Background
HIV/AIDS is one of the worst pandemics in human history, killing an estimated 25 million people since it was first recognized on December 1, 1981.
Since 1981, more than 980,000 cases of AIDS have been reported in the United States to the Centers for Disease Control and Prevention (CDC). According to CDC, more than 1,000,000 Americans may be infected with HIV, one-quarter of whom are unaware of their infection. The epidemic is growing most rapidly among minority populations and is a leading killer of African-American males ages 25 to 44. According, AIDS affects nearly seven times more African Americans and three times more Hispanics than whites. In recent years, an increasing number of African-American women and children are being affected by HIV/AIDS.
For global statistics, click here.
What is HIV/AIDS?
HIV stands for human immunodeficiency virus, a virus that causes AIDS, or acquired human immunodeficiency syndrome. HIV is different from most other viruses because it attacks the immune system, which gives our bodies the ability to fight infections. HIV finds and destroys a type of white blood cell (T cells or CD4 cells) that the immune system must have to fight disease.
The difference between HIV and AIDS
It is widely accepted that HIV causes AIDS. Untreated, the average time for an HIV-positive individual to develop AIDS is 10 years. AIDS is the final stage of HIV infection. It can take years for a person infected with HIV, even without treatment, to reach this stage. Having AIDS means that the virus has weakened the immune system to the point at which the body has a difficult time fighting infections. When someone has one or more of these infections and a low number of T cells, he or she has AIDS.
Origins of HIV
Scientists identified a type of chimpanzee in West Africa as the source of HIV infection in humans. The virus most likely jumped to humans when humans hunted these chimpanzees for meat and came into contact with their infected blood. Over several years, the virus slowly spread across Africa and later into other parts of the world.
How HIV causes AIDS
Untreated HIV disease is characterized by a gradual deterioration of immune function. Most notably, crucial immune cells called CD4 positive (CD4+) T cells are disabled and killed during the typical course of infection. These cells, sometimes called “T-helper cells,” play a central role in the immune response, signaling other cells in the immune system to perform their special functions.
A healthy, uninfected person usually has 800 to 1,200 CD4+ T cells per cubic millimeter (mm3) of blood. During untreated HIV infection, the number of these cells in a person’s blood progressively declines. When the CD4+ T cell count falls below 200/mm3, a person becomes particularly vulnerable to the opportunistic infections and cancers that typify AIDS, the end stage of HIV disease. People with AIDS often suffer infections of the lungs, intestinal tract, brain, eyes, and other organs, as well as debilitating weight loss, diarrhea, neurologic conditions, and cancers such as Kaposi’s sarcoma and certain types of lymphomas.
Most scientists think that HIV causes AIDS by directly inducing the death of CD4+ T cells or interfering with their normal function, and by triggering other events that weaken a person’s immune function. For example, the network of signaling molecules that normally regulates a person’s immune response is disrupted during HIV disease, impairing a person’s ability to fight other infections. The HIV-mediated destruction of the lymph nodes and related immunologic organs also plays a major role in causing the immunosuppression seen in people with AIDS. Immunosuppression by HIV is confirmed by the fact that medicines, which interfere with the HIV lifecycle, preserve CD4+ T cells and immune function as well as delay clinical illness.
Trasmission
HIV is spread most often through unprotected sex with an infected partner. The virus can enter the body through the lining of the vagina, vulva, penis, rectum, or mouth during sex.
Risky behavior
HIV can infect anyone who practices risky behaviors such as
- Sharing drug needles or syringes
- Having sexual contact, including oral sexual contact, with an infected person without using a condom
- Having sexual contact with someone whose HIV status is unknown
Infected blood
HIV also is spread through contact with infected blood. Before donated blood was screened for evidence of HIV infection and before heat-treating techniques to destroy HIV in blood products were introduced, HIV was transmitted through transfusions of contaminated blood or blood components. Today, because of blood screening and heat treatment, the risk of getting HIV from blood transfusions is extremely small.
Contaminated needles
HIV is often spread among injection drug users when they share needles or syringes contaminated with very small quantities of blood from someone infected with the virus.
It is rare for a patient to be the source of HIV transmitted to a healthcare provider or vice versa by accidental sticks with contaminated needles or other medical instruments.
Mother to child
Women can transmit HIV to their babies during pregnancy or birth. Approximately one-quarter to one-third of all untreated pregnant women infected with HIV will pass the infection to their babies. HIV also can be spread to babies through the breast milk of mothers infected with the virus. If the mother takes certain drugs during pregnancy, she can significantly reduce the chances that her baby will get infected with HIV. If healthcare providers treat HIV-infected pregnant women and deliver their babies by cesarean section, the chances of the baby being infected can be reduced to a rate of 1 percent. HIV infection of newborns has been almost eradicated in the United States because of appropriate treatment.
