Acquired immune deficiency syndrome or acquired immunodeficiency syndrome (AIDS) is a disease of the human immune system caused by the human immunodeficiency virus (HIV).
This condition progressively reduces the effectiveness of the immune system and leaves individuals susceptible to opportunistic infections and tumors. HIV is transmitted through direct contact of a mucous membrane or the bloodstream with a bodily fluid containing HIV, such as blood, semen, vaginal fluid, preseminal fluid, and breast milk.
This transmission can involve anal, vaginal or oral sex, blood transfusion, contaminated hypodermic needles, exchange between mother and baby during pregnancy, childbirth, breastfeeding or other exposure to one of the above bodily fluids.
Genetic research indicates that HIV originated in west-central Africa during the late nineteenth or early twentieth century. AIDS was first recognized by the U.S. Centers for Disease Control and Prevention in 1981 and its cause, HIV, identified in the early 1980s.
Although treatments for AIDS and HIV can slow the course of the disease, there is currently no vaccine or cure. Antiretroviral treatment reduces both the mortality and the morbidity of HIV infection, but these drugs are expensive and routine access to antiretroviral medication is not available in all countries.
SYMPOTOMS
The symptoms of AIDS are primarily the result of conditions that do not normally develop in individuals with healthy immune systems. Most of these conditions are infections caused by bacteria, viruses, fungi and parasites that are normally controlled by the elements of the immune system that HIV damages.
Opportunistic infections are common in people with AIDS. HIV affects nearly every organ system.
People with AIDS also have an increased risk of developing various cancers such as Kaposi's sarcoma, cervical cancer and cancers of the immune system known as lymphomas. Additionally, people with AIDS often have systemic symptoms of infection like fevers, sweats (particularly at night), swollen glands, chills, weakness, and weight loss. The specific opportunistic infections that AIDS patients develop depend in part on the prevalence of these infections in the geographic area in which the patient lives.
CAUSES
Human immunodeficiency virus (HIV) causes AIDS. The virus attacks the immune system and leaves the body vulnerable to a variety of life-threatening infections and cancers.
HIV has been found in saliva, tears, nervous system tissue and spinal fluid, blood, semen (including pre-seminal fluid, which is the liquid that comes out prior to ejaculation), vaginal fluid, and breast milk. However, only blood, semen, vaginal secretions, and breast milk generally transmit infection to others.
The virus can be transmitted:
· Through sexual contact -- including oral, vaginal, and anal sex
· Through blood -- via blood transfusions or needle sharing
· From mother to child -- a pregnant woman can transmit the virus to her fetus through their shared blood circulation, or a nursing mother can transmit it to her baby in her milk
Other transmission methods are rare and include accidental needle injury, artificial insemination with infected donated semen, and organ transplantation with infected organs.
HIV infection is not spread by casual contact such as hugging, by touching items previously touched by a person infected with the virus, during participation in sports, or by mosquitoes.
It is not transmitted to a person who donates blood or organs. Those who donate organs are never in direct contact with those who receive them. Likewise, a person who donates blood is not in contact with the person receiving it. In all these procedures, sterile needles and instruments are used.
However, HIV can be transmitted to a person receiving blood or organs from an infected donor. To reduce this risk, blood banks and organ donor programs screen donors, blood, and tissues thoroughly.
AIDS begins with HIV infection. People infected with HIV may have no symptoms for 10 years or longer, but they can still transmit the infection to others during this symptom-free period. Meanwhile, if the infection is not detected and treated, the immune system gradually weakens, and AIDS develops.
Acute HIV infection progresses over time (usually a few weeks to months) to asymptomatic HIV infection (no symptoms) and then to early symptomatic (some symptoms) HIV infection. Later, it progresses to AIDS (very advanced HIV infection with T-cell count below 200).
Almost all people infected with HIV, if not treated, will develop AIDS. There is a small group of patients who develop AIDS very slowly, or never at all. These patients are called nonprogressors, and many seem to have a genetic difference that prevents the virus from damaging their immune system.
