Monday, June 22, 2020

HIV transmission

The HIV virus is transmitted from person to person through three major transmission routes: blood, sex, and mother-to-child vertical transmission.

The main manifestation of blood transmission is that blood transfusion and intravenous drug users share needles.

Mother-to-child vertical transmission transmits the HIV virus to the fetus for HIV-infected pregnant women.

Sexual transmission is manifested as homosexual and heterosexual unsafe sex. The probability of transmission of homosexual sex is greatest.

1. Sexual contact transmission between same sex

Among male adult AIDS patients, homosexuals account for a large proportion, especially in the United States and some European countries and regions. With the spread of homosexuality, the number of people infected with HIV or AIDS continues to increase. This type of sexual behavior has become the spread of AIDS. The main way. A man infected with HIV has a large amount of HIV in his semen, with a concentration of 107-8/ml semen. In addition, the anatomical structure of the male anus and rectum is different from that of the female vagina. The vagina is a stratified squamous epithelium, and the rectal mucosa is a columnar epithelium. Its resistance is weaker than that of the female vagina, and its elasticity is lower than that of the vagina. Therefore, in the process of anal sex, they are easy to damage the thin and fragile anorectal mucosa surface and form a wound. During ejaculation, the AIDS virus in the semen enters the blood circulation system through the small wounds of the rectum, infecting the body with AIDS. In addition, tissue-compatible antigen unequal cells pass through the damaged rectal mucosa, and the recipient may undergo graft-versus-host reaction or host-transplant reaction. Both of these can lead to severe immunosuppression. Male homosexuals are not single sex partners. They often have frequent sexual contact with many sex partners. Therefore, not only do sexual activists transmit HIV to passive persons through semen, but there are also other persons with passive persons. AIDS virus semen, and the virus is transmitted to sexual activists. This increases the chance of HIV transmission.

2. Sexual contact transmission between the opposite sex

Heterosexual sexual contact between men and women can also spread AIDS, and the main way of transmission between men and women is the transmission of HIV in men's semen to women through sexual intercourse. It was initially believed that women infected with HIV had less risk of transmitting the virus to men through sexual intercourse. Overall, heterosexuals are less dangerous than homosexuals. However, in recent years, it has been found that the number of patients infected through heterosexual contact has increased. For example, in some developing countries, AIDS is mainly transmitted through heterosexual sexual contact. The ratio of male to female is 1:1. Among them, prostitutes and prostitutes play an important role. effect. However, in some countries and regions, prostitution and other ugly phenomena can not be banned, so it can not really solve the problem of heterosexual HIV infection.

3. Blood transmission

In the laboratory, HIV has been isolated from the patient’s blood, saliva, tears, milk, urine, and cerebrospinal fluid, but epidemiological evidence only shows that blood and semen have a spreading effect. The current transmission of AIDS through blood transfusion is an urgent problem in developing countries, especially in some African countries and regions. Almost most African countries are mainly based on non-voluntary blood donation. Most of them are young and middle-aged people, and they are all in the age group of climax of sexual activity, which means that the blood they provide is likely to have the chance of contracting HIV. Transmitting these blood and blood products to other patients may cause AIDS. For example, hemophilia is an inherited hemorrhagic epidemic caused by the lack of VM or IX, which is an indispensable factor in the body. The treatment of hemophilia is mainly the periodic injection of plasma freeze-dried concentrated preparations or cryoprecipitate preparations. Each batch of concentrated preparations comes from the plasma of 2000-5000 different blood donors. As long as any one of the blood donors has HIV, the preparation will be contaminated, and the hemophiliac patients treated will be infected accordingly. In our country, 4 cases of HIV infection were infected because of the import of blood products imported from foreign countries. According to some data, the concentrated coagulation factor VM or IX prepared by the United States once played an important role in the transmission of AIDS. The incidence of AIDS in hemophilia patients receiving coagulation factor treatment in the country is higher than that in Europe. Higher pollution.

4. Contaminated and unsterilized syringes and needles

Syringes and needles contaminated with HIV are important media for spreading AIDS through blood. In Western countries, intravenous drug poisoning is the second largest group of people at risk of AIDS after homosexuals, especially more than half of the female drug addicts in intravenous drug addicts. Many intravenous drug addicts often share a syringe and needle. If there is an HIV carrier, the needle or syringe will be contaminated, which will cause the chance of mutual infection between them. At present, it is generally believed that the pattern of undisinfected public needle transmission of HIV is similar to that of hepatitis B. In some African countries, the use of unsterilized syringes and injection needles is one of the reasons for the high incidence of AIDS in the region.

5. Mother-to-child transmission

Pregnant women with AIDS or carrying HIV can directly transmit the HIV to the fetus through the placenta. In addition, they can also infect newborn babies before, during, (through birth canal at birth) and after delivery (through breastfeeding). According to information, about 73% of the parents of AIDS infants are AIDS patients or high-risk groups of AIDS; all infants infected with HIV are mothers of HIV-positive serological test carriers; while fathers carry the virus, mothers In families without the virus, no AIDS infants have been found so far. This shows that infant HIV infection always comes from the mother rather than the father. In most cases, it is often the father who is first infected and then transmitted to the mother, and then to the baby.

6. Other ways

For example, when organs contaminated with HIV are used for transplantation, HIV is also implanted in the body.

In addition, in the process of artificial insemination, receiving semen infected with HIV also caused the chance of contracting AIDS.

Professionals in contact with AIDS patients (such as medical staff, police, hairdressers, prison guards, and funeral staff) may be infected if they are exposed to HIV when their skin is damaged.

Although the saliva of AIDS patients contains HIV, so far, there has not been a general case of transmission of AIDS through saliva or shared mouth cups. This may be because the saliva contains factors that prevent HIV infection, which can prevent the invasion of HIV. Therefore, kissing may not be the way to spread AIDS.

In July 1988, the Journal of the American Medical Association published a report on the path of AIDS transmission. The report pointed out that there is currently no indication that HIV is transmitted by accidental contact of saliva, tears, urine, tableware, Phytophthora or insects , Indicating that HIV will not be transmitted through daily contact. HIV will not be transmitted through air, drinking water, food, and unconsumed tableware, clothes, bedding, currency, and other items. There is generally no need to worry about being infected by shaking hands, kissing or sharing phones, toilets, tables and chairs with AIDS patients. Tourist pools and public baths are generally not infected with AIDS. Various domestic animals cannot carry HIV, so AIDS cannot be transmitted through animal bites and scratches.

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