WHAT IS HIV?
“HIV” stands for Human Immunodeficiency Virus. To understand what that means, let’s break it down:
- H – Human – This particular virus can only infect human beings.
- I – Immunodeficiency – HIV weakens your immune system by destroying important cells that fight disease and infection. A "deficient" immune system can't protect you.
- V – Virus – A virus can only reproduce itself by taking over a cell in the body of its host.
HIV is a lot like other viruses, including those that cause the "flu" or the common cold. But there is an important difference – over time, your immune system can clear most viruses out of your body. That isn't the case with HIV – the human immune system can't seem to get rid of it. That means that once you have HIV, you have it for life.
We know that HIV can hide for long periods of time in the cells of your body and that it attacks a key part of your immune system – your T-cells or CD4 cells. Your body has to have these cells to fight infections and disease, but HIV invades them, uses them to make more copies of itself, and then destroys them.
Over time, HIV can destroy so many of your CD4 cells that your body can't fight infections and diseases anymore. When that happens, HIV infection can lead to AIDS, the final stage of HIV infection.
However, not everyone who has HIV progresses to AIDS. With proper treatment, called “antiretroviral therapy” (ART), you can keep the level of HIV virus in your body low. ART is the use of HIV medicines to fight HIV infection. It involves taking a combination of HIV medicines every day. These HIV medicines can control the virus so that you can live a longer, healthier life and reduce the risk of transmitting HIV to others. Before the introduction of ART in the mid-1990s, people with HIV could progress to AIDS in just a few years. Today, a person who is diagnosed with HIV and treated before the disease is far advanced can have a nearly normal life expectancy.
No safe and effective cure for HIV currently exists, but scientists are working hard to find one, and remain hopeful.
“AIDS” stands for Acquired Immunodeficiency Syndrome. To understand what that means, let’s break it down:
- A – Acquired – AIDS is not something you inherit from your parents. You acquire AIDS after birth.
- I – Immuno – Your body's immune system includes all the organs and cells that work to fight off infection or disease.
- D – Deficiency – You get AIDS when your immune system is "deficient," or isn't working the way it should.
- S – Syndrome – A syndrome is a collection of symptoms and signs of disease. AIDS is a syndrome, rather than a single disease, because it is a complex illness with a wide range of complications and symptoms.
As noted above, AIDS is the final stage of HIV infection, and not everyone who has HIV advances to this stage. People at this stage of HIV disease have badly damaged immune systems, which put them at risk for opportunistic infections (OIs).
You are considered to have progressed to AIDS if you have one or more specific OIs, certain cancers, or a very low number of CD4 cells. If you have AIDS, you will need medical intervention and treatment to prevent death.
For more information, see CDC’s HIV/AIDS Basics.
Certain body fluids from an HIV-infected person can transmit HIV.
These body fluids are:
- Blood
- Semen (cum)
- Pre-seminal fluid (pre-cum)
- Rectal fluids
- Vaginal fluids
- Breast milk
HOW DO YOU GET HIV OR AIDS?
These body fluids must come into contact with a mucous membrane or damaged tissue or be directly injected into your bloodstream (by a needle or syringe) for transmission to possibly occur. Mucous membranes are the soft, moist areas just inside the openings to your body. They can be found inside the rectum, the vagina or the opening of the penis, and the mouth.
For more information, see CDC’s HIV Basics: HIV Transmission.
Approximately 50,000 new HIV infections occur in the United States each year. In the U.S., HIV is spread mainly by:
- Having sex with someone who has HIV. In general:
- Anal sex (penis in the anus of a man or woman) is the highest-risk sexual behavior. Receptive anal sex (“bottoming”) is riskier than insertive anal sex (“topping”).
- Vaginal sex (penis in the vagina) is the second highest-risk sexual behavior.
- Having multiple sex partners or having sexually transmitted infections can increase the risk of HIV infection through sex.
