Hesperian Health Guides

What Are HIV and AIDS?

HIV (Human Immunodeficiency Virus) is a very small germ, called a virus, that you cannot see. AIDS (Acquired Immune Deficiency Syndrome) is a disease that develops later, after a person has been infected with HIV, the AIDS virus.


When a person becomes infected with HIV, the virus attacks the immune system, the part of your body that fights off infection. HIV slowly kills the cells of the immune system until the body can no longer defend itself against other infections. Most people who are infected do not get sick from their HIV for 5 to 10 years. But eventually the immune system cannot fight off common infections. Because HIV takes years to make someone sick, most people with HIV feel healthy and do not know they have it.

IMPORTANT! HIV can spread to others as soon as you are infected, even though you look and feel healthy. You cannot tell from looking at a person if he or she has HIV. The only way to know if you are infected is to get the HIV test.


A person has AIDS when the immune system gets so weak that it can no longer fight off infections. Often the signs are staying sick with several common illnesses, such as diarrhea or flu. The signs of AIDS may be different in different people. A person with AIDS may also get infections that are rare in people without HIV, like certain cancers or brain infections.

Good nutrition and the right medicines can help the person’s body fight infections caused by AIDS and allow her or him to live a long and healthy life. But there is no cure for HIV itself.

How HIV is Spread

HIV lives in certain body fluids of people infected with HIV—blood, semen, breast milk, and the fluids in the vagina. The virus is spread when these fluids get into the body of another person.
This means that HIV can be spread by:
unsafe sex with
someone who has
the virus. This is the
most common way
HIV spreads.
a man and woman lying together on a bed
unclean needles or syringes, or any tool that pierces or cuts the skin.
WWHND10 Ch17 Page 285-2.png
a woman in bed getting blood through a tube in her arm blood transfusions, if the blood has not been tested to be sure it is free from HIV
WWHND10 Ch17 Page 285-4.png
pregnancy, birth or breastfeeding, if the mother or father is infected
a person bandaging another person's bloody arm contact with infected blood if it gets into cuts or an open wound of another person

How HIV is NOT Spread

HIV does not live outside the human body for more than a few minutes. It cannot live on its own in the air or in water. This means you cannot give or get HIV in these ways:
WWHND10 Ch17 Page 285-6.png
WWHND10 Ch17 Page 285-7.png
WWHND10 Ch17 Page 285-8.png
by touching, kissing, or hugging by sharing food by sharing a bed
WWHND10 Ch17 Page 285 9.png
WWHND10 Ch17 Page 285-10.png
WWHND10 Ch17 Page 285-11.png
by sharing or washing clothes, towels, bed covers, latrines, or toilets, if you follow this advice. by caring for someone with HIV or AIDS, if you follow this advice. from insect bites

This page was updated:01 Feb 2021