TRANSMISSION
HIV — antropos. Animals in vivo HIV-1 infected, and attempts at experimental infection of monkeys over their quick recovery.
Source HIV — infected persons at any stage of the disease, including the incubation period.
Most likely the transmission of HIV from a person at the end of the incubation period, in the period of initial manifestations in the late stage of infection, when the virus concentration reaches its maximum.
HIV infection refers to dolgorukim diseases. From the moment of infection until death without highly active antiretroviral therapy, it may take from 2-3 to 10-15 years. Naturally, it averages.
The human immunodeficiency virus can be in all biological fluids (blood, semen, vaginal secretions, breast milk, saliva, tears, sweat, etc.), overcomes the transplacental barrier. However, the content of viral particles in biological fluids is different, which determines their different epidemiological significance. The human immunodeficiency virus affects all cells have the CD4+receptor. Tropism for CD4+ T lymphocytes leads to the progression of HIV infection through the development of immunodeficiency. In the body of an infected person HIV is found in different environments and tissues. For example, the lymphoid tissue in the brain and internal organs.
Biological substrates have HIV and have the greatest epidemiological significance in the spread of HIV:
- blood
- sperm and predjuices
- vaginal and cervical secret
- breast milk
The virus may be present in other substrates (but its concentration is small or the substrate is not available, such as the CSF):
- cerebrospinal fluid (CSF)
- urine
- saliva
- lacrimal fluid
- the secret of the sweat glands
Different contents HIV in biological fluids determines their epidemiological significance as forces for implementing the transmission of the pathogen.
Susceptibility to HIV in people universal and is determined by Geno-, phenotypic polymorphism of individuals, which can manifest as complete (or incomplete) restriction of the possibility of HIV infection and in accelerating or reducing the rate of development of clinical symptoms of infection.
During the epidemiological analysis of the global situation in relation to HIV infection it was found that there are certain racial differences in the dynamics of infection and progression of HIV infection, with the dominant role belongs to the antigens of the major histocompatibility complex. It turned out that the most sensitive (susceptible) to HIV were blacks, less — Europeans and the least — Mongoloids.
Currently described three genes (CCR5, CCR2 and SDF1)controlling the synthesis of molecules involved in the penetration of HIV into the host cell, i.e. people with homozygous form of these genes are resistant to HIV infection sexually, and heterozygous is slightly less stable. However, this symptom is not associated with immunity to HIV through blood transfusion and the use of psychoactive substances parenterally.
For the transmission of HIV requires not only the presence of source of infection and susceptible subject, but the creation of appropriate conditions for this transfer. On the one hand, the allocation of HIV from the infected organism in natural situations is in limited ways: with semen, secretions of the genital tract, breast milk, and in pathological conditions of blood and various exudates. On the other hand, for HIV infection with the subsequent development of infection should the pathogen enters in the internal environment of the body.
HIV transmission is performed by the following mechanisms: natural — pin, vertical and artificial (artifactual). The ways of realization of mechanisms of transmission varied: sexual, transplacental, parenteral (injection, transfusion, transplantation). The dominant mechanism of transmission is contact, realized through sexual contact. The leading role of sexual transmission due to high concentration of the virus in semen and vaginal secretions of infected persons.
Believe that the share of sexual transmission accounts for 86% of all cases of infection, of whom 71% — heterosexual and 15% homosexual contacts. The reality of HIV transmission in the direction of male–male, male–female and female–male recognized. At the same time, the ratio of infected men and women are different. At the beginning of the epidemic, the ratio was 5:1, then 3:1.
Vertical HIV transmission is implemented in infected pregnant women (antenatal pathway). Infection of a child can occur during the act of childbirth (intrapartum path), and then postnatal, breastfeeding.
The main route of HIV infection neonatal — perinatal. The proportion of HIV transmission in different periods perinatal period is not precisely defined, but fetal infection in early pregnancy occurs in 30-50% of cases in the absence of prevention of perinatal HIV transmission.
The probability of infection of the child during breastfeeding is around 12-20%. Moreover, the transmission of the virus can occur not only from infected mother to child and from infected children breastfeeding woman in the case that a child born of a healthy woman who was infected with HIV, as described in the epidemiological investigation of nosocomial outbreak in Elista.
HIV is transmitted through transfusion of infected whole blood and made of her products (Packed red cells, platelets, and fresh frozen plasma). Transfusion of blood from HIV seropositive donors, recipients become infected in 90% of cases. Normal human immunoglobulin, albumin are not dangerous, because the technology of producing these drugs and the stages of control of raw materials eliminate the infection of HIV.
Relatively rare, but the possibility of infection is transplantation of organs, tissues and artificial insemination of women.
HIV transmission by airborne droplets, food, water, vector-borne paths are not proven.
"Artificial" (artificial) mechanism triggered by medical manipulation, accompanied by violation of the integrity of skin and mucous membranes, that is, implemented hospital-acquired HIV infection. This mechanism has a variety of ways and factors of transmission, but in HIV infection the role of this mechanism in the spread of HIV is negligible.
An example implementation of artificial mechanism of HIV infection can serve as a nosocomial infection of children with HIV in the cities of Elista, Rostov-on-don, Volgograd.
Currently, the path of HIV infection is not being implemented due to the fact that strict control of blood products and perform all invasive diagnostic interventions in compliance cleaning and sterilization of medical instruments, use of disposable medical instruments (e.g. syringes).
However, injecting ("injecting") the transmission of HIV is quite common among drug addicts who use intravenous psychoactive substances.
The risk of HIV different for different groups of the population, respectively, we can distinguish the contingents of the high risk of infection: homosexual, bisexual, "injecting drug users", recipients of blood and blood products, prostitutes, vagrants, proponents of free love, hotel staff, air-lines of international transport, the soldiers, seamen, immigrants, refugees, seasonal workers, tourists.
The role and importance of these risk factors is ambiguous, often marked by their combined effect, and to isolate the leads from a single set of risk factors operating in the territory at this time, is not possible.