- Sharing needles, syringes, rinse water, or other equipment (“works”) used to prepare injection drugs with someone who has HIV.
Less commonly, HIV may be spread by:
- Being born to an infected mother. HIV can be passed from mother to child during pregnancy, birth, or breastfeeding.
- Being stuck with an HIV-contaminated needle or other sharp object. This is a risk mainly for health care workers.
- Receiving blood transfusions, blood products, or organ/tissue transplants that are contaminated with HIV. This risk is extremely small because of rigorous testing of the US blood supply and donated organs and tissues.
- Eating food that has been pre-chewed by an HIV-infected person. The contamination occurs when infected blood from a caregiver’s mouth mixes with food while chewing, and is very rare.
- Being bitten by a person with HIV. Each of the very small number of documented cases has involved severe trauma with extensive tissue damage and the presence of blood. There is no risk of transmission if the skin is not broken.
- Oral sex—using the mouth to stimulate the penis, vagina, or anus (fellatio, cunnilingus, and rimming). Giving fellatio (mouth to penis oral sex) and having the person ejaculate (cum) in your mouth is riskier than other types of oral sex.
- Contact between broken skin, wounds, or mucous membranes and HIV-infected blood or blood-contaminated body fluids. These reports have also been extremely rare.
- Deep, open-mouth kissing if the person with HIV has sores or bleeding gums and blood is exchanged. HIV is not spread through saliva. Transmission through kissing alone is extremely rare.
HIV is NOT spread by:
- Air or water
- Insects, including mosquitoes or ticks
- Saliva, tears, or sweat
- Casual contact, like shaking hands, hugging or sharing dishes/drinking glasses
- Drinking fountains
- Toilet seats
HIV is not spread through the air and it does not live long outside the human body.
Having an undetectable viral load greatly lowers the chance that a person living with HIV can transmit the virus to a partner, but there is still some risk. “Viral load” refers to the amount of HIV in an infected person’s blood. An “undetectable viral load” is when the amount of HIV in a person’s blood is so low that it can’t be measured. antiretroviral therapy (ART) reduces a person’s viral load, ideally to an undetectable level, when taken consistently and correctly. However, a person with HIV can still potentially transmit HIV to a partner even if they have an undetectable viral load, because:
- HIV may still be found in a person’s genital fluids (e.g., semen, vaginal fluids). The viral load test only measures virus in a person’s blood.
- A person’s viral load may go up between tests. When this happens, they may be more likely to transmit HIV to partners.
- Sexually transmitted diseases (STDs) increase viral load in a person’s genital fluids.
For more information on how HIV is spread, see CDC’s HIV Basics: HIV Transmission.
Also, for more information about the risks from different types of HIV exposure, see CDC’s HIV Transmission Risk.
The terms “HIV” and “AIDS” can be confusing because both terms refer to the same disease. However, “HIV” refers to the virus itself, and “AIDS” refers to the late stage of HIV infection, when an HIV-infected person’s immune system is severely damaged and has difficulty fighting diseases and certain cancers. Before the development of certain medications, people with HIV could progress to AIDS in just a few years. But today, most people who are HIV-positive do not progress to AIDS. That’s because if you have HIV and you take antiretroviral therapy (ART) consistently, you can keep the level of HIV in your body low. This will help keep your body strong and healthy and reduce the likelihood that you will ever progress to AIDS. It will also help lower your risk of transmitting HIV to others.
For more information about the difference between HIV and AIDS, see What Is HIV/AIDS?
The only way to know for sure if you have HIV is to get tested.
Testing is relatively simple. You can get an HIV test from your doctor or healthcare provider, community health center, Veteran’s health center, Title X family planning clinic, and other locations. There also are FDA-approved HIV home test kits you can use.
One of the easiest ways to find an HIV testing location is to use the HIV Testing & Care Services Locator. Just type in your ZIP code and, within seconds, you will get a list of HIV testing sites near you—including those that offer free HIV testing!
