EMERGENCE

The five cases of a rare type of pneumonia the June 1981 CDC MMWR reported were among homosexual men living in Los Angeles, California. The CDC was alerted to these cases when a seldom-used drug was suddenly being prescribed to treat this pneumonia. Subsequently, in July 1981, the CDC reported that 26 cases of Kaposi’s sarcoma (also a rare type of cancer) had been diagnosed within the previous 30 months. All of these cases of Kaposi’s sarcoma were also diagnosed among homosexual men. An overall increase of rare diseases indicated that a new virus was severely weakening patients’ immune systems and causing these rare diseases to emerge. Health authorities termed this emerging disease gay-related immune deficiency (GRID) because the initial cases were first seen among homosexual men.

In 1982, scientists determined that blood, and not homosexual activity, was the carrier of this new virus. Because blood had now been determined to be the carrier of GRID, the CDC warned blood banks about this new virus as blood recipients were at risk of contracting GRID. GRID was subsequently renamed AIDS because infection was not exclusive to homosexual activity.

In 1983 the French scientist Luc Montagnier discovered the virus that causes AIDS. An American scientist, Robert Gallo, also claimed to have discovered the existence of the virus. The resulting controversy was cleared up by attributing discovery of the virus to Luc Montagnier and confirmation to Robert Gallo. The virus was named HIV.

The first approved HIV test was developed and distributed in 1985 to test potentially infected people and blood supplies. Scientists, alerted to the possibly significant impact of HIV, created the International AIDS Conference to disseminate and discuss all aspects of HIV, including treatment, research, and prevention. The international community began to respond to the impact of HIV as the death toll rose exponentially.

The first anti-HIV drugs (Retrovir and Zidovudine) were approved by the Food and Drug Administration (FDA) in 1987. In the same year, President Ronald Reagan responded to this emerging epidemic as “public enemy number one” and the U.S. government banned the immigration of HIV-infected individuals. This ban is currently maintained; it holds that HIV is a disease of national significance. However, the U.S. attorney general may grant a waiver for HIV-infected individuals to enter for events (such as short-term visits and conferences). Other countries have various policies regarding the immigration of HIV-infected people into their countries.

Research continues to focus on HIV treatment for those who are infected as well as HIV vaccine development. New drugs have been developed to curb the progression of HIV to AIDS. Vaccine development has not been successful and scientists state that much research must still be done. They remain unsure whether an HIV vaccine will be found, and the HIV/AIDS epidemic continues to worsen.

DEFINITION AND PROGRESSION

AIDS is a disease in which HIV causes damage to the immune system and makes one susceptible to opportunistic infections and other illnesses. HIV, a retrovirus, is the cause of AIDS. HIV is a retrovirus because it stores its genetic information on a single-stranded RNA molecule instead of the usual double-stranded DNA molecule, and because after the retrovirus penetrates a cell, it uses a special enzyme to construct a DNA version of its genes which then becomes a part of the penetrated cell’s genetic material. HIV infects human cells and uses the cells’ nutrients and energy to reproduce and grow.

When a person is infected with HIV, the virus multiplies within the white blood cells, which are part of the immune system and normally protect the body from disease. The virus continues to replicate within the white blood cells and continues to damage other body cells. AIDS is diagnosed as HIV increases in prevalence in the body and causes increasing damage to the immune system. HIV causes the destruction of CD4 cells, a vital component of the immune system, and increases the number of opportunistic infections because the body is more susceptible to infections and cancers. Opportunistic infections occur in people who have compromised immune systems and are caused by various organisms. They are common among AIDS patients but are rarely seen in healthy people.

The CDC defines AIDS, for someone who has already tested as HIV seropositive, as meeting at least one of the following conditions:

• The presence of one or more AIDS-related infections or illnesses; and/or

• CD4 cell count has fallen below 200 cells per cubic millimeter of blood.

The period for progression from HIV to AIDS varies greatly and relies on several factors. These factors include the amount of time between the transmission of HIV and when the person is tested for HIV, the presence of antiretroviral therapy, and several other external factors such as access to care, the presence of other disease, and overall body health. Some people are co-diagnosed with HIV and AIDS and others are not diagnosed with AIDS for several years after they have been diagnosed with HIV. Some people do not develop symptoms for as long as 10 to 12 years. This long latency period (when the virus does not cause any significant symptoms) is problematic because people may not feel that they are sick and, therefore, do not feel the need to be tested for HIV.

