AIDS is a chronic, life-threatening condition caused by the human immunodeficiency virus (HIV). By damaging or destroying the cells of your immune system, HIV interferes with your body’s ability to effectively fight off viruses, bacteria and fungi that cause disease. This makes you more susceptible to certain types of cancers and to opportunistic infections your body would normally resist, such as pneumonia and meningitis. The virus and the infection itself are known as HIV. The term acquired immunodeficiency syndrome (AIDS) is used to mean the later stages of an HIV infection.

In the 25 years since the first reports of the disease, AIDS has become a global epidemic. Worldwide, an estimated 38.6 million people are living with HIV, nearly half of them women and girls between the ages of 15 and 24. And though the spread of the virus has slowed in some countries, it has escalated or remained steady in others. In 2005, more than 4 million people were newly infected with HIV; 25 million have died of AIDS since the epidemic began.

Despite improved treatments and better access to care for people in the hardest-hit parts of the world, most experts agree that the pandemic is still in the early stages. With a vaccine probably decades away, the best hope for stemming the spread of HIV now lies in prevention, treatment and education.

Signs and Symptoms

The symptoms of HIV and AIDS vary, depending on the phase of infection. When first infected with HIV, you may have no symptoms at all, although it’s more common to develop a brief flu-like illness two to six weeks after becoming infected. But because the signs and symptoms of an initial infection — which may include fever, headache, sore throat, swollen lymph glands and rash — are similar to those of other diseases, you might not realize you’ve been infected with HIV.

Even if you don’t have symptoms, you’re still able to transmit the virus to others. Once the virus enters your body, your own immune system also comes under attack. The virus multiplies in your lymph nodes and slowly begins to destroy your helper T cells (CD4 lymphocytes) — the white blood cells that coordinate your entire immune system.

You may remain symptom-free for eight or nine years or more. But as the virus continues to multiply and destroy immune cells, you may develop mild infections or chronic symptoms such as:

  • Swollen lymph nodes — often one of the first signs of HIV infection
  • Diarrhea
  • Weight loss
  • Fever
  • Cough and shortness of breath

During the last phase of HIV — which occurs approximately 10 or more years after the initial infection — more serious symptoms may begin to appear, and the infection may then meet the official definition of AIDS. In 1993, the Centers for Disease Control and Prevention (CDC) redefined AIDS to mean the presence of HIV infection as shown by a positive HIV-antibody test plus at least one of the following:

  • The development of an opportunistic infection — an infection that occurs when your immune system is impaired — such as Pneumocystis carinii pneumonia (PCP)
  • A CD4 lymphocyte count of 200 or less — a normal count ranges from 600 to 1,000

By the time AIDS develops, your immune system has been severely damaged, making you susceptible to opportunistic infections. The signs and symptoms of some of these infections may include:

  • Soaking night sweats
  • Shaking chills or fever higher than 100 F for several weeks
  • Dry cough and shortness of breath
  • Chronic diarrhea
  • Persistent white spots or unusual lesions on your tongue or in your mouth
  • Headaches
  • Blurred and distorted vision
  • Weight loss

You may also begin to experience signs and symptoms of later stage HIV infection itself, such as:

  • Persistent, unexplained fatigue
  • Soaking night sweats
  • Shaking chills or fever higher than 100 F for several weeks
  • Swelling of lymph nodes for more than three months
  • Chronic diarrhea
  • Persistent headaches

If you’re infected with HIV, you’re also more likely to develop certain cancers, especially Kaposi’s sarcoma, cervical cancer and lymphoma, although improved treatments have reduced the risk of these illnesses.

Symptoms of HIV in Children

Children who are HIV-positive often fail to gain weight or grow normally. As the disease progresses, they may have difficulty walking or delayed mental development. In addition to being susceptible to the same opportunistic infections that adults are, children may have severe forms of common childhood illnesses such as ear infections (otitis media), pneumonia and tonsillitis.

Causes

Normally, white blood cells and antibodies attack and destroy foreign organisms that enter your body. This response is coordinated by white blood cells known as CD4 lymphocytes. These lymphocytes are also the main targets of HIV, which attaches to the cells and then enters them. Once inside, the virus inserts its own genetic material into the lymphocytes and uses them to make copies of itself.

