In recent years, the epidemic of AIDS in my country has shown new characteristics. More than 90% of AIDS cases are sexually transmitted, and it has shown a rapid upward trend. Authoritative data shows that from January to October 2015, there were 97,000 new HIV infection cases in my country, of which 14,200 were adolescents aged 15-24. AIDS has quietly entered university campuses, and newly discovered cases of infection among young students have increased within five years. tripled.

How does AIDS occur

The lipoprotein envelope of the outer layer of HIV is embedded with two glycoproteins, gp120 and gp41. gp120 has affinity with the CD4 glycoprotein on the surface of lymphocytes and can specifically bind to it; gp41 mediates the binding of the virus envelope to Host cell membrane fusion. Therefore, after HIV reaches the blood through damaged skin and mucous membranes or other routes such as blood, it can selectively invade CD4+ lymphocytes.

After HIV invades CD4+ lymphocytes, it synthesizes DNA under the action of viral reverse transcriptase and integrates it into the chromosome of the host cell. The integrated viral DNA can replicate in the cell, form a complete virion, and be released outside the cell. The cell dies. , infect new cells, and can also be in a latent infection state, entering daughter cells as cells divide.

In the early stage of infection, HIV replicates in large quantities, resulting in viremia, and the expression of capsid antigen p24 may appear. The clinical manifestations are symptoms of acute HIV infection. Due to the massive intracellular replication of HIV, CD4+ lymphocytes are damaged and die, and CD4+ T cells are significantly reduced. However, under the immune action of the body, CD8+CTL are activated, killing HIV-infected cells and producing anti-HIV antibodies. The viremia is quickly eliminated and the number of CD4+ lymphocytes rebounds.

How many ways does AIDS spread?

HIV exists in the blood, semen, vaginal secretions, tears, urine, breast milk, and cerebrospinal fluid of infected people. AIDS patients and HIV carriers are all contagious. It is mainly transmitted through sexual contact, followed by blood transmission, such as drug users, recipients, etc. HIV-infected blood or blood products, contact with blood and mucus of HIV-infected persons, etc.

1. Sexual transmission: HIV can be transmitted through sexual intercourse. Sexually transmitted diseases (such as syphilis, gonorrhea, genital warts) or ulcers on the genitals increase the risk of viral infection. There is a large amount of virus in the semen or vaginal secretions of HIV-infected people, and the virus can be transmitted through anal or vaginal intercourse. The chance of transmission through oral sex is relatively small. Unless the healthy partner has a wound or rupture in the mouth, HIV may be transmitted through blood or semen.

2. Blood transmission:

(1) Blood transfusion transmission: If there is HIV in the blood, the person who receives the blood transfusion will be infected.

(2) Blood product transmission: Some patients (such as hemophilia patients) need to inject biological products made from certain components extracted from blood.

(3) Others: dental surgeries, fights, sharing toothbrushes and razors, and bleeding-prone industries such as metal cutting, etc., are actually easy to transmit AIDS through blood.

3. Transmission by sharing needles: HIV can be transmitted from one person to another by using unclean needles, such as intravenous drug users sharing needles; reusing needles and intravenous needles in hospitals.

4. Mother-to-child transmission: If a mother is infected with HIV, she is very likely to infect her child during pregnancy, delivery or through breastfeeding. However, if the mother takes anti-AIDS drugs during pregnancy, the risk of the baby being infected with HIV will be much reduced, and the baby may even be completely healthy.

Can HIV be transmitted through kissing?

Can saliva spread HIV? Generally speaking, HIV is not transmitted through kissing. HIV exists in the blood, semen, vaginal secretions, tears, urine, breast milk, and cerebrospinal fluid of infected people. The content in saliva is very small and will not cause human infection. Someone has calculated that under normal circumstances (without heavy bleeding in the mouth), if the HIV virus contained in saliva alone is to be infected with AIDS, two gallons (7.5 liters) of saliva need to enter the other person's body. Moreover, so far, the scientific community has not found any cases of infection simply through kissing.

However, it should be noted that the HIV virus content in saliva refers to people with no oral health problems. If there is gum disease that causes gum bleeding or oral ulcers, the risk of HIV transmission through kissing will increase to varying degrees.