Introduction to AIDS

AIDS is the Chinese name of English "AIDS", and AIDS is the English abbreviation of acquired immunodeficiency syndrome. It is a fatal infectious disease caused by human immunodeficiency virus (HIV). Aids virus mainly destroys the immune system of human body, making the body gradually lose its defense ability and unable to resist various external pathogens, so it is easy to infect infectious diseases and tumors that ordinary healthy people are not easy to suffer, and eventually lead to death. A person infected with HIV may feel good about himself for a long time, but they can spread the virus to others. It has been less than 20 years since the discovery of AIDS, but AIDS, which is quoted all over the world, is an acquired immunodeficiency syndrome (AIDS), which is caused by human immunodeficiency virus (HIV) and based on severe immunodeficiency. Pneumocystis carinii pneumonia, Kaposi sarcoma, chronic lymphadenopathy, non-Hodgkin lymphoma and various opportunistic infections are the main clinical manifestations of sexually transmitted diseases.

AIDS is a new disease in the last 80 years. In June and July of 198 1, 26 cases of multiple hemorrhagic sarcoma (Kaposi's sarcoma) and 15 cases of pneumocystis carinii pneumonia were reported in the weekly report of morbidity and mortality of CDC. Later, the CDC received 70 cases of these two cases. In the above-mentioned cases, all the patients whose immune function has been tested have significant inhibitory effects on the proliferation induced by T lymphocytes, mitogen and various antigens, so that the significant inhibitory effect of cells has significant inhibitory effects on the proliferation induced by mitogen and various antigens, thus laying a foundation for understanding AIDS as an independent disease. 1982, the disease was officially named as acquired immunodeficiency syndrome (AIDS).

From June 198 1, the United States began to monitor the disease, and by February 1983 (that is, five years after the first patient was found), the CDC had received 1000 AIDS cases. By April of 1986, the number of patients reached 16548, which is only a formal statistic. It is speculated that the actual number of AIDS patients at that time had exceeded 500 thousand. The World Health Organization predicts that by the end of 199 1, the cumulative number of AIDS patients in the world will exceed 1 billion, and 50 million to 1 billion people will be infected with HIV. The organization also predicts that the number of people infected with HIV in the 1990s is 2-3 times that in the 1980s, and there will be 5 million new AIDS cases and hundreds of millions of AIDS-infected people.

At present, AIDS patients are all over the world, among which the United States, Uganda and Brazil rank among the top three. Today, Asia is still the continent with the lowest incidence of AIDS. However, the situation is not optimistic. Thailand, which is famous for its tourism, found 562 1 drug carriers in mid-April, 1989. By August of the same year, the number of drug carriers had exceeded 8,000. It is predicted that by 196, the number of drug carriers will reach 654380+00. 65438-0985 China found the first case of AIDS. 1987 Fujian 1 AIDS patients died shortly after diagnosis. By the end of 1989, China (except Taiwan Province Province) had reported a total of 194 cases of HIV infection, and the epidemic situation involved 10 provinces, municipalities and autonomous regions, which shows that AIDS has indeed been introduced into China.

So far, there is no obvious treatment to improve immune deficiency, and most patients die within 5 years. According to the statistics of 3000 patients initially found in the United States: 16% patients died 3 months after diagnosis; 23% died in June. 57% died in two years and 8 1% died in three years.

AIDS is called "super cancer", and the epidemic of AIDS is called the fourth infectious disease catastrophe in human history. The prevention and treatment of this disease has attracted great attention all over the world.

Pathogen and epidemiology

& ltP> A pathogen: The research on AIDS pathogens made a breakthrough in 1984 and made progress in recent years. It has been proved that AIDS is caused by a retrovirus called HIV. This virus was isolated from AIDS patients by 1983 to 1984 researchers. 1983, a pathogenic virus, called lymph-associated virus (L * * *), was isolated from AIDS patients by the researchers of Pasteur Institute in France. In 1984, researchers from the American National Cancer Institute also found a pathogenic virus from patients with this disease, which is called human T lymphocyte type III virus (HTLV-III). Later, it was confirmed that L*** and HTLV-III are similar in morphology, and both have retroviruses, which are variants of the same virus. Therefore, the World Health Organization issued a communique on July 25, 1986, and the International Society of Virology renamed L * * */HTLV-III virus as HIV, which is commonly called HIV in China.

HIV is a single-stranded RNA virus (RNA virus) with a capsid around it, which is mainly composed of glycoprotein. There is an envelope outside the capsid, and glycoprotein is also the main component. The diameter of HIV is 100 ~ 120 nm, and it has a typical D virus morphology. HIV is not resistant to high temperature and cannot survive without human body. After heating at 56℃ for 30 minutes, it lost its activity. Common disinfectants, such as 75% alcohol, 2.5% tincture of iodine and sodium hypochlorite solution, can quickly inactivate it. But HIV is cold-tolerant, and can survive for 3 months at -75℃. Ultraviolet rays have a weak killing effect on HIV.

