Causes and Diagnoses

Causes and Diagnoses of HIV

HIV can be transmitted from one infected person to another through blood, semen, vaginal secretions, rectal fluids and breast milk. Research has shown that HIV cannot be spread through saliva, sweat, tears, urine and feces.

HIV can be contracted any of these ways:

  • Unprotected sex of any kind
  • Sharing needles
  • At birth or through breastfeeding
  • Accidental blood contact

HIV transmission from blood transfusions rarely occurs in the United States. Also, HIV cannot be transmitted through casual contact, insect bites, pools or hot tubs, toilet seats, sharing glasses or utensils or kissing.

Preventing the spread of HIV

Take these steps to protect yourself and those you love from HIV infection:

  • Get tested. Know your HIV status and that of any sexual partner.
  • Practice safe sex. Use a condom or dental dam any time you have vaginal, anal or oral sex.
  • Get tested and treated for sexually transmitted diseases (STDs). Having an STD can increase your risk of contracting or spreading HIV.
  • Don’t inject drugs. Never share needles or use a used needle.
  • Take special precautions if you are pregnant. Talk to your physician about taking antiretroviral therapy (ART) and having your baby take ART. Use formula instead of breastfeeding.

Diagnosing HIV

The Centers for Disease Control recommends that everyone between the ages of 13 and 64 get tested for HIV at least once, as part of routine health care.

If you think you may have been exposed to HIV, it can take up to 6 to 12 weeks after exposure for the body to create antibodies that would show up in a test. While you can take tests a few weeks after exposure, it’s important to get retested three months after suspected exposure to confirm the results. In individuals with severely weakened immune systems due to chronic illness, it may take up to six months for antibodies to form, indicating the presence of HIV.

A diagnosis of AIDS is made when someone’s T cell (CD4) count has dropped below 200 per cubic millimeter of blood. In a healthy person, the T cell count is closer to 500 and 1,600 per cubic millimeter of blood. AIDS may also be diagnosed if someone has one or more opportunistic infections.

There are three main types of HIV tests:

  • Antibody test: This test measures antibodies to HIV in your blood or oral fluid. It can be performed at home or as a rapid results test at a clinic. A positive result requires a follow-up test.
  • Combination (fourth generation) test: This test looks for both antibodies and antigens (part of the virus).
  • Nucleic acid test: This test looks for the virus or viral load (concentration of the virus) itself in a blood sample. It is a costly option not generally used as a screening tool.
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