The National Academies

The National Academies: What You Need To Know About Infectious Disease

What You Need To Know About Infectious Disease


HIV, or human immunodeficiency virus, is the virus that can lead AIDS, or acquired immune deficiency syndrome. HIV damages the immune system by destroying specific blood cells called CD4+ T cells, which are crucial to helping the body fight diseases. HIV is primarily transmitted by unprotected sex with an infected person. It can also be spread by sharing needles, syringes, and rinse water when preparing illicit drugs for injection and from mother to child during pregnancy, birth, or breastfeeding. Because HIV cannot reproduce outside the human body, it cannot spread through air, water, insects, saliva, tears, or sweat, nor can it be transmitted through casual contact, such as shaking hands, sharing dishes, or closed-mouth kissing.

AIDS is the late stage of HIV infection. The onset of AIDS means that the immune system has become severely damaged and has difficulty fighting diseases and certain cancers.

Within a few weeks of being infected with HIV, some people develop flu-like symptoms that last for a week or two but others have no symptoms at all. Although people living with HIV may appear and feel healthy for several years, HIV is still affecting their bodies. Untreated HIV infection is associated with many diseases, including cardiovascular disease, kidney disease, liver disease, and cancer.

There is no cure for HIV/AIDS. Many people with HIV, including those who feel healthy, can benefit greatly from medications used to treat HIV infection. The medications are called antiretroviral therapy (ART). These medications can limit or slow the destruction of the immune system, improve the health of people living with HIV, and possibly reduce the likelihood of transmitting HIV. In some cases, ART taken immediately after exposure can prevent infection, a phenomenon called post-exposure prophylaxis (PEP). But this treatment should only be used in emergency situations, within 72 hours of exposure. Individuals already infected and on a treatment regimen must be monitored carefully, and the medications must be taken daily, for life. The medications have potential side effects, such as nausea, vomiting, or diarrhea; heart disease; weakened bones or bone loss; abnormal cholesterol levels; and high blood sugar levels.

People at very high risk for HIV may consider pre-exposure prophylaxis (PrEP) to lower their chances of becoming infected. PrEP is a combination of two HIV medicines, tenofovir and emtricitabine, and is sold under the name TRUVADA®. It is approved for daily use as a preventive treatment. Knowing one’s HIV status can help prevent the spread of the disease in the population through sexual transmission. Limiting the number of sexual partners, abstaining from sex, or being in a long-term, mutually monogamous relationship with an uninfected partner are all effective ways to prevent the spread of HIV. Correct and consistent condom use can also reduce the risk of transmission. Drug users should ideally receive counseling and treatment to stop or reduce drug use but at a minimum they should use clean needles when injecting.


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What do you know about infectious disease?

True or False: The clearing and settlement of tropical rainforests has exposed woodcutters, farmers, and ecotourists to new vector-borne diseases.

  • Correct!

    The clearing and settlement of rainforests has exposed woodcutters, farmers, and ecotourists to new vector-borne diseases.

  • Sorry, that’s incorrect.

    The clearing and settlement of tropical rainforests has exposed woodcutters, farmers, and ecotourists to new vector-borne diseases.

Infectious Disease Defined


A branch of science that deals with the relation of organisms to one another and their physical environment.

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