The human immunodeficiency virus (HIV) is the virus that potentially causes AIDS (acquired immune deficiency syndrome). HIV primarily attacks the immune defense system, making the patient extremely vulnerable to opportunistic infections, which are infections that occur in people who have weakened immune systems.

HIV primarily infects and destroys immune cells with the CD4 receptor protein on their cell surfaces (also called CD4-positive or CD4+ T-cells). Healthy individuals have a CD4 cell count between 600 and 1,200 cells per microliter of blood. HIV patients have less than 600 CD4 cells per microliter of blood.

Patients progress to AIDS when/if their CD4 cell counts drop to lower than 200 cells per microliter (one-one millionth of a liter) of blood. This may happen if a person does not receive adequate treatment or if he/she develops a serious infection or illness. Individuals with a CD4 cell counts lower than 200 have the greatest risk of developing potentially fatal opportunistic infections, such as Mycobacterium avium complex (MAC) infections, because their immune systems are very weak.

HIV is transmitted from person to person via bodily fluids, including blood, semen, vaginal secretions, and breast milk. Therefore, it can be transmitted through sexual contact with an infected person, by sharing needles/syringes with someone who is infected, through breastfeeding, during vaginal birth, or, less commonly, through transfusions with infected blood. However, in countries where blood is screened for HIV antibodies, HIV infection is rarely transmitted through blood transfusions. Very low amounts of HIV have been found in saliva and tears in some AIDS patients. However, contact with saliva, tears, or sweat has not been shown to result in HIV transmission.

The most common type of HIV worldwide is called HIV-1. It is easily transmitted and is the cause of most HIV/AIDS infections around the world. HIV-1 has several subtypes (A through H and O), which are more common in certain parts of the world but produce AIDS similarly. The second type, called HIV-2, is much less common and less virulent or infectious.

Since 1981, when the first case of AIDS was reported in the United States, the disease has become a global pandemic, causing an estimated 65 million infections and 25 million deaths worldwide.

During the mid-to-late 1990s, advances in HIV treatment slowed the progression of HIV infection to AIDS. This consequently led to decreases in AIDS-related deaths. According to the U.S. Centers for Disease Control and Prevention (CDC), the number of AIDS-related deaths continues to decline, with an eight percent decrease from 2000 through 2004. However, the number of AIDS diagnoses increased eight percent during that period as well.

From 2000 to 2004, the estimated number of people living with AIDS increased from 320,177 to 415,193, according to the CDC. This 30% increase can partially be attributed to advanced treatments that have helped HIV/AIDS patients to live longer lives, as well as increased access to testing and information about the disease.

According to the CDC, an estimated 2.8 million patients died from AIDS, 4.1 million people became infected with HIV, and 38.6 million were living with HIV worldwide in 2005. According to the Joint United Nations Programme on HIV/AIDS (UNAIDS) and World Health Organization (WHO) 2006 AIDS Epidemic Update, an estimated 39.5 million people are currently living with HIV worldwide. It is also estimated that 4.3 million people became newly infected in 2006, with 2.8 million (65%) of these cases occurring in Sub-Saharan Africa. In 2006, 2.9 million people died from AIDS-related illnesses.

Certain geographic regions, such as Sub-Saharan Africa and the Caribbean, have much higher rates of infection than others. Certain populations, such as Sub-Saharan women, men who have sex with men (MSM), prostitutes, and injection-drug users, are also at increased risk for HIV infection.

Currently, there is no cure for HIV/AIDS. However, treatment with anti-HIV drugs, called antiretrovirals, may suppress the virus, which subsequently helps boost the immune system. Although these drugs may help patients live longer lives, they do not reduce the risk of transmitting the disease to someone else.

PATHOLOGY

General: HIV is transmitted from person to person via bodily fluids including blood, semen, vaginal secretions, and breast milk. Individuals who have other sexually transmitted diseases are more susceptible to the virus. This is because some STDs, such as syphilis, cause breaks in the skin or sores that make it easy for HIV to enter the body.

HIV is particularly difficult to treat because it reproduces very quickly and has a high mutation rate. When HIV reproduces, different strains (types) of the virus emerge. Mutations (changes in genetic information) occur almost every time a new copy of the virus is produced. Therefore, many types of HIV can be produced in a single person in one day. For this reason, HIV patients receive different combinations of antiretrovirals to suppress the virus.

HIV primary targets immune cells called CD4 T-cells. The CD4 T-cells are white blood cells that help coordinate the immune system's response to infection and disease. These cells have a molecule called CD4 on their surfaces, which allows the cells to detect foreign substances, including viruses that enter the body. This process then triggers the immune system to destroy the foreign substance. When HIV enters the body, the virus recognizes this protein, binds to the receptors on the CD4 cell wall, and enters the cell. Once inside the cell, HIV replicates and eventually kills the cell.

Primary, or acute, infection: Patients can transmit the virus to others during all stages of infection. The first stage of HIV, known as the primary or acute infection, is the most infectious stage of the disease, and it typically lasts several weeks. During this phase, the virus replicates rapidly, which leads to an abundance of the virus in the bloodstream and a drastic decline in the number of CD4 T-cells. The CD8 T-cells, which kill abnormal or infected body cells, are then activated to destroy HIV-infected body cells and antibodies are produced.

