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HIV / AIDS
More than 1.1 million people in the United States
are living with HIV infection, and almost 1 in 5
(18.1%) are unaware of their infection.
HIV/AIDS Fast Facts
The CDC estimates that 1,148,200 persons aged 13 years and older are living with HIV
infection, including 207,600 (18.1%) who are unaware of their infection .
Over the past decade, the number of people living with HIV has increased, while the annual
number of new HIV infections has remained relatively stable.
HIV Incidence (new infections): about 50,000 new HIV infections per year.
HIV Diagnoses (new diagnoses, regardless of when infection occurred): In 2011, an estimated
49,273 people were diagnosed with HIV infection in the United States. In that same year, an
estimated 32,052 people were diagnosed with AIDS. Since the epidemic began, an estimated
1,155,792 people in the United States have been diagnosed with AIDS.
Deaths: An estimated 15,529 people with an AIDS diagnosis died in 2010, and approximately
636,000 people in the United States with an AIDS diagnosis have died since the epidemic
began. The deaths of persons with an AIDS diagnosis can be due to any cause—that is, the
death may or may not be related to AIDS.
What is HIV?
HIV stands for human immunodeficiency virus. It is the virus that can lead to
acquired immunodeficiency syndrome, or AIDS.
Unlike some other viruses, the human body cannot get rid of HIV. That means that once you
have HIV, you have it for life.
HIV is a virus spread through body fluids that affects specific cells of the immune system,
called CD4 cells, or T cells.
Over time, HIV can destroy so many of these cells that the body can’t fight off infections and
disease. When this happens, HIV infection leads to AIDS.
How HIV/AIDS Affects the Immune System
• HIV attacks the bodies immune system by destroying lymphocytes (specialized white blood
cells that perform many immune functions)
• There are two types of lymphocytes: B cells and T cells.
• Helper T cells stimulate B cells to produce antibodies, which help destroy pathogens in the
body.
• When HIV enters certain cells, including lymphocytes, it reproduces itself and eventually
destroys the cell.
• As more cells are destroyed, the immune system becomes weaker and weaker.
• The body then becomes vulnerable to opportunistic illnesses- infections the body could fight
off if the immune system were healthy.
How HIV Attacks Cells
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HIV attaches to cell surface
Virus core enters cell and goes to nucleus
Virus makes a copy of its genetic material
New virus assembles at cell surface
New virus breaks away from host cell
Where did HIV come from?
Scientists identified a type of chimpanzee in West Africa as the source of HIV
infection in humans.
They believe that the chimpanzee version of the immunodeficiency virus (called
simian immunodeficiency virus, or SIV) most likely was transmitted to humans and
mutated into HIV when humans hunted these chimpanzees for meat and came into
contact with their infected blood.
Studies show that HIV may have jumped from apes to humans as far back as the late
1800s. Over decades, the virus slowly spread across Africa and later into other parts
of the world. We know that the virus has existed in the United States since at least
the mid- to late 1970s.
How is HIV passed from person to person?
Only certain fluids from an HIV-infected person can transmit HIV
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blood
semen, pre-seminal fluid
rectal fluids
vaginal fluids
breast
These fluids must come in contact with a mucous membrane or damaged tissue or be
directly injected into the bloodstream (from a needle or syringe) for transmission to possibly
occur. Mucous membranes can be found inside the rectum, the vagina, the opening of the
penis, and the mouth.
In the United States, HIV is spread mainly by:
• unprotected sex (sex without a condom) with someone who has HIV
o anal sex which is the highest-risk sexual behavior
o vaginal sex is the second highest-risk sexual behavior.
• having multiple sex partners or having other sexually transmitted infections can
increase the risk of infection through sex
• Sharing needles, syringes, rinse water, or other equipment 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.
• Receiving blood transfusions, blood products, or organ/tissue transplants that are
contaminated with HIV.
• 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— (mouth to penis oral sex) and ejaculating in the 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:
• day-to-day contact in the workplace, schools, or social settings
• shaking hands, hugging, or a casual kiss
• toilet seat, a drinking fountain, a door knob, dishes, drinking glasses, food, cigarettes, pets,
or insects
• through the air (does not live long outside the body)
• saliva, and there is no documented case of transmission from an HIV-infected person
spitting on another person
• scratching because there is no transfer of body fluids between people.
• mosquitoes or any other insects, HIV does not reproduce (and does not survive) in insects.
• tattooing or body piercing- they do present a potential risk of HIV transmission, but no cases
of HIV transmission from these activities have been documented.