A study sponsored by the National Institute of Allergy and Infectious Diseases (NIAID) in Uganda found a highly effective and safe drug for preventing transmission of HIV from an infected mother to her newborn. Independent studies have also confirmed this finding. This regimen is more affordable and practical than any other examined to date. Results from the study show that a single oral dose of the antiretroviral drug nevirapine (NVP) given to an HIV-infected woman in labor and another to her baby within 3 days of birth reduces the transmission rate of HIV by half compared with a similar short course of AZT (azidothymidine).
Saliva
Although researchers have found HIV in the saliva of infected people, there is no evidence that the virus is spread by contact with saliva. Laboratory studies reveal that saliva has natural properties that limit the power of HIV to infect, and the amount of virus in saliva appears to be very low. Research studies of people infected with HIV have found no evidence that the virus is spread to others through saliva by kissing. The lining of the mouth, however, can be infected by HIV, and instances of HIV transmission through oral intercourse have been reported.
Scientists have found no evidence that HIV is spread through sweat, tears, urine, or feces.
Casual contact
Studies of families of HIV-infected people have shown clearly that HIV is not spread through casual contact such as the sharing of food utensils, towels and bedding, swimming pools, telephones, or toilet seats.
HIV is not spread by biting insects such as mosquitoes or bedbugs.
Sexually transmitted infections
People with a sexually transmitted infection, such as syphilis, genital herpes, chlamydia, gonorrhea, or bacterial vaginosis, may be more susceptible to getting HIV infection during sex with infected partners.
Symptoms
Early symptoms
Many people will not have any symptoms when they first become infected with HIV. They may, however, have a flu-like illness within a month or two after exposure to the virus. This illness may include
- Fever
- Headache
- Tiredness
- Enlarged lymph nodes (glands of the immune system easily felt in the neck and groin)
These symptoms usually disappear within a week to a month and are often mistaken for those of another viral infection. During this period, people are very infectious, and HIV is present in large quantities in genital fluids.
Later symptoms
More persistent or severe symptoms may not appear for 10 years or more after HIV first enters the body in adults, or within 2 years in children born with HIV infection. This period of asymptomatic infection varies greatly in each person. Some people may begin to have symptoms within a few months, while others may be symptom-free for more than 10 years.
Even during the asymptomatic period, the virus is actively multiplying, infecting, and killing cells of the immune system. The virus can also hide within infected cells and be inactive. The most obvious effect of HIV infection is a decline in the number of CD4 positive T (CD4+) cells found in the blood-the immune system’s key infection fighters. The virus slowly disables or destroys these cells without causing symptoms.
As the immune system becomes more debilitated, a variety of complications start to take over. For many people, the first signs of infection are large lymph nodes, or swollen glands that may be enlarged for more than 3 months. Other symptoms often experienced months to years before the onset of AIDS include
- Lack of energy
- Weight loss
- Frequent fevers and sweats
- Persistent or frequent yeast infections (oral or vaginal)
- Persistent skin rashes or flaky skin
- Pelvic inflammatory disease in women that does not respond to treatment
- Short-term memory loss
Some people develop frequent and severe herpes infections that cause mouth, genital, or anal sores, or a painful nerve disease called shingles. Children may grow slowly or get sick more frequently.
Youth (of color)
In the United States, youth of color are disproportionately hit the hardest. Racial and ethnic minority populations in the United States, primarily African Americans and Hispanics, constitute 58 percent of the more than 928,188 cases of AIDS reported to the Centers for Disease Control and Prevention (CDC) since the epidemic began in 1981. African Americans make up 50 percent of all AIDS cases reported in the United States, yet according to the U.S. Census Bureau, they comprise only 12 percent of the U.S. population. Hispanics represent 15 percent of all AIDS cases in the United States and are approximately 13 percent of the U.S. population.
Injection drug use is a major factor in the spread of HIV in minority communities. Other factors contributing to the spread of HIV/AIDS in these communities include men who have sex with men (MSM) and increasingly, heterosexual transmission.
According to CDC
- As of December 2003, African Americans and Hispanics represented 64 percent of males living with AIDS and 83 percent of those in females.
- As of December 2003, 67 percent of all women reported with AIDS are African American and 16 percent are Hispanic.
- African-American children represent almost 71 percent of all pediatric AIDS cases.
- Of the 59 pediatric AIDS cases reported in 2003, 40 were in African Americans and 7 were in Hispanics.
- AIDS is the leading cause of death among African-American men ages 25-44
Media
HIV Replication 3D Animation
HIV Drug Resistance 3D Animation
We have compiled basic information for you, ranging from the HIV myths to standard testing procedures.
Sources
Centers for Disease Control and Prevention
National Institutes of Health
