Pathways of HIV transmission:

• Sexual (homo- and heterosexual) – the risk of infection with the immunodeficiency virus increases with an increase in the number of sexual partners, infections that are transmitted through sex (herpes, syphilis, chlamydia, trichomoniasis and gonorrhea), bacterial vaginosis;
• parenteral (transfusion – blood transfusion, transplacental – through the placenta from mother to child, injection – injection of drugs);
• vertical – from mother to fetus during pregnancy, as well as infection of the child during delivery and breastfeeding;
• transplantation.

The risk of occupational infection of a medical worker in the workplace increases when: a cut or prick with an object with visible traces of blood, deep tissue damage, a cut in a vein or artery of an infected patient, a high level of viral load in the patient.

The risk of developing the disease by any route of transmission is largely determined by the viral load. At the same time, a low level of RNA content of the pathogen in the blood does not exclude the possibility of HIV infection.

HIV infection pathways are inextricably linked to risky sexual behavior due to alcohol and drug use. Alcohol and drugs increase sexual desire and make behavior less self-critical, which encourages individuals to engage in reckless behavior.

Individual (behavioral) risk factors include:

• promiscuous sexual activity;
• engaging in commercial sex;
• injecting drug use;
• Failure to use preventive measures to prevent diseases that are transmitted through sexual contact;
• sexual abuse;
• early onset of sexual activity, etc.

The probability of HIV transmission is increased by the presence of foci of inflammation, damage to the mucosa of the genital organs.

Domestic transmission of the virus has not been proven.

Risk groups:

• Persons engaged in commercial sex work and their clients;
• Health care workers (especially those working in infectious disease units);
• homosexual men;
• incarcerated people;
• Injecting drug users;
• migrants;
• homeless people;
• adolescents registered with juvenile affairs inspectorates.

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The stage of primary manifestations (2) is characterized by the manifestation of the body’s reaction to the active replication of the virus in the form of acute infection clinic and immune reaction (production of specific antibodies). The second stage may be asymptomatic, the only sign of developing HIV infection will be a positive serologic diagnosis for antibodies to the virus.

The clinical manifestations of the second stage run along the lines of acute HIV infection. The onset is acute, occurring in 50-90% of patients three months after infection, often preceding the formation of HIV antibodies. Acute infection without secondary pathologies has a rather diverse course: fever, various polymorphic rashes on the skin and visible mucous membranes, polylymphadenitis, pharyngitis, lienal syndrome, diarrhea may be noted.

In 10-15% of patients acute HIV infection proceeds with the accession of secondary diseases, which is associated with a decrease in immunity. These can be sore throats, pneumonias of various genesis, fungal infections, herpes and others.

Acute HIV infection usually lasts from a few days to a few months, on average 2-3 weeks, after which in the vast majority of cases it progresses to the latent stage.

The latent stage (3) is characterized by a gradual increase in immunodeficiency. The death of immune cells at this stage is compensated by their increased production. At this time, HIV can be diagnosed by serologic reactions (antibodies to HIV are present in the blood). A clinical sign may be an increase in several lymph nodes from different, unrelated groups, excluding inguinal lymph nodes. There are no other pathologic changes in the enlarged lymph nodes (soreness, changes in surrounding tissues). Latent stage can last from 2-3 years, up to 20 and more. On average, it lasts 6-7 years.

The stage of secondary diseases (4) is characterized by the emergence of concomitant (opportunistic) infections of viral, bacterial, fungal, protozoal genesis, malignancies against the background of marked immunodeficiency. Depending on the severity of secondary diseases, 3 periods of course are distinguished.

4A – loss of body weight does not exceed 10%, infectious (bacterial, viral and fungal) lesions of covering tissues (skin and mucous membranes) are noted. Work capacity is reduced.
4B – weight loss of more than 10% of the total body weight, prolonged temperature reaction, prolonged diarrhea without organic cause is possible, pulmonary tuberculosis may be attached, infectious diseases recur and progress, localized Kaposi’s sarcoma, hairy leukoplakia is detected.
4B – general cachexia is noted, secondary infections acquire generalized forms, esophageal and respiratory candidiasis, pneumocystis pneumonia, extrapulmonary tuberculosis, disseminated Kaposi’s sarcoma, neurological disorders are noted.

Substages of secondary diseases undergo phases of progression and remission, which differ depending on the available antiretroviral therapy or its absence. In the terminal stage of HIV infection, the secondary diseases developed in the patient become irreversible, treatment measures lose their effectiveness, and the lethal outcome occurs several months later.

The course of HIV infection is quite diverse, not always have all stages, certain clinical signs may be absent. Depending on the individual clinical course, the duration of the disease can be either a few months or 15-20 years.

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At first, the body compensates for the mass death of immune cells by producing new ones; over time, the compensation becomes insufficient, the number of lymphocytes and macrophages in the blood significantly decreases, the immune system is destroyed, the body becomes defenseless against both exogenous infection and bacteria inhabiting organs and tissues normally (leading to the development of opportunistic infections). In addition, the defense mechanism against reproduction of defective blastocytes – malignant cells – is violated.

Invasion of immune cells by the virus often provokes various autoimmune conditions, in particular characterized by neurological disorders as a result of autoimmune damage to neurocytes, which may develop even earlier than the clinic of immunodeficiency.

Classification

There are 5 stages in the clinical course of HIV infection: incubation, primary manifestations, latent, secondary disease and terminal. The stage of primary manifestations can be asymptomatic, in the form of primary HIV infection, as well as combined with secondary diseases. The fourth stage, depending on the severity, is subdivided into periods: 4A, 4B, 4B. The periods undergo phases of progression and remission, which differ depending on the available antiretroviral therapy or its absence.

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The reservoir and source of HIV infection is a person: an AIDS sufferer and a carrier. No natural reservoirs of HIV-1 have been identified; it is believed that the natural host in nature is wild chimpanzees. HIV-2 is carried by African monkeys. Susceptibility to HIV in other animal species has not been noted. The virus is found in high concentrations in blood, semen, vaginal gland secretion, and menstrual secretions. It can be excreted from women’s milk, saliva, tear secretion and liquor, but these biological fluids pose a lower epidemiologic risk.

The probability of HIV transmission increases in the presence of skin and mucous membrane injuries (trauma, abrasions, cervical erosion, stomatitis, paradontosis, etc.). ) HIV is transmitted by hemocontact and biocontact mechanism naturally (through sexual contacts and vertically: from mother to child) and artificially (mainly realized by hemopercutaneous mechanism of transmission: during transfusions, parenteral injections of substances, traumatic medical procedures).

The risk of HIV infection in a single contact with a carrier is low, while regular sexual contacts with an infected person significantly increase it. Vertical transmission from a sick mother to her child is possible both in the intrauterine period (through defects in the placental barrier) and in labor, when the child comes into contact with the mother’s blood. In rare cases, postnatal transmission with breast milk is recorded. The incidence among children of infected mothers reaches 25-30%.

Parenteral infection occurs through injections with needles contaminated with the blood of HIV-infected persons, hemotransfusion of contaminated blood, non-sterile medical manipulations (piercing, tattoos, medical and dental procedures performed with instruments without proper treatment). HIV is not transmitted by household contact. Human susceptibility to HIV infection is high. The development of AIDS in persons over 35 years of age, as a rule, occurs in a shorter period of time from the moment of infection. In some cases, immunity to HIV is noted, which is associated with specific immunoglobulin A present on the mucous membranes of the genital organs.

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