What is AIDS?
AIDS stands for acquired immunodeficiency syndrome. A person who tests positive for HIV can be diagnosed with AIDS when a laboratory test shows that his or her immune system is severely weakened by the virus or when he or she develops at least one of about 25 different opportunistic infections -- diseases that might not affect a person with a normal immune system but that take advantage of damaged immune systems.

How is HIV detected?
Several different types of laboratory tests can be used to determine whether a person is HIV-positive. It is impossible to look at someone and know whether he or she is HIV-positive. Most tests used to screen for the virus detect HIV antibodies -- proteins the body produces to fight off the infection -- in blood or oral fluid samples.

How does HIV cause AIDS?
HIV destroys CD4+ T cells that are important to the normal function of the human immune system. As the virus destroys these cells, HIV-positive people are susceptible to illnesses that generally do not affect people with healthy immune systems. According to studies including thousands of people, most HIV-positive people are infected with the virus for years before it does enough damage to the immune system to make them susceptible to AIDS-related diseases. Tests are available to measure the amount of HIV in the blood – the viral load – and those with higher viral loads are more likely to develop AIDS-related diseases and to experience a decline in their CD4+ T cells. Reducing the amount of virus in the body with antiretroviral medications can dramatically slow the destruction of a person's immune system and the progression of illness.

Why do some people make statements that HIV does not cause AIDS?
The HIV/AIDS pandemic has attracted much attention both within and outside of the medical and scientific communities, possibly because of the many social issues related to HIV/AIDS, including sexuality, drug use and poverty. Although the scientific evidence is overwhelming and compelling that HIV is the cause of AIDS, the disease process is still not completely understood. This incomplete understanding has led some people to make statements that AIDS is not caused by an infectious agent or is caused by a virus that is not HIV. This is not only misleading, but may have dangerous consequences. Both the U.S. National Institutes of Health and UNAIDS offer explanations of why HIV leads to AIDS:

• NIH How HIV Causes AIDS and The Evidence That HIV Causes AIDS
• UNAIDS Questions & Answers

How long does it take for HIV to cause AIDS?
The time between HIV infection and progressing to AIDS differs for each person and depends on many factors, including a person's health status and their health-related behaviors. With a healthy lifestyle, the time between HIV infection and developing AIDS-related illnesses can be 10 to 15 years, sometimes longer. Antiretroviral therapy can slow the progression of HIV to AIDS by decreasing the amount of virus in a person's body. There also are other medical treatments that can prevent or cure some of the illnesses associated with AIDS, although the treatments do not cure HIV or AIDS. As with other diseases, early detection of HIV infection allows for more options for treatment and preventive health care.

What are some of the symptoms of HIV infection and AIDS?
Once infected with HIV, a person may or may not experience any symptoms. People who do experience symptoms might have a flu-like illness within one or two months after infection. Symptoms can include fever, headache, tiredness and/or enlarged lymph nodes. These symptoms usually disappear within a week to a month and are often mistaken for the symptoms of more common viral infections, like a cold. More persistent or severe symptoms might not appear for several years after a person is first infected with HIV. This period of "asymptomatic" infection is highly individual. Some people might begin to have symptoms within a few months, while others might be symptom-free for more than 10 years.

As the immune system is weakened by HIV, several complications and symptoms could begin to occur. These symptoms might be made worse if the HIV-positive person is not getting the care and services they need. For many people, the first signs of infection are enlarged lymph nodes or "swollen glands" that may be inflamed for several months. As the immune system is weakened by HIV, several complications and symptoms could begin to occur. These symptoms could be made worse if the HIV-positive person is not getting the care and services they need. For many people, the first signs of infection are enlarged lymph nodes or "swollen glands" that may be inflamed for several months. Other symptoms that HIV-positive people might experience months to years before receiving an AIDS diagnosis include:

• Lack of energy
• Weight loss
• Frequent fevers and sweats (sometimes known as "night sweats")
• Persistent or frequent yeast infections (oral or vaginal)
• Persistent skin rashes or flaky skin
• Pelvic inflammatory disease in women that does not respond to treatment
• Short-term memory loss
• Frequent and severe herpes infections that cause mouth, genital, or anal sores, or a painful nerve disease called shingles.

