The transmission mechanism of HIV/AIDS, its multi-system clinical manifestations, and the diagnostic criteria for pre-AIDS (ARC).

128. Clinical Manifestations and Transmission Routes of AIDS AIDS, scientifically known as Acquired Immunodeficiency Syndrome, is an infectious disease caused by human immunodeficiency virus (HIV). (1) Clinical Manifestations: AIDS itself has no specific symptoms. When HIV enters the human body, it destroys the function of the immune system, causing the body to lose its ability to resist various pathogenic factors. If the pathogenic factors only invade a certain system, its clinical manifestations are similar to other diseases of that system, such as fever, sweating, weight loss, diarrhea, cough, and swollen lymph nodes. If HIV invades various systems of the body, it can eventually cause the body to collapse and lead to death. (2) Transmission Routes: HIV exists in the blood, semen, vaginal secretions, and other bodily fluids of AIDS patients or virus-infected individuals. It can be transmitted through the following three routes: ① Sexual contact transmission. During sexual activity, the virus present in semen or vaginal secretions can enter the human body through breaks in the skin and mucous membranes, causing infection, including transmission from male to female, female to male, and male homosexuals. ② Blood transmission. HIV is present in the blood. Intravenous drug use with contaminated syringes, receiving contaminated blood or blood products can lead to HIV infection. Organ transplants from HIV-positive individuals and the use of unsterilized instruments can also cause contamination. ③ Mother-to-child transmission. Also known as perinatal transmission, if the mother is HIV-positive, there is a 30%–50% chance that her infant will be HIV-positive during pregnancy, childbirth, and for a period after delivery.

Diagnostic criteria for AIDS: (1) Medical history: extramarital sexual behavior, intravenous drug addiction, blood transfusion and blood products, or the mother is an HIV-infected person or an AIDS patient. (2) HIV-infected person: no clinical symptoms or only chronic lymphadenopathy syndrome. The tested serum is positive by initial screening tests, such as enzyme-linked immunosorbent assay, gelatin particle agglutination test or indirect immunofluorescence test, and confirmed by confirmatory tests, such as Western blot. (3) AIDS-related syndrome: Patients with certain systemic symptoms and signs of AIDS, but who have not yet shown opportunistic infections or tumors (such as Kaposi's sarcoma or central nervous system lymphoma), are called AIDS-related syndrome (ARC). This disease is between chronic lymphadenopathy and AIDS with rare cancers and serious infections. It is estimated that 25% of patients with AIDS-related syndrome will develop AIDS. Currently, it is believed that both AIDS-related syndrome and chronic lymphadenopathy are pre-AIDS. Regarding the diagnostic criteria for AIDS-related syndromes, the AIDS Task Force of the National Institutes of Health (NIH) and the Centers for Disease Control and Prevention (CDC) jointly stipulate that an individual with two or more of the following symptoms (or signs) and two or more abnormal laboratory values ​​can be diagnosed with AIDS-related syndromes: ● Clinical symptoms (or signs): Unexplained chronic conditions of the following for more than 3 months: ① Lymphadenopathy in ≥2 non-groin areas. ② Weight loss ≥7 kg (15 lbs) or ≥10% of normal body weight. ③ Fever ≥38°C, intermittent or continuous fever. ④ Diarrhea. ⑤ Fatigue (malaise). ⑥ Night sweats. ● Laboratory tests: ① Decreased helper T lymphocytes. ② Decreased ratio of helper T lymphocytes to suppressor T lymphocytes. ③ Anemia or leukopenia or thrombocytopenia/lymphopenia. ④ Elevated serum globulin levels. ⑤ Decreased lymphocyte blast transformation response to mitogens. ⑥ Unresponsive skin to multiple skin antigens. ⑦ Elevated levels of circulating immune complexes. (4) Confirmed Cases ① A person who is positive for HIV antibodies and has any of the following characteristics can be diagnosed as an AIDS patient: ● Weight loss of more than 10% in the past 3-6 months and persistent fever of 38°C for more than 1 month. ● Weight loss of more than 10% in the past 3-6 months and persistent diarrhea (3-5 times per day) for more than 1 month. ● Pneumocystis carinii pneumonia (PCP). ● Kaposi's sarcoma (KS). ● Obvious fungal infection, such as oral thrush or other opportunistic pathogens. ② If the antibody is positive or the symptoms of weight loss, fever, and diarrhea are close to the criteria in the first category above and have any of the following characteristics, a person can be diagnosed as an AIDS patient: ● Helper/inhibitor (CD4/CD8) lymphocyte count ratio <1, decreased CD4 cell count. ● Generalized lymphadenopathy. ● Obvious symptoms and signs of central nervous system space-occupying lesions, including dementia, loss of discrimination, or motor nerve dysfunction.

HIV infection is the only way to contract AIDS, through the exchange of bodily fluids caused by certain risky behaviors. If these risky behaviors can be avoided, the chances of contracting AIDS are extremely low. It's important to correct some misconceptions: people do not contract AIDS through everyday contact, such as mosquito bites or sharing toilets, bathtubs, or telephones. They do not even contract the disease through frequent contact with an HIV-infected family member, including sharing utensils. So, how do people contract AIDS? Most commonly, through blood transfusions or the use of HIV-infected blood products. Fetal infection occurs when the mother is already infected with HIV, and the virus is directly transmitted to the fetus through the shared bloodstream. Another, more common, route of transmission is through risky sexual behavior. Once HIV enters the body, it gradually destroys the immune system. Initially, disease-fighting white blood cells can fight back, producing antibodies to resist the virus (this is what is found in the blood when an HIV test is positive). However, once the virus invades cells, the antibodies lose their ability to attack it. HIV-infected cells then accumulate in large numbers in the lymph nodes, which become factories for replicating and producing new generations of the virus. People who test positive for HIV can remain healthy for many years because the virus persists within the cell membrane and lies dormant there until, about 10 years after the initial infection, it suddenly erupts from the lymph nodes and resumes its attack on the body's immune system. Ultimately, the virus weakens the immune system, causing the patient to die from any disease they may contract, such as pneumonia, tuberculosis, or even Kaposi's sarcoma-a rare cancer.