SIGNS & SYMPTOMS
The symptoms of HIV vary, depending on the individual and what stage of the disease you are in.
Within 2-4 weeks after HIV infection, many, but not all, people experience flu-like symptoms, often described as the “worst flu ever.” This is called “acute retroviral syndrome” (ARS) or “primary HIV infection,” and it’s the body’s natural response to the HIV infection.
Symptoms can include:
- Fever (this is the most common symptom)
- Swollen glands
- Sore throat
- Rash
- Fatigue
- Muscle and joint aches and pains
- Headache
These symptoms can last anywhere from a few days to several weeks. However, you should not assume you have HIV if you have any of these symptoms. Each of these symptoms can be caused by other illnesses. Conversely, not everyone who is infected with HIV develops ARS. Many people who are infected with HIV do not have any symptoms at all for 10 years or more.
You cannot rely on symptoms to know whether you have HIV. The only way to know for sure if you are infected with HIV is to get tested. If you think you have recently been exposed to HIV—if you have had oral, vaginal or anal sex without a condom with a known HIV positive person or a partner whose HIV status you do not know or shared needles to inject drugs—get an HIV test. Traditional HIV tests detect HIV antibodies. But during this early stage your body is not yet producing these antibodies. A new HIV test was approved in 2013 that can detect the presence of HIV in your body during this early stage of infection. So no matter where you get tested, it is very important to let your provider know that you may have been recently infected with HIV and you would like to be tested for acute HIV. Use the HIV/AIDS Testing and Services Locator to find a HIV testing site near you or enter your location here:
It is important to remember that with or without symptoms, you are at particularly high risk of transmitting HIV to your sexual or drug using partners during this time because the levels of HIV in your blood stream are very high. For this reason, it is very important to take steps to reduce your risk of transmission.
After the early stage of HIV infection, the disease moves into a stage called the “clinical latency” stage. “Latency” means a period where a virus is living or developing in a person without producing symptoms. During the clinical latency stage, people who are infected with HIV experience no HIV-related symptoms, or only mild ones. (This stage is sometimes called “asymptomatic HIV infection” or “chronic HIV infection.”)
During the clinical latency stage, the HIV virus reproduces at very low levels, although it is still active. If you takeantiretroviral therapy (ART), you may live with clinical latency for several decades because treatment helps keep the virus in check. (Read more about HIV treatment.) For people who are not on ART, this clinical latency stage lasts an average of 10 years, but some people may progress through this phase faster.
It is important to remember that people in this symptom-free period are still able to transmit HIV to others even if they are on ART, although ART greatly reduces the risk of transmission.
Again, the only way to know for sure if you are infected with HIV is to get tested. Tests are available that can detect the virus at this stage. Use the HIV/AIDS Testing and Services Locator to find a HIV testing site near you.
If you have HIV and you are not taking HIV medication (antiretroviral therapy), eventually the HIV virus will weaken your body’s immune system. The onset of symptoms signals the transition from the clinical latency stage to AIDS (Acquired Immunodeficiency Syndrome).
During this late stage of HIV infection, people infected with HIV may have the following symptoms:
- Rapid weight loss
- Recurring fever or profuse night sweats
- Extreme and unexplained tiredness
- Prolonged swelling of the lymph glands in the armpits, groin, or neck
- Diarrhea that lasts for more than a week
- Sores of the mouth, anus, or genitals
- Pneumonia
- Red, brown, pink, or purplish blotches on or under the skin or inside the mouth, nose, or eyelids
- Memory loss, depression, and other neurologic disorders.
Each of these symptoms can be related to other illnesses. So, as noted above, the only way to know for sure if you are infected with HIV is to get tested.
Many of the severe symptoms and illnesses of HIV disease come from the opportunistic infections that occur because your body’s immune system has been damaged. (Read more about opportunistic illnesses.)
