Human immunodeficiency virus (HIV) is a retrovirus that suppresses the human immune system by integrating into the DNA of a human cell and blocking its protective functions.
When HIV enters the bloodstream, it attaches to the blood cells that are responsible for immunity, and the active reproduction of HIV begins. Throughout the period of the disease there is no effective response to the presence of HIV. This can be mainly explained by the fact that immune cells are damaged and cannot function properly. HIV is characterized by the absence of pronounced and characteristic symptoms and it is possible to find out about the presence of HIV infection in the body only after passing an HIV test.
In the external environment, HIV is not stable: at a temperature of 56 ° C it dies in 30 minutes, when boiled - instantly. The virus dies quickly when using disinfectants, under the influence of 20% ethanol, ether, acetone, 0.2% sodium hypochlorite, 1% glutaraldehyde. However, it is resistant to ionizing radiation, ultraviolet radiation. In the blood intended for transfusion, the virus lives for years, and in frozen serum its activity persists for up to 10 years.
Ways of HIV transmission:
Sexual (with homo- and heterosexual contacts). In the majority of cases, HIV is sexually transmitted. This is due to the high concentration of HIV in semen, especially during inflammatory diseases and the presence of sexually transmitted infections (STIs). For this reason, the risk of HIV transmission in the presence of STIs increases. In addition, concomitant infections are often associated with the development of various formations that disrupt the integrity of the genital mucosa - cracks, ulcers, etc. HIV can also be found in vaginal discharge and cervical discharge.
Parenteral (transfusion of blood and its components, as well as injections). Injecting drug users are at increased risk of contracting HIV when using syringes and needles. There is also a high risk during a blood transfusion procedure or its components. If the infected blood was transfused to a healthy person, in 90-100% of cases there is an infection. With the introduction of mandatory HIV testing of blood donors, the risk of infection has been significantly reduced. However, even in developed countries, cases of infection of a whole group of patients from one HIV-infected donor are rare, due to violations of the method of testing donor blood.
Vertical (from mother to child in utero, during childbirth or during breastfeeding). HIV has the ability to cross the placenta, so infection of the fetus can occur during pregnancy or childbirth. The magnitude of the risk depends on the level of medical supervision and treatment of the woman during pregnancy, the mother's medical indications and the stage of HIV. The possibility of infecting a child during childbirth is indicated by the following observations: 1) in multiple pregnancies, the twin born first has a higher risk of infection from an HIV-infected mother than the twin born second; 2) the risk of infection from an HIV-infected mother during a cesarean section is lower than during delivery through the natural birth canal. There is also a real risk of transmitting the infection during breastfeeding. If the mother is HIV-positive, breastfeeding is contraindicated.
How it is impossible to get HIV:
Transmission of HIV infection through household contact, as well as insect bites for more than twenty-five years of HIV study has not been registered. There is also no convincing evidence of HIV transmission through saliva - no significant cases of HIV infection have been reported during kissing or accidental saliva on the skin and mucous membranes. There are at least two reasons that explain the low probability of HIV infection through saliva: 1) the virus is found in the saliva of only a few HIV-infected people and is present there in small quantities; 2) saliva contains a protein, a secretory inhibitor of leukocyte proteases, which prevents infection of HIV cells. Although there are cases of HIV infection after contact with saliva, in reality they may be due to the transmission of the virus through the blood. Although HIV can be present in almost all body fluids, there is no evidence that the virus is transmitted through tears, sweat, or urine. The hypothesis of HIV infection involving insects has also not been confirmed.
What protects against infection ?:
- the presence of a permanent sexual partner;
- avoid casual sex (with any casual sex, use a condom). This will protect not only from HIV, but also from sexually transmitted infections, hepatitis B and C;
- use of individual syringes, needles.