• food- The virus does not live long outside the body. You cannot get it from consuming food
handled by an HIV-infected person; even if the food contained small amounts of HIVinfected blood or semen, exposure to the air, heat from cooking, and stomach acid would
destroy the virus.
HIV does not survive long outside the human body (such as on surfaces), and it cannot reproduce.
How can I tell if I am infected with HIV?
The only way to know if you are infected with HIV is to be tested.
You cannot rely on symptoms to know whether you have HIV.
Many people who are infected with HIV do not have any symptoms at all for 10 years or more.
Some people who are infected with HIV report having flu-like symptoms (often described as
“the worst flu ever”) 2 to 4 weeks after exposure. Symptoms can include:
• fever
• enlarged lymph nodes
• sore throat
• rash
These symptoms can last anywhere from a few days to several weeks.
During this time, HIV infection may not show up on an HIV test, but people who have it are
highly infectious and can spread the infection to others.
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. Again, the only way to determine whether you
are infected is to be tested for HIV infection.
What are the stages of HIV?
A person can transmit HIV to others during any of these stages:
Acute infection:
• Occurs within 2 to 4 weeks after infection with HIV
• An individual may feel sick with flu-like symptoms (acute retroviral syndrome, ARS) or
primary HIV infection, and it’s the body’s natural response to the HIV infection. (Not
everyone develops ARS, however—and some people may have no symptoms.)
• Large amounts of HIV are being produced in the body. The virus uses important immune
system cells called CD4 cells (T-cells) to make copies of itself and destroys these cells in the
process. Because of this, the CD4 count can fall quickly.
• The ability to spread HIV is highest during this stage because the amount of virus in the
blood is very high.
• The immune response will begin to bring the amount of virus in your body back down to a
stable level. At this point, your CD4 count will then begin to increase, but it may not return to
pre-infection levels.
Clinical latency (inactivity or dormancy):
This period is sometimes called asymptomatic HIV infection or chronic HIV infection.
• HIV is still active, but reproduces at very low levels.
• An individual may not have any symptoms or get sick during this time.
• People who are on antiretroviral therapy (ART) may live with clinical latency for several
decades.
• For people who are not on ART, this period can last up to a decade, but some may progress
through this phase faster.
• It is important to remember that an individual is still able to transmit HIV to others during
this phase even if you are treated with ART, although ART greatly reduces the risk.
• Toward the middle and end of this period, the viral load begins to rise and the CD4 cell count
begins to drop. As this happens, an individual may begin to have symptoms of HIV infection
as their immune system becomes too weak to protect them.
AIDS (acquired immunodeficiency syndrome):
This is the stage of infection that occurs when your immune system is badly damaged and you
become vulnerable to infections and infection-related cancers called opportunistic illnesses.
• When the number of CD4 cells falls below 200 cells per cubic millimeter of blood (200
cells/mm3), an individual is considered to have progressed to AIDS. (Normal CD4 counts
are between 500 and 1,600 cells/mm3.)
• An individual can also be diagnosed with AIDS if they develop one or more opportunistic
illnesses, regardless of your CD4 count.
• Without treatment, people who are diagnosed with AIDS typically survive about 3 years.
• Once someone has a dangerous opportunistic illness, life expectancy without treatment falls
to about 1 year. People with AIDS need medical treatment to prevent death.
Common Opportunistic Infections
People with healthy immune systems can be exposed to certain viruses, bacteria, or parasites
and have no reaction to them—but people living with HIV/AIDS can face serious health
threats from what are known as “opportunistic” infections (OIs).
These infections are called “opportunistic” because they take advantage of your weakened
immune system, and they can cause devastating illnesses.
OIs are signs of a declining immune system. Most life-threatening OIs occur when your CD4
count is below 200 cells/mm3. OIs are the most common cause of death for people with
HIV/AIDS.
Some common OIs in HIV/AIDs patients are:
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Kaposis sarcoma
Pneumocystis carinii pneumonia
HIV dementia
HIV wasting syndrome
Superinfection
If someone already has HIV they can get another kind of HIV, this is called HIV superinfection.
Superinfection was first documented in 2002. It occurs when someone who is already infected
with HIV is exposed to different strain of HIV and becomes infected with that as well.
Two different strains of HIV can enter the same cell and bind their genetic material to become
what is known as a recombinant virus.
The effects of superinfection differ from person to person. For some people, superinfection may
cause them to get sicker faster because they become infected with a new strain of the virus that
is resistant to the medicines they are currently taking to treat their original HIV infection.
Research suggests that the kind of superinfection where a person becomes infected with a new
strain of HIV that is hard to treat is rare, less than 4%.