HIV DISEASE

HIV & AIDS
High Risk Behaviour
HIV Disease Progression

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HIV
HIV means HUMAN IMMUNO DEFICIENCY VIRUS the virus that causes AIDS.

HIV is synonymous with the AIDS virus; HIV is correct medical term, but it is often called the AIDS virus by common people.

HIV is classed as a retrovirus - a group of viruses which has the ability to replicate their own genetic material, so when you test positive for HIV it means your body has developed antibodies in response to the virus entering your body. HIV is the virus that develops into AIDS.

AIDS
AIDS means ACQUIRED IMMUNO DEFICENCY SYNDROME and the acronym AIDS stands for combination of symptoms, which attack the body after the immune system, is damaged by the virus known as HIV.

AIDS is a fatal syndrome because the progressive damage to the body's immune system leaves people highly susceptible to contracting diseases. This diseases are known as opportunistic infections, because of this AIDS cannot properly be called as a disease, but a syndrome.

Definition of AIDS
The Center for Disease Control CDC) currently defines AIDS in an adult or adolescent age 13 years or older as the presence of one of 25 conditions indicative of severe immuno suppression associated with HIV infection, such as Pneumocystis carinii pneumonia (PCP), or HIV infection in an individual with a CD4+ or T cell count less than 200/cells per cubic millimeter (mm3) of blood. In children younger than 13 years, the definition of AIDS is similar to that in adolescents and adults, except that lymphoid interstitial pneumonitis and recurrent bacterial infections are included in the list of AIDS-defining conditions.

The designation "AIDS" is a surveillance tool. Surveillance definitions of AIDS have proven useful epidemiologically to track and quantify the recent epidemic of HIV-mediated immuno suppression and its manifestations. However, AIDS represents only the end stage of a continuous, progressive pathogenic process, beginning with primary infection with HIV, continuing with a chronic phase that is usually asymptomatic, and leading to progressively severe symptoms and, ultimately, profound immunodeficiency and opportunistic infections and cancers.

So things like pneumonia could become potentially deadly to some one with AIDS. However you don't get AIDS. Your body becoming infected by a virus called the HIV and causes the condition. When you have AIDS, you are in the late stages of HIV disease, and have probably had some serious illnesses as a result of the HIV in your body. At this stage in HIV disease, your immune system is very weak, and it becomes difficult for you to fight off infections that would not affect most people.

HOW IS HIV TRANSMITTED?

HIV virus is transmitted through a person who has contracted HIV and has yet to experience or show any symptoms.Male / Female can transmit HIV to others in specific ways only. HIV is found in Blood, Sperm and Vaginal secretions of infected people in sufficient quantity to infect other people. It is not particularly easily transmitted; only if HIV in the blood or body fluids enters the blood stream of another person.

The following table will show:

HIV doesn't survive for long in the open and it can't stand high temperatures. Though tears and saliva are technically body fluids like sperm and blood, no one has been found to have contracted the HIV virus through kissing or coming into contact with someone's tears. Normal everyday contact with an infected person is perfectly safe, like touching or non-intimate kissing. And you can't get HIV by touching things like cups, towels and toilet seats, which have been used by an infected person. Not sharing injections and if you are sexually active by practicing safer sex that is using condoms of high quality reduces your chances of contracting the virus.

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High Risk Behavior is behavior, which can facilitate the spread of HIV such as:

You may have been infected with HIV, and can infect others, in a number of ways:

The best way to prevent HIV from spreading is not to engage in high risk behavior that is to prevent body fluids infected with HIV from entering the body. Which are as follows:

When HIV first enters your body your viral load is probably high. This period is called primary infection. Your immune system has not responded yet to the HIV infection and an HIV antibody test reads HIV negative. When your body starts to fight back, it brings down the amount of virus in your body to what is called a "set point". This set point is different for everyone. Some people have high viral loads, in the hundreds of thousands or more, while others have viral loads of a few hundred, and anything between these extremes. This may be because each of us has a different immune system that fights off HIV more or less effectively. It also could be because of the different strains of HIV, or your genetic make-up. Most people believe it's because of a combination of all of these things. Seroconversion is when antibodies to HIV are produced by your body. Antibodies are disease-fighting cells made by your immune system to fight off or destroy viruses, poisons or bacteria in your body. This occurs in most people within six months of infection by HIV. Some people experience illness during early infection, others do not experience any illness when they seroconvert. Early illness may include any or all of flu-like symptoms, diarrhea, headache, swollen glands, night sweats and other symptoms.