TRANSMISSION

Someone who has been infected with HIV/AIDS carries the virus in certain body fluids, including blood, semen, vaginal fluids, and breast milk. Transmission of the virus can occur only when HIV-infected fluids enter the bloodstream of another person. HIV can enter the body through the vaginal lining, vulva, penis, rectum, mouth, or large cuts in the body. There have been no indications that HIV can be transmitted by saliva, tears, sweat, urine, feces, casual contact, or insects such as mosquitoes. There are three identified main transmission routes for HIV:

• Sexual transmission

• Blood or blood product

• Mother-to-child transmission

Sexual transmission of HIV occurs usually when an uninfected person has unprotected sex (anal, vaginal, or oral) with an HIV-positive person. Protected sex with an infected person is not 100 percent safe. Having protected sex involves the use of a condom that may break during sexual intercourse. Oral transmission of HIV is less likely, but can occur in such instances as when the uninfected person has open mouth sores or cuts that can be in direct contact with semen.

Direct contact with HIV-infected blood can occur when infected blood comes into contact with an uninfected person in a variety of ways. Transmission by blood can also occur when infected blood comes into contact with an open sore or cut. Blood transfusion was a cause of transmission before testing procedures were established. The United States screens all blood donations for HIV and, therefore, transmission by blood transfusion is highly unlikely in this country.

Transmission from an HIV-infected mother to her child during pregnancy or when breastfeeding is another possible HIV transmission route. Pregnant women who are HIV positive can transmit HIV to their unborn children during pregnancy. Pregnant woman who are not on HIV medication treatment transmit HIV to their newborn children in an estimated 20 to 30 percent of cases. HIV medication treatment is highly effective in preventing the transmission of HIV from mother to child during pregnancy, with the risk of transmission to the newborn reduced to 1 to 2 percent.

The most common ways that HIV is spread are by unprotected sex with an infected partner and/or sharing drug needles. There have been many theories regarding risky contact with bodily fluid; however, transmission not involving blood, semen, vaginal fluids, and breast milk have not been documented. Scientists state that if there were transmission routes (other than those mentioned above), then the epidemic would have looked very different and the numbers of those infected would have been much higher. The CDC investigates all cases that suggest a possible new transmission route.

SYMPTOMS/CLINICAL MANIFESTATIONS

The symptoms of HIV/AIDS vary greatly, depending on the patient’s stage of infection. When a person is initially infected with HIV, he or she may have no symptoms that are readily evident. However, within the first two to six weeks, the symptoms that usually occur are similar to when one has a flu-like illness. These symptoms include headache, fever, lethargy, and enlarged lymph nodes and they may last for one to two months. These symptoms are often overlooked by people because they are similar to other minor illnesses and, therefore, do not alarm the newly infected person.

During this initial period, people are highly contagious because genital fluids contain extremely high amounts of HIV. Because the genital fluids contain much higher amounts of HIV during this time, the likelihood or transmission increases greatly. After this initial period, the infected person may be asymptomatic (not showing any symptoms) for an extended time. The National Institutes of Health states that this period can sometimes last for as long as 10 to 12 years in some adults.

During this time, the virus continues to replicate and negatively affects the immune system. As the immune system declines, the symptoms become worse. The first signs of infection include enlarged lymph nodes, lethargy, weight loss, frequent fevers, persistent or frequent yeast infections, persistent skin rashes, pelvic inflammatory disease in women, short-term memory loss, herpes, genital or anal sores, and shingles (a painful nerve disease). The virus continues to attack the immune system and symptoms worsen and increase in prevalence. As the viral load increases, the HIV-infected person’s immune system deteriorates.

The symptoms that accompany the progression of HIV to AIDS include the following:

• coughing and shortness of breath

• seizures

• lack of coordination

• difficult or painful swallowing

• dementia (confusion and/or forgetfulness)

• severe diarrhea

• fever

• vision loss

• abdominal cramps, vomiting, nausea

• weight loss and extreme fatigue

• severe headaches

• coma

As an HIV-infected person’s condition worsens and they develop AIDS, they become more prone to developing diseases and cancers that are otherwise rarely seen in patients. Examples include Kaposi’s sarcoma and lymphomas (cancers of the immune system).

