What is AIDS ? Details of Distribution, Agent, Host, Mode of transmission.

There was a time when the deadly disease known as AIDS was a classic medical crisis. But as hopes for a sure cure or vaccine have faded the disease has turned into an agonizing dilemma for countries around the world. triggering debates about delicate issues of public health and private morality. AIDS Is an epidemic disease caused by HIV (Human Immunodeficiency Virus) and manifested by the development of opportunistic infection, certain tumors and frequent involvement of CNS—clinical conditions at least moderately predictive of a defect in cell-mediated immunity, occurring in a person with no known cause for diminished resistance to that condition.

Details about AIDS

AIDS is a socio-medical problem of great magnitude, and as such, there is a rapidly growing body of literature devoted to AIDS. Here we summarize only the salient epidemiological features before discussing the clinical symptomatically and prevention and control of this new scourge. Distribution of AIDS. There has been a growing openness of countries in responding to pandemic AIDS and the number of countries reporting AIDS cases to WHO increased rapidly. worldwide surveillance of AIDS and HIV infection is coordinated by the WHO Global Program on AIDS (GAP). Table – New infections and adult and child death from HIV/AIDS in 2002.


Region New infection in Adult and child death in 2002
Sub-Saharan Africa 3,500,000 2,400,000
South and southeast Asia 800,000 440,000
East Asia and Pacific 270,000 45,000
Eastern Europe and Central Asia 250000 25000
Latin America 150000 60000
North Africa. Middle East 83000 37,000
Caribbean 60,000 42000
North America 45000 15000
Western Europe 30,000 8000
Australia and New Zealand 500 >100
Total 5.000.000 3,100,000

Source: UNAIDS, World Health Organisation.   UNAIDS. World Health Organization recently revealed that well above 42 million people are now living with the disease in the world. As the world enters into the third decade of the AIDS epidemic, southern Africa remains at the epicenter of the disaster. Table 13.35 shows the worldwide distribution of new HIV infections in one year (2002). Of the 5 million new cases of HIV infection, 800.000 were children under 15 years. AIDS deaths in 2002 were 3.1 million.

Agent of AIDS

The AIDS is caused by a virus known previously as lympha.deriopathy-associated virus human T-lymphotropic virus type III (HTLV­III). and now universally called the human immunodeficiency virus (HIV). HIV belongs to the family of human retroviruses and the viruses are cytopathic, CD4+T cells being their important target. Cytopathic retrovirus HIV includes HIV-I and more recently described HIV-2; both of them are cytolytic for T cells.T cells possess a molecule called CD4 on their surfaces which helps the immune cells to communicate with each other. HIV, on gaining entry into the CD4 cells, manipulates genetic apparatus and inserts its own genetic information, turning the cell into a factory that processes several new copies of itself. The brigade of these newly multiplied HIV escapes. forth the cell by punching holes in the cell’ membrane thereby destroying it. Out in the bloodstream, the viruses can now infect new CD4 cells. Monocytes are relatively refractory to the cytopathic effects of HIV, but the consequences of monocyte and macrophage infection may well be the major. the reservoir of HIV in the body, and secondly, they provide a safe vehicle for HIV to be transported to various parts of the body. Depletion of CD4 + helper-inducer T cells is a key event in the causation of AIDS and their depletion leads to lymphopenia with inversion of the CD4-to-CD8 ratio in the peripheral blood; the normal ratio 2 to 1 may become 0.5 to 1 in patients with AIDS. The most important abnormalities of immune function as a consequence of decreased in vivo T cells are susceptibility to opportunistic infection,: susceptibility to neoplasm and decreased delayed: type of hypersensitivity. The strange thing about Env is the long time it takes to manifest these’ damaging features. After inserting its genetic.: blueprint into that of the host CD4 cell, HIV may lie ‘hidden’ for several years before triggering its rapid multiplication and destruction of the cell. This way it escapes being attacked by antibodies which are circulating in the blood to seek out and destroy it. The dangerous game of hiding and seek ends when so many of the CD4+T cells have been destroyed that the victims are unable to mount an antibody response to a new antigen. HIV is readily inactivated by heat and by disinfectants such as glutaraldehyde.