DIAGNOSIS
The diagnosis of AIDS in a person infected with HIV is based on the presence of certain signs or symptoms. Since June 5, 1981, many definitions have been developed for epidemiological surveillance such as the Bangui definition and the 1994 expanded World Health Organization AIDS case definition. However, clinical staging of patients was not an intended use for these systems as they are neither sensitive, nor specific. In developing countries, the World Health Organization staging system for HIV infection and disease, using clinical and laboratory data, is used and in developed countries, the Centers for Disease Control (CDC) Classification System is used.
TREATMENT
There is no cure for AIDS at this time. However, a variety of treatments are available that can help keep symptoms at bay and improve the quality of life of those who have already developed symptoms.
Antiretroviral therapy suppresses the replication of the HIV virus in the body. A combination of several antiretroviral agents, termed highly active antiretroviral therapy (HAART), has been highly effective in reducing the number of HIV particles in the blood stream, as measured by a blood test called the viral load. Preventing the virus from replicating can help the immune system recover from the HIV infection and improve T-cell counts.
HAART is not a cure for HIV, and people on HAART with suppressed levels of HIV can still transmit the virus to others through sex or sharing of needles. But HAART has been enormously effective for the past 10 years. There is good evidence that if the levels of HIV remain suppressed and the CD4 count remains high (above 200 cells/mL), life can be significantly prolonged and improved.
However, HIV may become resistant to HAART in patients who do not take their medications on schedule every day. Genetic tests are now available to determine whether a particular HIV strain is resistant to a particular drug. This information may be useful in determining the best drug combination for each individual, and adjusting the drug regimen if it starts to fail. These tests should be performed any time a treatment strategy begins to fail, and prior to starting therapy.
When HIV becomes resistant to HAART, other drug combinations must be used to try to suppress the resistant strain of HIV. There are a variety of new drugs coming out on the market for the treatment of drug-resistant HIV.
Treatment with HAART has complications. HAART is a collection of different medications, each with its own side effects. Some common side effects are nausea, headache, weakness, malaise (a general sick feeling), and fat accumulation on the back ("buffalo hump") and abdomen. When used for a long time, these medications increase the risk of heart attack by increasing the levels of fat and glucose in the blood.
Other antiviral medications are being investigated. In addition, growth factors that stimulate cell growth, such as Epogen (erthythropoetin) and G-CSF are sometimes used to treat anemia and low white blood cell counts associated with AIDS.
Medications are also used to prevent opportunistic infections (such as Pneumocystis uiroveci pneumonia) if the CD4 count is low enough. This keeps AIDS patients healthier for longer periods of time. Opportunistic infections are treated when they happen.
PREVENTTION
· Learn about safe sex and how to reduce the chance of acquiring or spreading HIV, and other sexually transmitted diseases.
· Try not to use injected drugs. If IV drugs are used, do not share needles or syringes. Many communities now have needle exchange programs, where you can get rid of used syringes and get new, sterile ones for free. These programs can also provide referrals to addiction treatment.
· Avoid contact with another person's blood. Protective clothing, masks, and goggles may be appropriate when caring for people who are injured.
· Anyone who tests positive for HIV can pass the disease to others and should not donate blood, plasma, body organs, or sperm. An infected person should tell any prospective sexual partner about their HIV-positive status. They should not exchange body fluids during sexual activity, and should use whatever preventive measures (such as condoms) will give the partner the most protection.
· HIV-positive women who wish to become pregnant should seek counseling about the risk to unborn children, and medical advances that may help prevent the fetus from becoming infected. Use of certain medications can dramatically reduce the chances that the baby will become infected during pregnancy.
· Mothers who are HIV-positive should not breast feed their babies.
· Safe-sex practices, such as latex condoms, are highly effective in preventing HIV transmission. However, there remains a risk of acquiring the infection even with the use of condoms. Abstinence is the only sure way to prevent sexual transmission of HIV.