HIV TESTS

There are three types of tests that are used to detect HIV using blood or oral mucus samples. The tests are the antigen test, the antibody test, and the DNA or RNA test. Tests that detect the presence of HIV antibodies in the person’s bloodstream are the most commonly used. Antibodies are special proteins that are produced when HIV enters the bloodstream. HIV antibodies can be detected within six to 12 weeks from when HIV first enters the person’s bloodstream. In rare situations, it may take up to six months for a person to produce these antibodies.

The most widely used antibody test is called the enzyme-linked immunoabsorbant assay (ELISA). This test is highly sensitive, meaning that it is very accurate in detecting HIV antibodies but may not be as effective when distinguishing HIV antibodies from other antibodies. Consequently, if a person receives a positive ELISA test, it must be confirmed by another HIV test. In the United States, the Western blot assay test is used to confirm a positive ELISA test. The Western blot test is extremely accurate and detects the presence of HIV proteins. In resource-challenged countries, a second ELISA test is often used to confirm the first positive test result.

When discussing testing options, it must be noted that the HIV virus has a variable period between the point of infection (transmission) and the development of detectable antibodies. This means that there is a window of time during which the person is HIV positive and may be able to infect another person with HIV, but would test as HIV negative. The CDC states that this window of time can vary between three and six months.

Most countries have established protocols for HIV testing that involve counseling before and after receiving test results. A doctor, nurse, or certified counselor discusses the meaning of the test and test results with the patient. The amount of time it takes to receive the results depends on the type of test and varies between 30 minutes (HIV Rapid Test) and one week.

TREATMENT

At the beginning of the HIV epidemic, there were very few treatment options available. There were neither medications to treat the various types of opportunistic infections that arose nor medications adequate to bolster the immune system. Since the discovery of HIV, there have been several types of drugs developed to slow disease progression from HIV to AIDS and treat the accompanying opportunistic infections and cancers. No treatment exists to cure HIV/AIDS.

Current HIV/AIDS treatment consists of highly active antiretroviral therapy (HAART). HAART exists of combinations (known as cocktails) of at least three different types of HIV drugs belonging to at least two different classes of drugs. Each of these drugs interacts with the virus in different ways. The goal of these HIV medications is to decrease the viral load (the number of virus cells in the body of an infected person) and, consequently, keep the person healthier. The FDA has approved three groups of HIV drugs: nucleoside reverse transcriptase inhibitors, protease inhibitors, and fusion inhibitors.

Nucleoside reverse transcriptase inhibitors delay the spread of HIV by interrupting the early virus replication stage (when the virus is trying to make copies of itself) and delaying the onset of opportunistic infections. Protease inhibitors also interrupt the replication stage of the virus, but does so at a later stage during the process. Fusion inhibitors work by affecting HIV’s ability to enter into the white blood cell by blocking the merging of the virus with the cell membrane.

HAART has proven to be the most effective method to stabilize disease progression and has significantly decreased the impact of HIV. HAART medication adherence is extremely important because the virus can become resistant to HAART if it is not taken as prescribed and the medications will decrease in efficacy. Medication adherence has become an important global issue because as the viral strains become resistant to various HAART medications treatment becomes extremely difficult.

Post-exposure prophylaxis (PEP), consisting of anti-retroviral treatment, is available to reduce the risk of transmission if it is begun immediately after direct exposure. PEP consists of taking antiretroviral medications immediately following an exposure to HIV, within 72 hours of the exposure. This treatment must be taken for four weeks and consists of two to three different medications. PEP is used after occupational exposures (such as needle pricks) and, since 2005, PEP can be used when a person has had a risky sexual encounter (such as unprotected sex or having a condom break during intercourse).

SEXUALLY TRANSMITTED INFECTION(S) AND HIV/AIDS

It has been shown that having a sexually transmitted infection (STI) can increase the risk of acquiring HIV/AIDS. STIs can cause open sores or lesions in the skin to occur, thus increasing transmission likelihood. However, other biological events occur that also cause a person’s risk of acquisition to increase (such as tissue swelling). Studies have shown that people with an STI are more likely to contract HIV/AIDS. The risks associated with contracting certain STIs are very similar to those of HIV transmission.

