Hepatitis B virus (HBV) infection is the most important source of infection of hepatitis B virus (ACS) in China, the spread of infection var
Hepatitis B virus (HBV) infection is the most important source of infection of hepatitis B virus (ACS) in China, the spread of infection varies with occupation and living conditions. Chronic asymptomatic hepatitis B virus surface antigen carriers are large, widely distributed, activities such as ordinary people, long time to carry the virus, hepatitis B virus transmission in China is the most important source of infection.
1 blood and iatrogenic transmission
In our country, the transmission routes of HBV infection mainly include: mother to child transmission, daily life contact, blood and sexual contact transmission, some of which are overlapping, may actually be related to blood exposure.
(1) the spread of blood: blood transfusion, blood products, freeze-dried plasma, blood sucking insects (some scholars suspect that hepatitis B virus can be transmitted by mosquitoes, bedbugs and other blood sucking insects, but there is no real epidemiological evidence. Mosquito infectious blood test feeding, within 48 hours of hepatitis B virus in the blood to be digested, short intervals, not media. Hepatitis B virus was retained for 30 days after a single time, and the feces contained virus. The investigation in Africa, that children can bug bloodsucking or insect feces pollution and scratches spread).
(2) drug addiction: intravenous drug users are at high risk for a variety of blood borne viral infections.
(3) iatrogenic transmission: Department of Stomatology (according to the Central People's broadcasting station reported in March 24, 2004 that a National Bureau checks some of the dental hospitals after disinfection with the drill bit, anti-O-positive accounted for 3%), obstetrics and Gynecology, hemodialysis, surgery, Department of dermatology. With the risk of disposal in endoscopy, injection (acupuncture), blood transfusion, blood products, kidney dialysis spread, and the minimum operation.
2 mother to child transmission
(1) vertical transmission: vertical transmission in strict sense, including propagation and intrauterine transmission. It has been confirmed that, duck hepatitis virus can infect ducklings by eggs, fertilized eggs by people can spread, and the most important is the perinatal transmission.
Incidence of intrauterine transmission. The estimated rate of intrauterine transmission was 5% - 10%, but it may be much higher. We detected more than 60% of the fetal liver by molecular hybridization. The past was used to investigate the ELA detection showed that hepatitis B virus e antigen (HBeAg) negative mothers rarely cause perinatal transmission by PCR found that intrauterine transmission of hepatitis B virus e antigen negative mothers can be as high as 40%, and hepatitis B virus surface antigen (HBsAg) in pregnant women with negative or DNA positive hepatitis B virus can occurrence of maternal infant transmission.
The latent infection. HBeAg negative mothers intrauterine infection, birth most of the hepatitis B virus surface antigen negative hepatitis B virus serum DNA detection rate is not high, but in the complete programme of immunization of hepatitis B vaccine, hepatitis B virus surface antibody (anti HBs) no response, suggesting that there may be hepatitis B virus (HBV) infection. It was found that HBV-DNA was detected in peripheral blood mononuclear cells (PBMC), and HBV-DNA was detected in amniotic fluid at birth. The mother's hepatitis B virus is captured and hidden by the placenta by fetal macrophages, which may be a clue to HBV infection. Hepatitis B virus e antigen negative maternal serum HBsAg level is very low, and may not enter intrauterine fetal exposure, and no neonatal immune tolerance lasting for hepatitis B virus surface antigen, delayed response to hepatitis B vaccine can. In the past, due to the majority of neonatal response to the vaccine, may therefore underestimate the incidence of intrauterine infection.
Slow HBV replication in the embryonic cells, and maternal hepatitis B virus core antibody (anti -HBc) inhibition of serum hepatitis B virus core antibody levels decreased gradually after birth, hepatitis B virus infection only gradually, hepatitis B virus core antibody can inhibit the virus, which has been proved by gorilla experiment. Hepatitis B virus transmission rate was higher in patients with lower serum levels of maternal hepatitis B virus core antibody.
Outcome of infection. The mother carrying a different state of occurrence of neonatal infection after different results, hepatitis B virus e antigen (HBeAg) positive mothers neonates often carriers of hepatitis B virus; hepatitis B virus e antibody positive mother communication is often low amount of wild strain infection, often happened in the rare occurrence of hepatitis B virus carrying. Virus carriers; e antibody positive mothers some transmission of hepatitis B virus C or A83 mutation can occur, serious hepatitis, or even fulminant hepatitis.
The transmission mechanism. There are 2 possibilities. One is the placenta during pregnancy may be due to leakage, slight leakage of placenta stripping, maternal blood into the fetal blood; two is the placental infection in a group of hepatitis B virus surface antigen (HBsAg) positive mothers 101 placenta, 40 in situ immunohistochemical detection of hepatitis B virus surface antigen and () or hepatitis B virus core antibody (HBcAg) positive, found from the mother to the fetal surface of the placenta is gradually decreased. It is suggested that hepatitis B virus infection may be involved in cell migration.