Please, read to get the facts and list of infectious diseases types, causes, prevention, and treatment, and learn how they spread.



Due to its predominantly sexual mode of transmission, approximately 90% of known cases in developed and developing countries are between 20 and 43 years of age. The epidemiology of AIDS is related to the pattern of transmission; as such the epidemiology of AIDS in Africa is quite different from the pattern seen in the United States, the transmission of HIV being especially through heterosexual contact in Africa. Epidemiologic studies in the United States identified five groups Of people at risk’ for developing AIDS. They are: (1) Homosexual or bisexual males 71.4%; (2) Intravenous drug abusers 18.4%; (3) Heterosexual contacts of members of other high-risk groups 3.9%; (4) Haemophiliacs, especially who received large amounts of factor VIII concentrates 1%; (5) Blood and blood component recipients who are not hemophiliacs, but who received transfusions of whole blood or components 2.5%. Approximately 2.8% of the patients did not belong to any of the high-risk groups mentioned above. and the mode of transmission of these cases remains unidentified. In marked contrast to the above epidemiological features, 90% of the AIDS patients in Africa have no identifiable risk factors. Heterosexual transmission seems to be the dominant mode of transmission in Africa and as such, the male-to-female ratio of cases is 1:1, compared with 12:1 in the United States. Commercial sex workers have an extremely high prevalence_of HIV infection (25 to 88%). Decades ago women and children seemed to be on the periphery of the AIDS epidemic. Today they are at the center of our concern. WHO estimates that more than half of all newly infected adults are women.  On average, worldwide, about one-third of babies born to HIV-infected mothers are themselves infected.

Although no comprehensive surveys have been conducted on medical marijuana users in the United States, small-scale polls indicate that most are seeking relief from symptoms of AIDS. For example, each of the three California cannabis buyers’ clubs—organizations that provide marijuana to patients—visited by the IOM team reported that more than 60 percent of their members requested the drug for AIDS treatment. You may ask, is weed legal in california ?

Mode of transmission

Transmission of HIV occurs through one or more of the three routes: (I) Sexual contact; (2) Parenteral inoculation: (3) Passage of the virus from infected mothers to their newborns. Most venereal transmission i.e., transmission through sexual contact occurred among homosexual men; the risk of such infection increases with the number of sexual partners and with the frequency of anal intercourse which predisposes to rectal abrasion through which the virus-carrying lymphocytes present in the semen enters the recipient’s body. Heterosexual transmission is also on the increase in the United States where female sexual partners of intravenous drug abusers, hemophiliacs, and bisexual males with AIDS are the victims. In Africa heterosexual transmission plays the dominant role. Although male-to-female transmission is firmly established in both the United States and Africa, it seems that unlike in Africa the frequency and risk of female-to-male transmission are not particularly common in the United States. The scenario of general transmission has experienced many changes in different geographical settings and sex practices.


Today three-fourths of all lily infections are due to heterosexual transmission. Parenteral transmission of HIV occurs in three groups of individuals: intravenous drug abusers, hemophiliacs who receive factor VIII concentrates. and random recipients of blood transfusion. Of these groups. the intravenous drug abusers are the largest and they play a major role in the spread of infection. Transmission occurs through the sharing of needles. syringes contaminated with HIV-containing blood. Perinatal transmission may occur transplacental infection in utero by exposure to maternal blood. Studies have indicated that AIDS cannot be transmitted by casual (non­sexual) contact, even within a family where members shared household facilities, including beds, toilets, kitchens, and eating utensils. The risk of occupation-related HIV infection is extremely small; the risk of seroconversion after accidental needlestick exposure in the laboratory is approximately 0.5%, and lower with other forms of exposure involving health workers. It may be mentioned here that is not transmitted through social contacts like shaking hands, social kissing, use of the same toilets, sharing cups, cutleries, crockeries. towels and bed linens, living in the same house or flat or working in the same office or workplace. They should take Diagnosis and Treatment immediately.


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