EPIDEMIOLOGY

AIDS has been one of the most devastating epidemics recorded in history. UNAIDS and the WHO estimate that AIDS has killed more than 25 million people since it was first recognized in 1981. According to the 2006 UNAIDS Global Summary, there are currently 39.5 million people living with HIV/AIDS worldwide: 37.2 million adults, 17.7 million women, and 2.3 million children aged 15 years or younger. This same report states that in 2006, at least 4.3 million people were newly infected and at least 2.9 people died from AIDS.

Since 1981, great progress has been made to decrease the impact of HIV/AIDS. Developments include the identification of risk factors, development of HIV/AIDS testing and reporting standards, HIV/AIDS prevention and risk-reduction campaigns, HAART, and an increasing focus on access to medications. Researchers have also identified new risk (hot-spot) groups and trends. Currently, there is a worldwide growth of cases among women and young adults aged 15–24. Sub-Saharan Africa is the most affected region, accounting for 63 percent of people living with HIV/AIDS. Southern Africa is the most affected sub-Saharan region, accounting for 32 percent of the global estimation for those who are living with HIV/AIDS and 34 percent of all HIV/AIDS-related global deaths. The second most affected region is south and southeast Asia, with 8.6 million living with HIV/AIDS. Global rates of HIV infection have increased in all regions.

UNAIDS also states that many people do not know that they are infected with HIV/AIDS and, therefore, have not made behavioral modifications to prevent transmission. The CDC has estimated that one-fourth of infected peoples globally do not know that they are infected. The reason that people may not get tested for HIV includes lack of access to healthcare, stigmatization surrounding getting tested, and because they do not know that their behaviors cause them to be susceptible to HIV acquisition. This lack of testing also causes current HIV/AIDS prevalence and incidence (measuring the global burden of disease) to be inaccurate. Consequently, all statistics and estimates regarding HIV/AIDS are likely underestimates.

RISK POPULATIONS

HIV can be transmitted to anyone who is exposed to the virus and does not protect him- or herself properly. The CDC states that each year, more than 5 million people globally are infected with HIV. Many people are at risk for acquiring HIV, but some people are more susceptible due to their or their partner’s risk behavior(s). According to the CDC, the following populations are the most vulnerable to HIV infection:

• injection drug users

• drug and alcohol substance abusers

• commercial sex workers and their partners

• youth and street children

• prison populations

• men who have sex with men

These risk populations all have different characteristics associated with infection. These characteristics are often dependent on regional social and cultural characteristics, including (but not limited to) religious beliefs, stigmatization of healthy behaviors (such as condom use), disenfranchisement, and lack of education.

Some of these reasons are due to biological vulnerabilities. Women are more likely to contract HIV when having vaginal sex with an HIV-infected person than an uninfected man is when he is having vaginal sex with an HIV-infected woman. Apart from biological vulnerabilities, risk behaviors are what cause others to be vulnerable to contracting HIV. In the United States, HIV infection rates have remained alarmingly high among young people, minority groups (African Americans and Hispanics), and women. Cultural and social environments that influence one’s ability to avoid specific risk behaviors can exacerbate biological vulnerabilities. Much attention has been given to women and their ability to negotiate safer sex behaviors.

ECONOMIC IMPACT

The HIV/AIDS epidemic has affected life expectancy in certain hard-hit areas and, therefore, has negatively impacted labor force and human capital. The hardest-hit regions are also those areas with the least resources. In these areas, the population is affected by the cost of medical care, the inability to work due to medical condition, deaths, rising numbers of orphans, and an overall inability to cope with the impact of HIV/AIDS. As more people become infected, the labor force decreases.

Policy makers, public health officials, and HIV/AIDS scientists have pursued several goals to control and reduce HIV transmission rates. These goals include addressing social and cultural environment issues, increasing access to antiretroviral medications, increasing HIV/AIDS prevention and risk-reduction knowledge and practice, and increasing access to medical care. Scientists have been pushing global agendas that promote HIV testing as a means for controlling the spread of HIV. Increases in HIV testing will ensure that more people become aware of their HIV status and make behavioral changes, therefore limiting the spread of HIV. Testing will also increase the reliability of HIV/AIDS surveillance data.

SEE ALSO:

• AIDS and Infections; AIDS and Pregnancy; AIDS—Living with AIDS; AIDS-Related Malignancies; International AIDS Vaccine Initiative (IAVI); Joint United Nations Programme on HIV/AIDS (UNAIDS).