& ltP & gtHIV has obvious characteristics of T lymphocytes, especially T 4 lymphocytes (human helper lymphocytes) and neurophiles, and contains a special reverse transcriptase system, which is still a carcinogenic virus to human beings.

Source of infection; The sources of AIDS infection are AIDS patients, patients with AIDS-related syndrome (ARC) and asymptomatic HIV-infected people. At present, HIV has been isolated from blood, semen, tears, milk, urine and vaginal secretions of these three types of people, and HIV can also be isolated from other body fluids, secretions and excretions. Among them, the content of HIV in semen increased, followed by blood and blood products (especially coagulation factor VII products), and the content of HIV in tears, milk, urine and vaginal secretions was less. At present, epidemiological evidence only proves that blood and semen can spread HIV. Whether many people who have no abnormal performance and can get sick normally are another source of infection is still inconclusive.

The three transmission routes of LHIV are as follows: ① Close contact with infected people; ② Contact with or accept blood and blood products contaminated by HIV; (3) HIV-infected mothers pass it on to their children before delivery, during delivery and within a short time after delivery; (4) contact with unsterilized syringes and needles contaminated by HIV; ⑤ Accepting organs, tissues and semen of HIV-infected people. Other routes of transmission have not been confirmed, such as social contact with HIV-infected people in daily work and school; Spread through water and food; Transmission through air, feces or mouth; The spread of insects, etc. If it can't be completely ruled out, the spread of these channels will be less important.

Susceptible population: Most literatures about AIDS refer to susceptible population as high-risk population, which is more susceptible to HIV infection.

1. Homosexuals and hermaphrodites: Among the susceptible population, homosexuals (mainly gay men) and hermaphrodites are in the first place. According to the statistics of the first batch of 3,000 AIDS patients in the United States, 2 140 men are gay or bisexual, accounting for 7 1.3% of the total number of patients. CDC counted the composition of AIDS cases in the United States as of July 1985. 1 1 132 Among the male patients, 87 16 were gay (including bisexuality), accounting for 78%. The proportion of homosexuals in AIDS patients in Europe is similar to that in the United States.

The reason why homosexuals are easily infected with AIDS is related to the prevalence of anal sex in this group. Because: ① The rectal anal canal is different from the epithelial tissue structure of female vagina, and the single-layer columnar epithelium of rectal mucosa, the multi-layer epithelium of anal canal and the multi-layer squamous epithelium of vagina have poor tolerance and anti-friction ability compared with the multi-layer squamous epithelium of vagina; ② The anatomical structure of anal canal is different from that of vagina. The anal sphincter is much stronger than that of vagina, and the anal canal wall is more stressed during anal intercourse. ③ The elasticity of anorectum is lower than that of vagina. Based on these three reasons, anal canal and rectal epidermis are vulnerable to trauma during anal intercourse, resulting in damage and virus invasion. Gay men widely use all kinds of sexual stimulants, especially nitrite inhalers (isoamyl nitrite is the most dangerous) as sexual stimulants and sphincter relaxants to facilitate anal copulation. Nitrite itself is a recognized mutagen, which may lead to immune deficiency. In addition, the forced expansion of rectal mucosal capillaries can also enhance the spread of viruses contained in semen. Homosexuals have frequent sexual activities and many sexual partners, and often suffer from other types of sexually transmitted diseases (such as chancre of syphilis) and diarrhea diseases, which may also increase the chances of HIV transmission. Homosexuality also exists in our country, and we should pay enough attention to this group.

2. Intravenous drug users: This group is the second most susceptible group. According to the statistics of AIDS patients in the United States from June 65438 to July 0985,/kloc-0.5% of male AIDS patients and 53% of female AIDS patients are intravenous drug users. These people often have intravenous injections; Frequent use of syringes and needles without strict disinfection is easy to be infected with HIV. In China, drug abuse has spread in recent years, and gradually shifted from opium to intravenous heroin and cocaine. HIV infection among intravenous drug users may be a relatively more dangerous route in China.

3. Hemophilia patients: Hemophilia patients are infected with AIDS because in order to treat hemophilia, patients often transfuse blood and blood products (especially freeze-dried concentrated preparations containing factor VIII), which increases the chances of blood infection contaminated by HIV. Each batch of factor VIII freeze-dried concentrated preparation comes from the plasma of 2000 ~ 5000 different blood donors, and the pollution risk can be imagined. At present, China has banned the use of imported blood products, which is undoubtedly very beneficial to prevent the introduction of AIDS.

4. Other susceptible groups: Other susceptible groups include blood transfusions, promiscuous foreign lovers, and children whose parents have AIDS. The reasons why these groups are vulnerable are very clear.

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