Both men and women experience many of the same symptoms from HIV infection. However, women also experience unique complications that are primarily gynecologic. These could include recurrent vaginal yeast infections, severe pelvic inflammatory disease (PID) or human papillomavirus (HPV) infections. Other vaginal infections might occur more frequently and with greater severity in HIV-positive women (compared with HIV-negative women), including bacterial vaginosis and common sexually transmitted infections such as gonorrhea, chlamydia, and trichomoniasis. HIV-positive women also might experience disruptions or other irregularities in their menstrual cycles.

The signs and symptoms of HIV/AIDS are similar to the symptoms of many other illnesses. The only way to determine HIV infection is to be tested.

Is there a cure for HIV/AIDS?
There is no known cure for HIV/AIDS. There are medical treatments that can slow down the rate at which HIV weakens the immune system. There are other treatments that can prevent or cure some of the illnesses associated with AIDS. Researchers are testing a variety of preventive and curative vaccine candidates, but a successful vaccine likely is years away.

What is the link between HIV and tuberculosis?
The HIV epidemic is largely responsible for the growing number of TB cases in many parts of the world. HIV weakens the cells in the immune system that are needed to fight TB; up to half of all people living with HIV/AIDS eventually develop TB. Worldwide, TB is the leading cause of death among HIV-positive people.

What is the link between HIV and sexually transmitted diseases?
People with a sexually transmitted disease are far more vulnerable than others to becoming infected with HIV. For example, genital ulcers caused by herpes create an entry point for HIV. Even when the STD causes no breaks in the skin or open sores, the infection can cause an immune response in the genital area that can make HIV transmission more likely.

In addition, HIV-positive people are more vulnerable to acquiring sexually transmitted diseases than HIV-negative people because their immune systems are weakened. If an HIV-positive person is infected with another STD, that person is three to five times more likely than other HIV-positive people to transmit HIV through sexual contact.

How is HIV transmitted?
HIV transmission can occur when blood, semen, pre-seminal fluid, vaginal fluid or breastmilk from an HIV-positive person enters the body of an HIV-negative person. HIV can enter the body through a vein, the lining of the anus or rectum, the lining of the vagina and/or cervix, the opening to the penis, the mouth, other mucous membranes -- such as the eyes or inside of the nose -- or cuts and sores. Intact, healthy skin is an excellent barrier against HIV and other viruses and bacteria.

Worldwide, the most common way that HIV is transmitted is through sexual transmission, including anal, vaginal or oral sex with an HIV-positive person. HIV also can be transmitted by sharing needles or injection equipment with an injection drug user who is HIV-positive, or from an HIV-positive woman to her infant before or during birth or through breastfeeding after birth. HIV also can be transmitted through receipt of infected blood or blood clotting factors.

Which body fluids transmit HIV?
Blood, semen, vaginal fluid, breastmilk, and other body fluids containing blood taken from HIV-positive people can contain high concentrations of HIV. The virus also might be present in the fluid surrounding the brain and the spinal cord, fluid surrounding bone joints and fluid surrounding a fetus of an HIV-positive pregnant woman.

HIV has been found in the saliva and tears of some HIV-positive people but in very low quantities. A small amount of HIV in a body fluid does not necessarily mean that HIV can be transmitted by that body fluid. HIV has not been recovered from the sweat of HIV-positive people. Contact with saliva, tears or sweat has never been shown to result in HIV transmission.

How is HIV not transmitted?
HIV is not easily passed from one person to another. The virus does not survive well outside of the body. HIV cannot be transmitted through casual or everyday contact such as shaking hands or hugging. Sweat, tears, vomit, feces and urine do contain small amounts of HIV, but they have not been reported to transmit the disease. Mosquitoes and other insects do not transmit HIV.

How can HIV transmission be prevented?
The best way to avoid HIV infection is to avoid behaviors that would involve exposure to infected body fluids, including unprotected sexual intercourse or sharing needles to inject drugs. If avoiding such behaviors is not possible, numerous health organizations have determined that the use of latex condoms during vaginal, anal or oral intercourse can significantly reduce the risk of HIV transmission; HIV-positive pregnant women can take medications that can reduce the risk of HIV transmission to her child; and injection drug users should not share needles or injection equipment.

