194. Pathological anatomy of infection caused by hiv.

The causative agent is a virus from the family of T-lymphotropic retroviruses. 4 periods:

1. The duration of the incubation period depends on the path and nature of infection, the amount of the infecting dose, the initial state of the immune system, it lasts from several weeks to 10-15 years. During this period, the fact of infection itself can be established by determining the antigen or anti-HIV antibodies in the blood. The content of the virus antigen in the blood is increased at first, then, starting from the 6th-8th week, when anti-HIV antibodies appear, it decreases, i.e. seroconversion occurs. Some researchers distinguish seroconversion in the independent period of AIDS. Often there are no symptoms during the incubation period, but sometimes a syndrome similar to mononucleosis is noted: fever, an increase in different groups of lymph nodes, sometimes acute encephalitis. The manifestations of this syndrome usually subside within a few weeks.

2. The second period is the period of persistent generalized lymphadenopathy, characterized by persistent, for several months, an increase in different groups of lymph nodes. The basis of lymphadenopathy is non-specific hyperreactivity of B cells, which is manifested by follicular hyperplasia of lymph nodes (an increase in lymphoid follicles and their light centers). The duration of the stage is 3-5 years.

3. The third period of the disease occurs against the background of moderate immunodeficiency of the AIDS, or AIDS-associated complex. It is characterized by fever, lymphadenopathy, diarrhea, and slight weight loss. Against this background, there is a tendency to secondary infections - acute viral respiratory infection, shingles, pyoderma. This period lasts for several years.

4. The fourth period of the disease, which lasts about 2 years, is the period of AIDS. It is characterized by opportunistic infections and tumors, exhaustion and dementia. During this final period, as a rule, the number of antibodies is reduced, they may not be detected at all. The number of viral antigens is increasing, which must be taken into account in the diagnosis of AIDS.

Pathological anatomy. In AIDS, changes in lymph nodes, characteristic UHC lesions, and changes typical of opportunistic infections and tumors are determined. Follicular hyperplasia of the lymph nodes is replaced by complete depletion of their lymphoid tissue (Fig. 24-5). The lymph nodes are reduced, they are difficult to identify. The central nervous system lesion is vicencephalomyelitis, in which the main changes are determined mainly in the white matter and subcortical nodes of the brain. Microscopic examination reveals microglial nodules, multinucleated symplasts, in which HIV particles can be detected. Foci of softening and vacuolization of white matter are visible in the lateral and posterior columns of the spinal cord. Due to the demi-linization, the white substance acquires a grayish tint.