When the new copies of the virus break out of the host cells and enter the bloodstream, they search for other cells to attack. In the meantime, the old host cells and some uninfected CD4 cells die from the effects of the virus. The cycle repeats itself again and again. In the process, billions of new HIV particles are produced every day. Eventually, the number of CD4 cells in the body decreases, leading to severe immune deficiency, which means your body can no longer effectively fight off viruses and bacteria that cause disease.

How HIV is Transmitted

You can become infected with AIDS in several ways, including:

  • Sexual transmission. You may become infected if you have vaginal, anal or oral sex with an infected partner whose blood, semen or vaginal secretions enter your body. You can also become infected from shared sexual devices if they’re not washed or covered with a condom. The virus is present in the semen or vaginal secretions of someone who’s infected and enters your body through small tears that can develop in the rectum or vagina during sexual activity. If you already have another sexually transmitted disease, you’re at much greater risk of contracting HIV. Contrary to what researchers once believed, women who use the spermicide nonoxynol-9 also may be at increased risk. This spermicide irritates the lining of the vagina and may cause tears that allow the virus into the body.
  • Transmission through infected blood. In some cases, the virus may be transmitted through blood and blood products that you receive in blood transfusions. This includes whole blood, packed red cells, fresh-frozen plasma and platelets. In 1985, American hospitals and blood banks began screening the blood supply for HIV antibodies. This blood testing, along with improvements in donor screening and recruitment practices, has substantially reduced the risk of acquiring HIV through a transfusion.
  • Transmission through needle sharing. HIV is easily transmitted through needles and syringes contaminated with infected blood. Sharing intravenous drug paraphernalia puts you at high risk of HIV and other infectious diseases such as hepatitis. Your risk is greater if you inject drugs frequently or also engage in high-risk sexual behavior. Avoiding the use of injected drugs is the most reliable way to prevent infection. If that isn’t an option, you can reduce your risk by sterilizing injection paraphernalia with household bleach or by participating in a needle exchange program that allows you to trade used needles and syringes for sterile ones.
  • Transmission through accidental needle sticks. Transmission of the virus between HIV-positive people and health care workers through needle sticks is low. Experts put the risk at far less than 1 percent.
  • Transmission from mother to child. Each year, nearly 600,000 infants are infected with HIV, either during pregnancy or delivery or through breast-feeding. The rate of mother-to-child transmission in resource-poor countries is as much as 40 percent higher than it is in the developed world. But if women receive treatment for HIV infection during pregnancy, the risk to their babies is significantly reduced. Combinations of HIV drugs may reduce the risk of mother-to-child transmission even more. In the United States, most pregnant women are pre-screened for HIV, and anti-retroviral drugs are readily available. Not so in developing nations, where women seldom know their HIV status, and treatment is often limited or nonexistent. When medications aren’t available, Caesarean section is sometimes recommended instead of vaginal delivery, but this isn’t a good option for women in resource-poor countries, where it poses additional risks for both mother and child. Other options, such as vaginal disinfection, haven’t proved effective.
  • Other methods of transmission. In rare cases, the virus may be transmitted through organ or tissue transplants or unsterilized dental or surgical equipment.

Ways HIV is not transmitted
To become infected with HIV, infected blood, semen or vaginal secretions must enter your body. You can’t become infected through ordinary contact — hugging, dancing or shaking hands — with someone who has HIV or AIDS.

Risk Factors

HIV crosses all cultures, national borders and religions. Anyone of any age, race, sex or sexual orientation can be infected, but you’re at greatest risk of HIV/AIDS if you:

  • Have unprotected sex with multiple partners. You’re at risk whether you’re heterosexual, homosexual or bisexual. Unprotected sex means having sex without using a new latex or polyurethane condom every time.
  • Have unprotected sex with someone who is HIV-positive.
  • Have another sexually transmitted disease, such as syphilis, herpes, chlamydia, gonorrhea or bacterial vaginosis.
  • Share needles during intravenous drug use.
  • Have hemophilia and received blood products between 1977 and April 1985 — the date standard testing for HIV began.
  • Received a blood transfusion or blood products before 1985.
  • Have fewer copies of a gene called CCL3L1 that helps fight HIV infection.
  • Newborns or nursing infants whose mothers tested positive for HIV but did not receive treatment also are at high risk.

When to Seek Medical Advice

If you think you may have been infected with HIV or are at risk of contracting the virus, seek medical counseling as soon as possible. Tests are available that can determine your status. The idea of being tested for HIV infection is frightening for many people, yet a majority of Americans say they would support routine HIV testing for all adults. What’s more, testing itself doesn’t make you HIV-positive or HIV-negative and is important not only for your own health but also to prevent transmission of the virus to others.