How effective are latex condoms in preventing HIV?
Latex condoms, when used consistently and correctly, are highly effective in preventing transmission of HIV. Laboratory studies have found that HIV does not pass through intact latex condoms even when they are stretched or stressed, according to the World Health Organization. Prospective studies looking at couples in which one partner is HIV-positive and the other is not have shown that, with consistent condom use, less than 1% of the HIV-negative people became infected annually. In 2000, representatives of four U.S. government agencies (U.S. Agency for International Development, Food and Drug Administration, Center for Disease Control and Prevention, National Institutes of Health) concluded in a report that, based on an analysis of published studies, male condoms significantly reduce the risk of HIV transmission for both men and women during vaginal intercourse when used correctly in every encounter.

Why is injection drug use a risk for HIV transmission?
At the start of every injection, blood is introduced into the needle and syringe. Therefore, a needle and syringe that an HIV-positive person uses can contain blood that contains the virus. The reuse of a blood-contaminated needle or syringe by another drug injector carries a high risk of HIV transmission because infected blood can be injected directly into the bloodstream.

Sharing other drug-using equipment also can be a risk for spreading HIV. Infected blood can be introduced into drug solutions through using blood-contaminated syringes to prepare drugs; reusing water; reusing bottle caps, spoons, or other containers used to dissolve drugs in water and to heat drug solutions; or reusing small pieces of cotton or cigarette filters used to filter out particles that could block the needle.

Are health care workers at risk of getting HIV on the job?
The risk of health care workers being exposed to HIV on the job is very low, especially if they carefully follow "universal precautions," which are meant to protect them from exposure to all body fluids. The main risk of HIV transmission for health care workers on the job is through accidental injuries from needles and other sharp instruments that might be contaminated with the virus. However, even this risk is small. Scientists estimate that the risk of infection from a needlestick is less than 1%, a figure based on the findings of several studies of health care workers who received punctures from HIV-contaminated needles or were otherwise exposed to HIV-contaminated blood.

If a health care worker is exposed to HIV-contaminated bodily fluid on the job, they can take medications to help reduce their risk of infection. These treatments, called post-exposure prophylaxis, or PEP, usually involve taking a four-week regimen of two or three antiretroviral drugs. The health worker should undergo a baseline test for HIV infection and begin PEP as quickly as possible after the exposure, usually within 36 hours. PEP guidelines are available from the U.S. Centers for Disease Control and Prevention.

Are patients in a health care setting at risk of getting HIV?
While unsafe sexual practices are responsible for the majority of HIV infections worldwide, UNAIDS estimates that unsanitary medical practices -- including the reuse of needles and syringes -- are responsible for as much as 2.5% of HIV cases in sub-Saharan Africa. Although major efforts have been undertaken to improve unsanitary medical practices worldwide, more needs to be done to thoroughly test blood donations and eliminate risky injections. While all countries recognize the importance of blood safety and screen blood for HIV antibodies, in many developing countries screening is routine only in urban settings. Injections should be used only when medically necessary and should be given with single-use equipment that is disposed of safely. Health care workers should practice careful infection control procedures in order to protect patients and themselves from possible HIV infection in medical settings.

Can HIV be transmitted through casual contact (shaking hands, hugging, using a toilet, drinking from the same glass, or sneezing and coughing)?
HIV is not transmitted through day-to-day contact in workplaces, schools, or social settings. HIV is not transmitted through shaking hands, hugging, or casual kissing. A person cannot become infected from touching a toilet seat, a drinking fountain, a door knob, dishes, drinking glasses, food, or pets.

HIV is not an airborne or foodborne virus, and it does not live long outside the body. HIV can be found in blood, semen, or vaginal fluid of an HIV-positive person.

Can HIV be transmitted through mosquitoes?
No, mosquitoes do not transmit HIV. When mosquitoes feed on blood from a person they only inject their saliva, which serves as a lubricant and allows the insect to draw blood more easily. In addition, HIV does not reproduce or survive inside mosquitoes, unlike organisms that are transmitted via insect bites.