After the viral load set point has settled, there is a period of when you will not experience any illness, infections or diseases because of HIV. The virus however is still inside you, making billions of copies of itself daily. At the same time, your immune system is fighting to keep your body in good health, and fighting off the HIV. This period can last anywhere from eighteen months in some people, to over 18 years in others.

In advanced HIV disease, your viral load count increases and your CD4 cells get killed off. If your CD4 cell count drops below 200 you are at risk of developing many types of OIs, the infections related to HIV. Serious, life-threatening infections may occur at this time.

Advances in anti-HIV treatments, and how best to use them, are improving steadily over time. The ability to slow, or possibly even stop progression of HIV disease is allowing some people to live longer, healthier lives, increasing hope for a long and healthy future living with HIV.
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HIV like other viruses infects certain type of cells of the body. HIV has a particular chemical attraction to the CD-4 / T4 / T cells. Once HIV gets into a cell it can take over the genetic material of the cell and turn the cell into a factory for producing more HIV. The newly produced HIV is then released and goes in to infect more cells. The more HIV that is released, the more new cells are likely to become infected.

HIV disease has a number of stages, they are as follows:

Although people may not experience any symptoms during stage 2, HIV is slowly damaging the immune system. When enough damage to the immune system has occurred people will start to experience symptoms of HIV disease and may progress to HIV stage 3 or 4 (AIDS)

Evidence That HIV Causes AIDS Before the appearance of HIV, AIDS-like syndromes were rare; today, they are common in HIV-infected individuals. Prior to the appearance of HIV, AIDS-related conditions such as Pneumocystis carinii pneumonia (PCP), Kaposi's sarcoma (KS) and disseminated infection with the Mycobacterium avium complex (MAC) were extraordinarily rare in the United States. In a 1967 survey, only 107 cases of PCP in this country had been described in the medical literature, virtually all among individuals with underlying immunosuppressive conditions. Before the AIDS epidemic, the annual incidence of Kaposi's sarcoma in the United States was 0.021 to 0.061 per 100,000, and only 32 individuals with disseminated MAC disease had been described in the medical literature. By December 31, 1994, physicians had reported to the CDC 127,626 patients with AIDS in the United States with definitive diagnoses of PCP, 36,693 with KS and 28,954 with disseminated MAC.

Historically, the occurrence of AIDS-like illnesses in populations has closely followed the appearance of HIV. The first cases of AIDS in homosexual men in San Francisco were detected in 1981, and retrospective examination of frozen blood samples from a cohort of gay men showed the presence of HIV antibodies as early as 1978 but not before then. Subsequently, in every country and city where AIDS has appeared, evidence of HIV infection has preceded AIDS by just a few years. In Thailand, for example, the explosion of AIDS cases followed a dramatic increase in HIV seroprevalence rates.

Many studies agree that only a single factor, HIV, predicts whether a person will develop AIDS.

There are incidences when health care providers have also got infected and had to be treated with PEP,which is an expensive treatment and not a regime in many places.

Other viral infections, bacterial infections, sexual behavior patterns and drug abuse patterns do not predict who develops AIDS. Individuals from diverse backgrounds, including heterosexual men and women, homosexual men and women, hemophiliacs, sexual partners of hemophiliacs and transfusion recipients, injection-drug users and infants have all developed AIDS, with the only common denominator being their infection with HIV.

