Human Immunodeficiency Virus (HIV) is the virus that causes AIDS (Acquired Immune Deficiency Syndrome). Being HIV–positive or having HIV disease is not the same as having AIDS. Many people are diagnosed with HIV but may not get sick for many years. Once in a person's system, HIV begins to attack the immune system and for many who are HIV–positive, over a period of time, they can become ill with a number of conditions.

An HIV–positive person is diagnosed with AIDS when that person has developed certain opportunistic infections or other medical conditions such as a T–cell or CD4 (the most basic element of the immune system) count of less than 200. Only a physician can officially make the diagnosis that a person with HIV now has "AIDS". Generally an AIDS diagnosis occurs many years after infection.

HIV is the virus, AIDS is the disease and "HIV disease" is the most appropriate way to describe the continuum of HIV to AIDS. It is important to note that an AIDS diagnosis does not mean that an individual will soon die. While severe illness can develop, there are many medications available to help treat these. With good medical care it is possible for a person to maintain good health even after an AIDS diagnosis.

Transmission of HIV almost always occurs through unprotected sex, or by sharing needles. If people think they have been exposed to the HIV virus they should get an HIV test. 
The most commonly used test is a blood test that looks for antibodies to the virus. Antibodies are produced by the immune system to fight the virus. The "window period" is the time that it takes for the antibodies to develop after being exposed. Although many people develop antibodies within the first month of their infection, some people take a bit longer. Clinicians agree that testing at three months after exposure will give a conclusive result. 
All pregnant women should be tested for HIV so they can be treated prenatally and greatly reduce the risk of transmitting HIV to their babies.
People can get tested for HIV by their regular doctor, or they can go to a health facility, or a clinic that specializes in sexual health. There is now a rapid blood test for HIV that requires only a few drops of blood and gives same day results. It is especially important to practice abstinence or safe sex and to avoid sharing needles during the window period in order to get an accurate HIV test result, and to avoid the risk of infecting another person since newly infected people are especially infectious to others.

We tend to think of "disease" in simple terms: infection equals illness. It's a little different with HIV since the virus can cause slow, subtle damage to the immune system long before an infected person will feel ill. Most health care providers use the term "HIV disease" to identify the variety of changes a person may experience, from initial infection to more advanced stages of serious, life–threatening illness. The term describes the medical condition of anyone infected with the virus, regardless of his or her symptoms.


HIV reproduces continuously in the body from the first day of infection. A person who is infected with HIV will typically produce about 10 billion new HIV particles each day, and about 2 billion virus–fighting immune system cells—CD4 T cells—are produced and destroyed.

A person's immune system attacks HIV soon after infection, and at first is able to clear a large amount of virus from the body every 24 hours. However, for each virus particle cleared, at least one new one is created. The body's initial, vigorous anti–HIV response creates a temporary equilibrium between immune cells and the virus that may last for months or years.

Typically, a person will show no outward signs of illness during this time, except for severe flu–like symptoms after the initial infection as a sign that the immune system is kicking–in to fight off HIV.
Over time, however, the virus gains the upper hand. The amount of HIV in the body (viral load) increases and the CD4 T cell count declines.

The immune system cannot work properly under constant attack from HIV. Eventually, the virus overwhelms the defenses of the immune system, which then can no longer ward off other illness–causing infections, some of which can be life threatening.


Yes. All blood in blood banks has been tested for HIV, hepatitis and other infectious agents. Even in high prevalence areas where many people with HIV live, the risk of transmission through a blood or blood produced transfusion is infinitesimal

No. Numerous studies have shown no evidence of HIV transmission through mosquitoes. These studies showed that transmission via mosquitoes is not possible because:
Mosquitoes do not ingest enough HIV–infected blood to transmit HIV to another person. The small amount of the virus ingested by mosquitoes is not substantial enough to cause HIV infection in another person.
Mosquitoes digest HIV. The virus cannot survive inside the insect and it cannot be passed on to the mosquito's next host.
Mosquitoes are not flying hypodermic needles. A mosquito's complex feeding apparatus does not involve any exchange of blood between the mosquito and host.

Correct and consistent use of a latex barrier for protection during sex greatly reduces the risk of transmitting HIV. They also reduce the risk of spreading other sexually transmitted diseases. Latex is the most common material for condoms. Viruses cannot get through it. Never use oil–based lubricants like hand or body lotion. These can cause tears and leaks in the latex causing it to break.
Condoms must be stored, used and disposed of correctly. Also, observe the expiration date on the package and tear it open carefully. Avoid opening by tearing the package with your teeth or using a scissors as tiny cuts may be made in the condom. Never use a product that has been previously used or exposed to extreme temperatures.


Abstaining from sexual activity with others can eliminate the risk of becoming infected with HIV. Be aware that using drugs or alcohol can impair judgment and make it difficult to maintain abstinence or ultimately practice safer sex. Learn about sexual activities that can reduce the risk of HIV transmission by avoiding exposure to semen or vaginal fluid. For many, abstinence is a practical and useful choice, however for others it is not an option so learning about the correct and consistent usage of condoms and latex barriers during sex greatly reduces the risk of contracting HIV


Research has shown that HIV transmission is two to five times more likely to occur when another sexually transmitted disease is present. If the STD causes sores or irritation in the skin it can be easier for HIV to enter the body. Even if the STD does not cause open sores or irritation it can stimulate an immune response that can make HIV transmission more likely. Most STDs can be detected by testing within a few weeks after exposure, and many are treatable or curable.


Sharing syringes is a high risk behavior for HIV since a contaminated syringe can pass blood directly from one person's bloodstream to another. Blood can enter a syringe when it is placed into the vein. Some of this blood remains in the syringe after use and can enter to bloodstream of others if the needle is shared. Sharing syringes is also a high risk for hepatitis transmission.