You can be tested by your doctor or at a hospital, the public health department, a Planned Parenthood clinic or other public clinics. Many clinics don’t charge for HIV tests. Be sure to choose a place in which you feel comfortable and that offers counseling before and after testing. Don’t let concern about what people may think stop you from being tested. For a referral, or to make an appointment for an HIV test at a Planned Parenthood clinic near you, call 800-230-PLAN, or 800-230-7526. You can also contact your local or state health department.

If you’re pregnant, you may want to get tested even if you think you’re not at risk. If you are HIV-positive, treatment with anti-retroviral drugs during your pregnancy can greatly reduce the chances you’ll pass the infection to your baby. And if you engage in a high-risk behavior such as unprotected sex or sharing needles during intravenous drug use, experts recommend that you get tested for HIV every three to six months.

All states and U.S. territories now report positive HIV and AIDS test results to state public health officials to help track the spread of the disease. Most states use name reporting, but the results are released only to the health department and not to anyone else — including the federal government, employers, insurance companies and family members — without your express permission. In addition, legal provisions ensure the highest degree of confidentiality with regard to name-based HIV data. A few states, including Montana and Oregon, use name-to-code reporting. Don’t let the HIV reporting policy prevent you from seeking testing or treatment. If you are concerned about having your name reported, many states offer anonymous testing centers. If you do test positive and seek treatment, however, you will likely have to provide your name to your doctor.

Screening and Diagnosis

HIV is diagnosed by testing your blood or oral mucus for the presence of antibodies to the virus. The CDC encourages voluntary HIV testing as a routine part of medical care for all adolescents and adults ages 13 to 64, in new recommendations issued in September 2006. Although the CDC says that everyone should be tested at least once, yearly testing is recommended only for people at high risk of infection.
Unfortunately, HIV tests aren’t accurate immediately after infection because it takes time for your body to develop these antibodies — usually about 12 weeks. In rare cases, it can take up to six months for an HIV test to become positive.

For years, the only available test for HIV was the enzyme-linked immunosorbent assay (ELISA) test that looked for antibodies to the virus in a sample of your blood. If this test was positive — meaning you had antibodies to HIV — the same test was repeated. If the repeat test was also positive for HIV antibodies, you’d then have another confirming blood test called the Western blot test, which checks for the presence of HIV proteins. The Western blot test was important because you may have non-HIV antibodies that cause a false-positive result on the ELISA test. Combining the two types of tests helped ensure that the results were accurate, and you’d receive a diagnosis of HIV only if all three tests were positive.

The downside is that it can take up to two weeks to get the results of the ELISA and Western blot tests, a period of time that can take an emotional toll and that discouraged many people from returning to get their test results. Now, however, several “rapid” tests can give highly accurate information within as little as 20 minutes.

These tests look for antibodies to the virus using a sample of your blood or fluids collected on a treated pad that’s rubbed on your upper and lower gums. The oral test is almost as sensitive as the blood test and eliminates the need for drawing blood. A positive reaction on a rapid test requires a confirming blood test. And because the tests are relatively new and were originally approved for use only in certified laboratories, they may not be available in all locations.

Home Tests

A quick search of the Internet can turn up dozens of “do-it-yourself” HIV tests even though it’s illegal to market most of these tests in the United States. Currently, the Food and Drug Administration (FDA) has approved only one HIV test for home use. The Home Access HIV test, marketed by Home Access Health, is as accurate as a clinical test, and all positive results are automatically retested.

Unlike a home pregnancy test, you don’t perform the test yourself. Instead, you mail in a drop of your blood, then call a toll-free number to receive your results in three to seven business days. This approach ensures your privacy and anonymity — you’re identified only by a code number that comes with your kit. The greatest disadvantage is that you’re not offered the counseling that you typically receive in a clinic or doctor’s office, although you’re given referrals for medical and social services. No matter what type of test you choose, if you test positive for an HIV infection, tell your sexual partner or partners right away so that they can be screened and take steps to protect themselves.

If you receive a diagnosis of HIV/AIDS, your doctor will use a test to help predict the probable progression of your disease. This test measures the amount of virus in your blood (viral load). Studies have shown that people with higher viral loads generally fare more poorly than do those with a lower viral load. Viral load tests are also used to decide when to start and when to change your treatment.