How well does HIV survive outside the body?
HIV does not survive for very long outside of the human body. HIV is unable to reproduce outside its living host, except under laboratory conditions. Therefore, it does not spread or maintain infectiousness outside its host.

Where did HIV come from?
In 1999, scientists reported that they had discovered the origin of HIV-1. They identified a subspecies of chimpanzees native to West Equatorial Africa as the original source of the virus. The virus most likely was introduced into the human population when hunters were exposed to the infected blood of non-human primates. More information about the origin of HIV is available from the National Institute of Allergy and Infectious Diseases.

How many people have HIV/AIDS?
UNAIDS estimates that 39.4 million people were living with HIV/AIDS worldwide as of the end of 2004, more than ever before.

What HIV/AIDS statistics are the most reliable?
UNAIDS and the World Health Organization provide the most extensive set of statistics related to the global epidemic. The statistics are compiled in consultation with country-level experts and international epidemiologists. Every country keeps its own record of the number of HIV/AIDS cases and some countries' methods of collecting information are more complete than others. More information about how UNAIDS and WHO calculate HIV/AIDS estimates is available on the UNAIDS Web site.

What do endemic, epidemic and pandemic mean?
Endemic is the constant presence of a disease or infectious agent in a certain geographic area or population group. Epidemic is the rapid spread of a disease in a specific area or among a certain population group. Pandemic is a worldwide epidemic; an epidemic occurring over a wide geographic area and affecting a large number of people.

What is ARV?
ARV stands for antiretroviral. Antiretroviral medications are designed to inhibit the reproduction of HIV in the body. If ARV treatment is effective, the deterioration of the immune system and the onset of AIDS can be delayed for years. It is recommended that ARV drugs be used in combinations of at least three drugs.

What is HAART?
HAART stands for highly active antiretroviral therapy. It is the combination of at least three ARV drugs that attack different parts of HIV or stop the virus from entering blood cells. Even among people who respond well to HAART, the treatment does not get rid of HIV. The virus continues to reproduce but at a slower pace.

What is drug resistance?
Drug resistance occurs when a virus is able to adapt, grow and multiply even in the presence of drugs that usually kill it. Drug resistance reduces the ability of ARV drugs to block the replication of HIV. In some people on HAART, the virus mutates and becomes highly resistant to current medications.

What is ABC in terms of HIV prevention?
ABC stands for Abstinence, Be faithful to a single partner and Condom use. Certain organizations and governments promote the ABC prevention message as a means to stop the spread of HIV.

What is the Global Fund to Fight AIDS, Tuberculosis and Malaria?
The Global Fund to Fight AIDS, Tuberculosis and Malaria, an independent organization, was created to increase resources to fight three of the world's most devastating diseases and to direct those resources to areas of greatest need. The Global Fund -- which is a partnership between governments, civil society, the private sector and affected communities -- was created in 2001 at the urging of U.N. Secretary-General Kofi Annan. Governments, foundations, corporations not-for-profit organizations, and individuals have pledged about $6 billion to the Global Fund, payable through 2008.

What is the 3 by 5 Initiative?
The World Health Organization launched the 3 by 5 Initiative in 2003. The campaign aims to have three million HIV-positive people in developing countries on antiretroviral drug treatment by the end of 2005. According to WHO, of the almost six million HIV-positive people in developing countries who were in need of ARV treatment as of the end of 2004, only 700,000 had access. WHO views the campaign as a step toward achieving universal access to ARV treatment.

What is absorptive capacity?
Absorptive capacity refers to the ability of developing countries to efficiently spend foreign aid money. Given the limitations of health systems in some developing countries, it can be challenging to process, disperse and manage outside assistance, especially since many developing countries receive aid from numerous donors, each with their own preferences and requirements.

How many women in the world today are living with HIV?
UNAIDS estimates that 17.6 million women between the ages of 15 and 49 are living with HIV/AIDS, accounting for nearly half of the almost 40 million HIV cases worldwide, and up from 41% in 1997. In some of the most affected countries and for younger populations, HIV-positive women outnumber HIV-positive men. In sub-Saharan Africa, 57% of adults with HIV are women and young women account for 76% of 15- to 24-year-olds living with HIV. In the regions hardest hit by the epidemic, HIV is up to six times as prevalent among young women as among their male peers.

