatitis A virus examination

Laboratory inspection

Routine hematuria: Routine white blood cell counts in the peripheral blood are generally reduced or in the normal range, which may be accompanied by a slight increase in the proportion of lymphocytes or monocytes, increased urobilinogen in the early stages of the disease, and increased urinary bilirubin and urobilinogen during jaundice . Liver function tests are most useful for detecting serum ALT, AST, and total bilirubin levels. Studies have shown that the average peak ALT of patients with hepatitis A can reach 1952 IU / L and AST can reach 1442 IU / L. Most patients with dominant infection are accompanied by serum Elevated total bilirubin levels.

2. Hepatitis A Virology Index

(1) Anti-HAV IgM can be detected in serum about 1 week after the onset of disease. It appeared at the same time as the clinical symptoms and abnormal laboratory indicators, and peaked at the second week. It usually lasts 8 weeks, and a few patients can reach more than 6 months. However, individual patients were negative at the beginning of the disease, and positive after 2-3 weeks. Therefore, clinical diagnosis of hepatitis A and anti-HAV IgM 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 infection. Because it is a protective antibody, it can protect the human body from re-infection, so it can be used as an epidemiological investigation to understand the susceptible population.

(2) Anti-HAV-IgA IgA antibodies, also known as secretory antibodies, are mainly present in tears, saliva, urine, gastric juice, milk, nasal secretions, and IgA in gastric juice can be excreted into feces. Anti-HAV-IgA can be measured in stool extracts. Can be used as an auxiliary diagnosis of hepatitis A. In addition, the detection of HAV in feces and serum hepatitis A ribonucleic acid (HAVRNA) are also of diagnostic value, but require certain equipment and technology and are not used as routine inspection items. In short, in patients with suspicious hepatitis A with typical symptoms, transaminase is significantly increased, and further detection of HAVIgM can confirm the diagnosis of hepatitis A.

Diagnosis of viral hepatitis A

Abnormal liver function based on epidemiological history, clinical manifestations, and laboratory tests is helpful in the diagnosis of hepatitis A. The diagnosis of hepatitis A should be based on virological indicators.

Differential diagnosis of hepatitis A virus

1. Other types of viral hepatitis

The clinical manifestations of acute hepatitis can occur in hepatitis B, C, D, E, hepatitis EBV, and CMV hepatitis. The differential diagnosis is mainly based on specific serological tests, especially hepatitis E and hepatitis A. Similarly, more specific serological tests are needed for identification.

2. Toxic hepatitis

Various systemic infections may cause liver enlargement, jaundice, and abnormal liver function. However, there are clinical manifestations and laboratory evidence of the primary disease, and they recover with the recovery of the primary disease. Serum anti-HAV and IgM negative characteristics can be identified.

Viral Hepatitis A Treatment

Hepatitis A is a self-limiting disease. The treatment is mainly general and supportive treatment, supplemented with appropriate drugs to avoid alcohol, fatigue and the use of liver damage drugs. Emphasis on early bed rest, until symptoms significantly subsided, can gradually increase activities, the principle of not feeling tired.

Acute jaundice hepatitis should be hospitalized for isolation and treatment. The isolation period (3 weeks after onset) is full, clinical symptoms disappear, serum total bilirubin is below 17.1umol / L, and ALT can be discharged when the ALT is less than 2 times normal, but after discharge They should still take a break from January to March, and they should be reviewed regularly for half a year to one year after resuming work.

Prognosis of hepatitis A virus

Hepatitis A is mainly acute hepatitis, without chronicity, and has a good prognosis. When concomitant or overlapping infection with other hepadnaviruses, the condition can worsen or even severe hepatitis can occur. Severe hepatitis accounts for 0.2% to 0.4% of all hepatitis A cases, with a high mortality rate. People who have had hepatitis A or a recessive infection can get lasting immunity.

Prevention of viral hepatitis A

1. Develop good hygienic habits and keep the disease from the mouth. Foods need to be heated at high temperature. Generally, heating to 100 ° C for one minute can make hepatitis A virus inactive.

2. For some foods that easily carry pathogenic bacteria such as snail shells, shells, crabs, and especially sea and aquatic products that can be enriched with hepatitis A virus, they must be cooked and steamed thoroughly to prevent raw, semi-raw and Improper eating habits such as eating directly after pickling.

3. Hepatitis A vaccine can improve the immunity of the population and prevent the occurrence and outbreak of hepatitis A.

4. For close contacts, including all exposed persons whose source of infection is clear (such as food or water), members of schools, hospitals, homes or other units that have been infected with hepatitis A can be given timely injections of gamma globulin. The earlier the injection time, the better. It should not exceed 7-10 days after exposure to infection, and the immune effect can be maintained for 35 days. Close contacts should be medically observed for 45 days.

5. Food-borne infections should be checked for anti-HAV-IgM by the chef and should be isolated for treatment after diagnosis.

6. It is found that patients with hepatitis A should promptly report to the local CDC to take effective measures to isolate the source of infection, cut off the transmission route, protect the susceptible population, and control the spread of infectious diseases. Early reporting is very important for controlling the epidemic.