Numerous sero surveys show that AIDS is common in populations where many individuals have HIV antibodies. Conversely, in populations with low seroprevalence of HIV antibodies, AIDS is extremely rare.For example, Malawi, an African country with high seroprevalence of HIV antibodies, had reported 34,167 cases of AIDS to the WHO as of December 31, 1994. In contrast, Madagascar, an island country off the southeast coast of Africa with a very low seroprevalence of HIV antibodies, reported only 9 cases of AIDS to the WHO through December 31, 1994.

In cohort studies, severe immunosuppression and AIDS-defining illnesses occur exclusively in individuals who are HIV-infected. Conversely, matched controls, individuals with similar lifestyles but without HIV infection, virtually never suffer these symptoms.For example, in one cohort in Vancouver, investigators followed 715 homosexual men for a median of 8.6 years. Every case of AIDS in this cohort occurred in individuals who were positive for HIV antibodies. No AIDS-defining illnesses occurred in men who remained negative for HIV antibodies, despite the fact that these men had appreciable patterns of illicit drug use and receptive anal intercourse.

The specific immunologic profile that typifies AIDS -- a persistently low CD4+ T cell count -- is extraordinarily rare in the absence of HIV infection or other known cause of immunosuppression.

For example, in the NIAID-supported Multicenter AIDS Cohort Study (MACS), 22,643 CD4+ T cell determinations in 2,713 HIV-seronegative homosexual men revealed only one individual with a CD4+ T cell count persistently lower than 300 cells/mm3, and this individual was receiving immunosuppressive therapy.

Nearly everyone with AIDS has antibodies to HIV. A recent survey of 230,179 AIDS patients in the United States revealed only 299 HIV-seronegative individuals. An evaluation of 172 of these 299 patients found 131 actually to be seropositive; an additional 34 died before their serostatus could be confirmed.

HIV can be detected in virtually everyone with AIDS.

Recently developed sensitive testing methods, including the polymerase chain reaction (PCR) and improved culture techniques, have enabled researchers to find HIV in patients with AIDS with few exceptions. HIV has been repeatedly isolated from the blood, semen and vaginal secretions of patients with AIDS, findings consistent with the epidemiologic data demonstrating AIDS transmission via sexual activity and contact with infected blood.

HIV fulfills Koch's postulates as the cause of AIDS. Koch's postulates of disease causation stipulate that an infectious agent must be found in all cases of the disease, the agent must be isolated from the host's body, the agent must cause disease when injected into healthy hosts, and the same agent must once again be isolated from the newly diseased host.

All four postulates have been fulfilled in three laboratory workers with no other risk factors who have developed AIDS or severe immunosuppression after accidental exposure to concentrated, cloned HIV in the laboratory. Two individuals were infected in 1985 and one in 1991. All three have shown marked CD4+ T cell depletion, and two have CD4+ T cell counts that have dropped below 200/mm3 of blood. One of these latter individuals developed PCP, an AIDS indicator disease, 68 months after showing evidence of infection, and did not receive an antiretroviral drug until 83 months after the infection. In all three cases, HIV was isolated from the infected individual, sequenced and shown to be the infecting strain of virus.

In addition, through 1994 the CDC had received reports of 42 health care workers in the United States with documented, occupationally acquired HIV infection, of whom 17 have developed AIDS in the absence of other risk factors. The development of AIDS following known HIV seroconversion also has been repeatedly observed in pediatric and adult blood transfusion cases, in mother-to-child transmission, and in studies of hemophilia, injection-drug use and sexual transmission in which seroconversion can be documented using serial blood samples.

Newborn infants have no behavioral risk factors, yet 6,209 children in the United States developed AIDS through December 31, 1994.

Only the 15 to 40 percent of infants who become HIV-infected before or during birth go on to develop immunosuppression and AIDS. Babies who are not HIV-infected do not develop AIDS.

Because many HIV-infected mothers abuse recreational drugs, some have argued that maternal drug use itself causes pediatric AIDS. However, studies have consistently shown that babies who are not HIV-infected do not develop AIDS, regardless of their mothers' drug use.

