Human Immunodeficiency Virus (HIV) Infection
What Happens
There are two types of HIV:
- HIV-1, which causes almost all the cases of AIDS worldwide.
- HIV-2, which causes an AIDS-like illness. HIV-2 infection is uncommon in Canada and the United States.
How the disease is spread
HIV is spread when blood, semen, or vaginal fluids from an infected person enter another person's body, usually through:
- Sexual contact. The virus may enter the body through a tear in the lining of the rectum, vagina, urethra, or mouth. Between 75% and 80% of all cases of HIV are transmitted by sexual contact.3, 4
- Infected blood. HIV can be spread when a person:
- Shares needles, syringes, cookers, cotton, cocaine spoons, or eyedroppers used for injecting drugs or steroids.
- Is accidentally stuck with a needle or other sharp item that is contaminated with HIV.
It is now extremely rare in Canada and the United States for HIV to be transmitted by blood transfusions or organ transplants. Blood and organ donors are screened for risk factors. All donated blood and organs are screened for HIV.
Health care workers are no longer considered to be at high risk of exposure to HIV. Policies are in place in health facilities that require protection from accidental exposure. Workers must properly dispose of sharp objects and wear protective gloves, gowns, and eye and face protection. These measures have been effective in protecting health care workers from HIV.
Spread of HIV to babies
A woman who is infected with HIV can spread the virus to her baby during pregnancy, delivery, or breast-feeding.
- Most children younger than 13 years who have HIV were infected with the virus by their mothers.
- The risk of a woman spreading HIV to her baby can be greatly reduced if she is on medicine that reduces her viral load (HIV RNA) to undetectable levels during pregnancy, if she receives zidovudine (ZDV) before the baby is born, and if she does not breast-feed her baby. The baby should also receive ZDV after it is born.
Ways HIV cannot be spread
HIV does not survive well outside the body. Therefore, HIV cannot be spread through casual contact—such as sharing drinking glasses or by casual kissing—with an infected person. HIV is not transmitted through contact with an infected person's saliva, sweat, tears, urine, or feces, or through insect bites.
Contagious and incubation period
The incubation period—the time between when a person is first infected with HIV and when early symptoms develop—may be a few days to several weeks.
It can take as little as 2 weeks or as long as 6 months from the time you become infected with HIV for the antibodies to be detected in your blood. This is commonly called the "window period," or seroconversion period. During the window period, you are contagious and can spread the virus to others. If you think you have been infected with HIV but you test negative for it, you should be tested again 6 months later.
After you become infected with HIV, your blood, semen, or vaginal fluids are always infectious, even if you receive treatment for the HIV infection.
Stages of HIV
Most people go through the following stages after being infected with HIV:
- Acute retroviral syndrome, which is a flu-like illness. This often develops within a few days of infection, but may occur several weeks after the person is infected.
- HIV without symptoms (asymptomatic). It may take years for HIV symptoms to develop. But even though no symptoms are present, the virus is multiplying (or making copies of itself) in the body during this time. HIV multiplies so quickly that the immune system cannot destroy the virus. After years of fighting HIV, the immune system starts to weaken.
- HIV with symptoms (symptomatic). After your immune system starts to weaken, you are more likely to develop certain infections or illnesses, such as some types of pneumonia or cancer that are more common in people who have a weakened immune system.
- AIDS, which occurs during the last stage of infection with HIV. If HIV goes untreated, AIDS develops in most people within 12 to 13 years after the initial infection. With treatment for HIV, the progression to AIDS may be delayed or prevented.
A small number of people who are infected with HIV are rapid progressors. They develop AIDS within about 3 years if they do not receive treatment. It is not known why the infection progresses faster in these people.
Non-progressors and HIV-resistant
A few people have HIV that does not progress to more severe symptoms or disease. They are referred to as non-progressors.
A small number of people never become infected with HIV despite years of exposure to the virus. For example, they may have repeated, unprotected sex with an infected person. These people are said to be HIV-resistant.
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| Author: | Douglas Dana Maria G. Essig, MS, ELS | Last Updated: October 10, 2007 |
| Medical Review: | Adam Husney, MD - Family Medicine Anne C. Poinier, MD - Internal Medicine W. David Colby IV, MSc, MD, FRCPC - Infectious Disease Peter Shalit, MD, PhD - Internal Medicine | |
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