The number of HIV cases among women is rising in all areas. In higher-income countries, the percentage of HIV-positive women is growing and is most pronounced in marginalized sections of populations, including minorities, immigrants and refugees. In the United States, the proportion of AIDS cases among women has more than tripled since 1986, and HIV is the leading cause of death for African-American women ages 25 to 34.

Why are young women at a higher risk of HIV infection than young men?
Many young women lack information about sexual and reproductive health and disease prevention. In countries with generalized epidemics, the majority of women ages 15 to 24 do not have access to information or resources about reproductive health and HIV/AIDS. Young women may also lack access to health care and education. In addition, young women are among the most vulnerable because their genital tracts have less mature tissue, which may be more easily torn, and they are often victims of coercive or forced sex.

What factors make women more vulnerable?
A combination of biological, social, cultural and economic factors contribute to women's increased vulnerability to HIV infection. In particular, gender inequalities prevent women from asserting power over their own lives and controlling the circumstances that increase their vulnerability to infection, particularly in the context of sexual relationships. Women are also physiologically more susceptible to becoming infected with HIV than men.

What biological factors make women more vulnerable?
Researchers believe that women are biologically more susceptible to HIV infection from heterosexual sex than men. The female genital tract has a greater exposed surface area than the male genital tract; therefore women may be prone to greater risk of infection with every exposure. Male-to-female HIV transmission is estimated to be twice as likely as female-to-male transmission in a single act of vaginal intercourse. Younger women might be even more biologically vulnerable to HIV infection because they have less mature tissue and are often victims of coercive or forced sex.

What social and cultural factors make women more vulnerable?
Social and cultural norms contribute to the unequal status of women in societies, which facilitates the spread of diseases such as HIV. In their sexual relationships, women are often denied the power to make decisions that may lower their risk of HIV infection. Social norms may restrict women's ability to negotiate sex with a condom, demand fidelity in a relationship or seek information about protection, treatment or health care. The unequal power balance between men and women puts women at a greater risk of HIV infection. In some societies, social norms may dictate that women remain monogamous, while men may be allowed and even encouraged to engage in sex with multiple partners.

What economic factors make women more vulnerable?
Poverty and the reliance on men for economic support compound women's risk of HIV infection. Women might engage in unsafe sex or commercial sex work as a means of survival or to support their families. Women’s financial and material dependence on men often makes it difficult or impossible for them to take control of their sexual relationships.

What female-initiated preventive technologies already exist?
Although women make up half of the HIV-positive adults worldwide and HIV is transmitted primarily through heterosexual intercourse worldwide, a female-controlled HIV prevention method currently is not widely available. The female condom is the first and only female-initiated barrier to infection. Unfortunately, many women in developing countries do not have access to the female condom, which is not as readily available as the male condom and often is more expensive. In addition, using the female condom might involve negotiation with a male partner. Microbicides, chemical compounds in the form of gels, films, sponges, lubricants or suppositories that women could use before sex to block HIV transmission, are under development. Microbicides would provide an important new female-controlled preventive technology.

What new preventive technologies are in development?
Researchers currently are developing new technologies such as microbicides and vaccines to help prevent HIV infection. Microbicides are chemical compounds in the form of gels, films, sponges, lubricants or suppositories that women could use before sex to block HIV transmission. An effective microbicide would kill HIV in semen, block the virus from attaching to a target cell or prevent HIV from multiplying if the virus enters a target cell.

A preventive HIV/AIDS vaccine would elicit an immune response to protect the body from HIV infection. A vaccine would be administered orally or more likely through injection. Microbicides and vaccines are tools that potentially could be used without partner negotiation, which could grant women greater power over their own sexual health. It is also a possibility that a partially effective microbicide and a partially effective vaccine could be used in combination to prevent HIV infection. However, it is difficult to estimate how long it will take before an effective microbicide or vaccine is available on the world market, although an effective microbicide probably will be available before a vaccine.

Source www.cdc.gov