The human immunodeficiency virus (HIV) is a retrovirus. A retrovirus is a type of virus that uses RNA (instead of DNA) for its genetic material. Retroviruses use a special enzyme to multiply, which allows them to change their RNA into DNA. The new DNA is then inserted into the DNA of the infected cell, which allows the virus to multiply every time the infected cell reproduces.
HIV infects a type of white blood cell called a helper T cell or CD4 cell. The virus can cause acquired immune deficiency syndrome (AIDS), a disease in which lymphocytes are destroyed and the body cannot protect itself from infections. Most cases of AIDS worldwide are the result of HIV infection.
Many people with HIV infection don’t get sick for many years. They are treated with anti-HIV drugs called highly active antiretroviral therapy (HAART). HAART controls the virus and allows the immune system to rebuild itself. However, as HIV disease progresses, it slowly wears down the immune system. As the immune system weakens, the person can develop AIDS.
People with HIV infection have a much higher risk of some types of cancer compared to people who are not infected.
HIV can spread from an infected person to someone else in the following ways:
- by having unprotected sex (oral, vaginal or anal)
- by sharing needles, syringes or other equipment for injecting drugs
- through a transfusion with contaminated blood or blood products
- Canadian Blood Services tests every blood donation for HIV. Only blood that does not contain this virus is used, so the risk of getting an HIV infection through a blood transfusion is very low.
- from an infected mother to a child during pregnancy, at birth or through breastfeeding
- if healthcare workers accidently get a needle stick or sharp equipment injury while caring for someone with HIV infection
- having an organ transplant from an HIV-infected person
- Organ donors are tested for HIV.
HIV is not spread by casual contact, such as talking, shaking hands, hugging, coughing or sneezing.
HIV infection and cancer
HIV does not appear to cause cancers directly. HIV infection weakens the immune system, so the body cannot fight infections and diseases as well. This can contribute to the development of cancer. Also, people infected with HIV may have a higher risk of some cancers compared with the general population in part because of the higher incidence of other risk factors, such as smoking, alcohol use and infection with other cancer-causing viruses like HHV8 and HPV.
There is sufficient evidence that HIV infection increases the risk of:
- Kaposi sarcoma
- anal cancer
- certain types of non-Hodgkin lymphoma
- Hodgkin lymphoma
- cervical cancer
- cancer of the conjunctiva (a thin membrane that lines the inner surface of the eyelids and the outer surface of the eye)
Other cancers may develop in people whose immune system is weakened because of HIV infection, including:
- some types of skin cancer
- reproductive cancers, such as vaginal, vulvar, penile and testicular cancer
- lung cancer
- liver cancer
- cancer of the mouth and throat
HAART has improved survival of people with HIV infection. HAART has also reduced the incidence of several diseases associated with HIV infection, including some types of cancer.
How to test for HIV
If you think you are at risk for HIV infection or have been exposed to HIV, talk to your healthcare provider about getting tested. A blood test is usually done to see if you have been exposed to the virus. People who have the HIV antibodies are said to be HIV-positive.
If you are pregnant and concerned about HIV, talk to your doctor about being tested. Early treatment with medication can prevent HIV from being spread from a mother to her baby before birth.
Reducing your risk
At this time, there is no vaccine that prevents HIV infection. To help reduce your risk for HIV infection:
- Practise safe sex.
- Use a condom to help protect against HIV infection, as well as other sexually transmitted infections.
- Do not share any needles, syringes or other drug use equipment.
- Do not share personal care articles, such as razors, scissors, nail clippers or toothbrush with an infected person.
- Wear latex gloves when you come into contact with someone else’s blood or body fluids.