(2) perinatal transmission
Incidence rate. Hepatitis B virus surface antigen (HBsAg) was positive in 95% of children infected with hepatitis B virus surface antigen (HBsAg) positive mothers in March. Perinatal infection is the most important form of HBV infection in infants, estimated from the incubation period of hepatitis B virus infection. Hepatitis B virus e antigen (HBeAg) positive mothers of infants will be almost entirely within a year of hepatitis B virus surface antigen positive, the 65%-72% will become the carriers of hepatitis B virus; pregnant women report another 171 cases of hepatitis B virus e antigen positive, 86% children born to hepatitis B virus carriers, the rest the children about 95% hepatitis B virus markers were positive. About 10% of children with hepatitis B virus e antibody positive have a transient infection.
Occurrence mechanism. The mother is infected by blood through a baby's broken skin or placenta. Someone recently observed that the hepatitis B virus surface antigen were detected and neonatal vaginal fluid mother in the gastric juice, closely related to hepatitis B virus surface antigen in gastric juice and hepatitis B virus infection; regardless of antigenemia in babies with the first stage of labor time, cesarean section does not reduce the rate of vertical transmission of hepatitis B virus so, that may be oral intake.
The hepatitis B virus e antigen (HBeAg) positive newborns born to mothers, single inoculation of hepatitis B vaccine still has 15-25% hepatitis B virus infection and hepatitis B immune globulin (HBIG) with 5%-15% of hepatitis B virus infection. The mechanism of vaccine nonresponders may be as follows: one is the mother has a high level of infection, and the ability of active and passive immunization was more than two; the genetic constitution is no response to vaccination; three is immune tolerance in intrauterine infection produced; four from maternal hepatitis B virus e antibody (anti -HBc). Interference; five were hepatitis B vaccine and hepatitis B immune globulin can not prevent the long existence of intrauterine infection.
(3) horizontal propagation
The incidence of hepatitis B virus surface antigen positive rate of less than 1 years old baby is 3-4%, most likely is the vertical transmission; hepatitis B virus surface antigen 1-4 detection rate was 8-12% years old children, growth part from horizontal transmission, 2 times more than the level of infant HBV infection spread vertical transmission.
Occurrence mechanism. The communication between mother and baby extends to the whole preschool, mainly due to living in close contact, the mother of hepatitis B virus surface antigen positive, especially the mother of hepatitis B virus e antigen positive children by level and perinatal transmission of hepatitis B and the common role of virus infection, especially the rate was significantly higher than that of hepatitis B virus surface antigen negative hepatitis B virus surface antigen in children.
In addition, whether breastfeeding had no significant difference on hepatitis B virus infection in infants, breastfeeding on the spread of paradox, an important factor, but in breast milk was detection of hepatitis B virus.
3 daily life, sexual contact transmission
(1) the daily life contact transmission: mainly occurs in the family, but also may occur in the public place, the school or the work unit's collective dormitory, the kindergarten toy transmission frequently, is the active dissemination carrier. Hepatitis B virus surface antigen may be detected in public facilities, even in swimming pool water. According to reports, notes are often highly contaminated, hepatitis B virus surface antigen banknote finger pollution rate can reach 73%.
Many body fluids contain hepatitis B virus or hepatitis B virus surface antigen, blood, semen and saliva more common, can be experimentally transmitted non-human primates. Infectious saliva from the nasal cavity or oral infection can not be infected with the orangutan, it is generally believed that kissing does not spread hepatitis B virus.
Tear, milk, urine, semen, pancreatic juice, bile, cerebrospinal fluid, pleural effusion were detected for hepatitis B virus surface antigen and hepatitis B virus DNA.
Hepatitis B virus or hepatitis B virus surface antigen containing feces, adipose outer mold may be virus particles by biliary secretion of bile is damaged, or there is some damage in the intestinal tract of hepatitis B virus material, it is generally considered impossible by fecal oral transmission.
(2) sexual contact transmission: hepatitis B virus can be transmitted through sexual intercourse. The experimental infection of hepatitis B virus can be successfully established by inoculating infectious semen from the vagina. Hepatitis B virus surface antigen and hepatitis B virus DNA can be detected from semen and vaginal secretions. Hepatitis B virus e antigen positive chronic hepatitis B patients semen, 62% had hepatitis B virus DNA, a group of 57 couples of the party for hepatitis B virus carriers, the other party is susceptible, 27 months after the susceptible markers in serum conversion rate was 52.6%, conversion rate of hepatitis B virus surface antigen positive was 14%, however, China's population has 60% non susceptible.
Hepatitis B is also a sexually transmitted disease. A report from the United States in CDC1993 showed that 50% of patients with acute hepatitis B were due to sexual contact, and the other one was intravenous drug addiction, and the other was found to be a high risk factor. The majority of the patients were investigated by the 31% factors related to the above factors.
In developed countries, sexual contact is the most important route for adult hepatitis B virus infection, and the infection rate is high among male homosexuals. In the survey of prostitutes, HBsAg and HBV infection rates were significantly higher than those in the control group.
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