Tuesday, June 23, 2020

Knowledge of prevention and control of hepatitis A virus

Hepatitis A (Hepatitis A for short) is acute liver inflammation caused by the Hepatitis A virus. It is mainly transmitted through the fecal-oral route and is more common in children and adolescents. It mainly manifests as anorexia, nausea and vomiting, fatigue, liver Hepatic and liver function abnormalities, often have fever at the beginning of the disease, clinically often self-limiting, most patients can return to normal within a few weeks.

1. What are the symptoms of hepatitis A?
(1) Acute jaundice type

1. Early jaundice: The infected patients have an incubation period of 15 to 45 days (30 days on average), most of them are acutely onset, with chills and fever, fatigue, fatigue, muscle aches, lack of appetite, nausea and oiliness, vomiting and upper abdominal discomfort, etc. Lasts a few days to 2 weeks. A few patients have no obvious symptoms. The main signs are tenderness and throbbing in the liver. The total number of peripheral blood leukocytes is normal or slightly lower, lymphocytes are increased, abnormal lymphocytes, urinary bilirubin positive, ALT increased, anti-HAV IgM positive.

2. Jaundice period: about 1 week after the onset of fever, the fever subsides, the urine is like strong tea, the sclera and the skin are yellow, and the jaundice reaches its peak within 1 to 2 weeks. Hepatomegaly, with tenderness and percussion, some patients have mild splenomegaly, ALT increased, and serum bilirubin exceeds 17.1μmol/L for 2 to 6 weeks.

3. Recovery period: Jaundice subsides, symptoms disappear, and liver function returns to normal, lasting from 2 weeks to 4 months, and a few have reached 6 months.

(2) Acute type without jaundice

Generally lighter, shorter course, easy to ignore, only manifested as fatigue, loss of appetite, abdominal distension and liver pain, some patients have no clinical symptoms (subclinical type), may have a large liver. Anti-HAV IgM positive and ALT increased, total bilirubin was below 17.1μmol/L.

(3) Acute cholestasis

The onset is acute, the symptoms of the digestive tract are not obvious, the urine is dark yellow, the sclera and the skin are obviously yellow, and there may be gray stools and itchy skin. Serum bilirubin was significantly increased, mainly direct bilirubin, serum transpeptidase, alkaline phosphatase, cholesterol, etc. were significantly increased, ALT was moderately elevated, jaundice lasted more than 3 weeks, and a few were more than 3 months , And excluding other extrahepatic obstructive jaundice.

(4) Severe hepatitis A

Acute severe onset is urgent and develops rapidly. The course of the disease within 10 days, the jaundice quickly deepens, frequent nausea and vomiting, high abdominal distension, extreme fatigue, bleeding tendency, and rapid neuropsychiatric symptoms. The main signs are disturbance of consciousness, flapping wing tremor, and narrowing of liver dullness. With a total serum bilirubin of more than 171μmol/L, prothrombin time was significantly prolonged, activity was less than 40%, cholinesterase activity, C3, serum cholesterol and cholesterol lipids were significantly reduced. But there are also those who do not have obvious jaundice or no jaundice and have the first symptom. Patients with a disease course of more than 10 days are subacute severe hepatitis, and the clinical manifestations are the same as acute severe. The main complications of severe hepatitis are as follows:

1. Hepatic encephalopathy: common, according to the degree of clinical manifestations, it is divided into grade Ⅳ. Level Ⅰ: Sleep disturbance, mental disorder, behavior disorder, indifferent or excited expression; Level Ⅱ: mental disorder, disorientation, decreased computing power, hypertensive reflex, increased muscle tone, flutter-like tremor and ankle clonus, Pakistan Positive Binsky sign, altered EEG; Grade III: lethargy, responsiveness, orbital response slow, painful presence, increased muscle tone, fluttering tremor, positive pyramidal beam sign, abnormal EEG; Grade Ⅳ: Coma, unresponsiveness, no response to various stimuli, decreased muscle tone, and severe changes in EEG.

2. Cerebral edema: more common, manifested as headache, vomiting, blurred vision, disturbance of consciousness, irritability, increased blood pressure, bulbar conjunctival edema, pupillary changes (smaller, moderately enlarged, suddenly large and small, unequal ) And respiratory changes or even respiratory arrest, often coexist with hepatic encephalopathy.

3. Bleeding: manifested as ecchymosis of the skin and mucous membranes, bleeding from the nasal cavity, oral cavity and gums. Some patients may have hemoptysis, vomiting blood, blood in the stool or urine, or even bleeding from the upper digestive tract.

4. Hepatorenal syndrome: When liver failure occurs, the renal blood flow decreases and the glomerular filtration rate decreases, and the small blood vessels of the kidney are highly spasmodic, manifesting as oliguria or anuria.

2. How to prevent hepatitis A?
(1) Control the source of infection

Acute patients should be isolated according to the digestive tract until 3 weeks after illness. Patients in nurseries must be isolated until the liver function is normal and the pathogenic signs are negative. The feces and excrement of patients should be strictly disinfected, and the food personnel of production and operation should be checked regularly.

(2) Cut off the transmission route

Do a good job in environmental hygiene, strengthen the management of water sources and feces, develop good hygiene habits, and avoid semi-cooked aquatic products.

(3) Protection of vulnerable groups

The gamma globulin preparation contains a more potent anti-HAV, which can be effectively prevented by injection within 7 to 14 days after contact with the patient. In recent years, the hepatitis A vaccine has been widely used, it is safe and immunogenic, and can produce neutralizing antibodies that can prevent and stop infection. China’s Zhejiang, Shanghai, Kunming, Changchun and other places have produced live attenuated hepatitis A vaccines. From the perspective of vaccination of primary school students and some children, the reaction is light and the safety is good. The inactivated vaccines of both Shrek and Merck also have good antigenicity. The genetically engineered vaccine currently under development is an ideal vaccine with high purity and high price for preventing hepatitis A.

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