The HIV-infected twin develops AIDS while the uninfected twin does not. Researchers have documented cases of HIV-infected mothers who have given birth to twins, one of whom is HIV-infected and the other not. The HIV-infected children developed AIDS, while the other children remained clinically and immunologically normal.

Since the appearance of HIV, mortality has increased dramatically among hemophiliacs.

The impact of HIV on the life expectancy of hemophiliacs has been dramatic. Among those with severe factor-VIII deficiency, mortality increased six-fold from 1981 to 1990. Median life expectancy at one year of age for males with hemophilia increased from 40.9 years at the beginning of the century (1900 to 1920) to a high of 68 years after the introduction of factor therapy (1971 to 1980). In the era of AIDS (1981 to 1990), life expectancy declined to 49 years.

Studies of transfusion-acquired AIDS cases have repeatedly led to the discovery of HIV in the patient as well as in the blood donor.

Numerous studies have shown an almost perfect correlation between the occurrence of AIDS in a blood recipient and donor, and evidence of homologous HIV strains in both the recipient and the donor.

10 to 20 % of wives and sex partners of male HIV-positive hemophiliacs in the United States are also HIV-infected. Through December 31, 1994, the CDC had received reports of 266 cases of AIDS in those whose only risk factor was sex with an HIV-infected person with hemophilia. The CDC had also received reports of 628 cases of AIDS in individuals whose primary risk factor was sex with an HIV-infected transfusion recipient.

HIV infects and is responsible for the death of CD4+ T lymphocytes in vitro and in vivo.

CD4+ T cells are the cells depleted in people with AIDS. Although the loss of CD4+ T cells is not the only immune defect seen in people with AIDS, the observation that HIV also infects and damages these cells in vitro establishes an obvious link between HIV and AIDS. Recent in vivo studies suggest that during HIV infection, more than 1 billion CD4+ T cells are destroyed every day, eventually overwhelming the immune system's regenerative capacity.

HIV damages the body's sources of CD4+ T cells and centers of immune activity. HIV destroys precursor cells and the structures in the bone marrow and thymus that are needed for the development of mature immune cells. This damage may help explain why the immune systems of people with AIDS do not successfully regenerate their CD4+ T cells. The virus also progressively destroys the lymph nodes, the centers of immune activity in the body. Significantly, in the approximately 5 percent of HIV-infected people whose disease does not progress, the lymph node architecture appears to remain intact.

Studies of HIV-infected people show that increasing amounts of HIV in the body correlate with the progression of the immunologic processes that lead to AIDS.

As levels of viral replication and the amount of virus in the body increase, so too do the various immunologic processes associated with AIDS. Recent studies have shown that a rise in expression of HIV RNA in peripheral blood mononuclear cells precedes clinically defined progression of disease in people with HIV.

In the approximately 5 percent of HIV-infected individuals whose disease progresses very slowly, the amount of virus in the blood and lymph nodes is significantly lower than that in HIV-infected people whose disease progression is more typical.

HIV is similar in genetic structure and morphology to other lentiviruses that often cause immunodeficiency in their animal hosts in addition to slow, progressive wasting disorders, neurodegeneration and death.

Like HIV in humans, animal viruses such as feline immunodeficiency virus (FIV) in cats, visna virus in sheep and simian immunodeficiency virus (SIV) in monkeys primarily infect cells of the immune system such as T cells and macrophages. For example, visna virus infects macrophages and causes a slowly progressive neurologic disease.

Baboons develop AIDS after inoculation with clones of an HIV variant that also causes AIDS in humans.

Over the course of two years, baboons infected with HIV-2 exhibited a significant decline in immune function, as well as AIDS-like symptoms. Asian monkeys develop AIDS after infection with the simian immunodeficiency virus (SIV), a virus closely related to HIV.

In macaque species, various cloned SIV isolates induce syndromes that parallel HIV infection and AIDS in humans, including swollen lymph nodes early in infection, CD4+ T cell depletion, opportunistic infections such as PCP and MAC, and death.