Clinical latency: The next stage, called clinical latency, may last anywhere from two weeks to 20 years. During this phase, HIV is not considered dormant. Instead, it is active in the lymph nodes where large amounts of the virus become trapped. The surrounding tissues, which contain high levels of CD4 T-cells, may also become infected. The virus accumulates in infected cells and in the blood as free virus. Patients generally do not experience symptoms during this stage until the CD4 cell count drops to 600 microliters of blood or lower.

Symptomatic stage: As the virus continues to weaken the immune system, patients eventually become more susceptible to infections. The next stage is the symptomatic stage, in which the person experiences symptoms associated with a weakened immune system.

AIDS: The term AIDS (acquired immune deficiency syndrome) refers to the most advanced stage of HIV infection. This stage happens when HIV multiplies rapidly and severely affects the immune system. Individuals have AIDS when they have fewer than 200 CD4 T-cells per microliter of blood. This low CD4 T-cell count makes them extremely vulnerable to potentially fatal opportunistic infections such as pneumonia or tuberculosis.

Several infections, including Pneumocystis jiroveci pneumonia (formerly called Pneumocystis carinii pneumonia, PCP) and Kaposi's sarcoma (KS), are considered AIDS-defining illnesses. This means that once a patient develops one of these infections, their condition has progressed to AIDS.

DEMOGRAPHICS

General: Race and ethnicity by themselves do not increase or decrease a person's risk of acquiring HIV infection. However, certain people are more likely to face challenges associated with the risk for HIV infection, such as lack of awareness of HIV status, substance abuse, or socioeconomic issues.

African Americans: In 2004, African Americans accounted for 20,965 (49%) of the 42,514 estimated AIDS cases (not HIV) diagnosed in the United States. The rate of AIDS diagnoses among African American adults and adolescents was 10 times higher than the rate of Caucasians and almost three times higher than the rate of Latinos. In addition, 23 times more African American women were diagnosed with AIDS than Caucasian women. Eight times more African American men were diagnosed with AIDS than Caucasian men, according to the CDC.

Latinos: In 2004, Latinos accounted for 20% (8,672) of the 42,514 new diagnoses in the United States, according to the CDC. The top causes of infection in most Latino men were infections after HIV exposure through sexual contact with other men, injection drug use, and heterosexual contact. The top causes of infection in Latino women were HIV exposure through heterosexual contact and injection drug use. Latinos were shown to get tested for HIV more often than any other race or ethnicity except African Americans. According to the CDC, in 2004, about 50% of Hispanics between the ages of 15 and 44 were tested, and 18% had been tested during the past year.

Women: After the initial outbreak of HIV, few women were diagnosed with the virus. Today, women account for more than 25% of all new HIV/AIDS diagnoses in the United States. In 2004, an estimated 93,566 women were living with AIDS, making up 23% of the estimated 415,193 people living with AIDS in the United States.

Youth (13-24 years old): In the United States, it is estimated that 50% of the 40,000 new HIV infections each year occur in people younger than age 25 and 25% of infections occur in people younger than 21. HIV/AIDS ranks as the sixth-leading cause of death among individuals ages 15-24 in the United States, with the number of AIDS cases reported each year in that age group increasing by 417% from 1981 through 1994.

Injection-drug users: Since the AIDS epidemic began, injection drug use (IDU) with illegal drugs has directly and indirectly (drug use clouds judgment, leading people to engage in high-risk behaviors) accounted for more than one-third of AIDS cases in the United States. In the year 2000, out of the 42,156 new cases of AIDS reported, 11,635 were linked to IDU.

Injection drug use is more common among racial and ethnic minorities in the United States, which makes them more likely to acquire HIV through IDU. In 2000, IDU accounted for 26% of all AIDS cases among African American adults and 31% among Hispanic adults and adolescents, compared to 19% of all cases among Caucasian adults and adolescents.

Homosexuals: Men who have sex with men (MSM) accounted for 70% of all estimated HIV infections among male adults and adolescents in 2004 in the United States, according to the CDC. Although the number of HIV diagnoses for MSM decreased during the 1980s and 1990s, the number increased by eight percent from 2003 through 2004. According to the CDC, it is unknown whether this increase is because more people are getting tested for HIV or because more patients are becoming infected with HIV.

Healthcare workers: Although healthcare workers are exposed to the virus at work, it is unlikely that they will acquire the virus from a patient, especially if they follow universal precautions, which should be taken with all patients.

For healthcare workers, HIV transmission is most likely to occur through accidental injuries from needles or other sharp medical instruments that may be contaminated with the virus. However, this risk is small. Researchers estimate that about 0.3-1% of healthcare workers exposed to the virus by an accidental needle stick or puncture develop HIV.

Since December 2001, there have been 57 documented reports of healthcare workers acquiring HIV from a patient. To prevent transmission of HIV to healthcare personnel in the workplace, the U.S. Centers for Disease Control and Prevention (CDC) offers precautionary guidelines.

TRANSMISSION

Bodily fluids: HIV is transmitted from person to person via bodily fluids because the virus is present in varying concentrations in the blood, semen, vaginal fluid, and breast milk. It can be spread by sexual contact with an infected person, by sharing needles/syringes with someone who is infected, or, less commonly, through transfusions with infected blood. HIV infection through blood transfusion is extremely rare in countries where blood is screened for HIV antibodies.

Environment: HIV does not survive well in the environment outside of the body. According to studies performed by the U.S. Centers for Disease Control and Prevention (CDC), drying HIV reduces the amount of viral particles by 90-99% within several hours. The virus also cannot reproduce when it is outside of the body. Therefore, it is highly unlikely that the disease can be transmitted through contact with the environment, such as public toilet seats.

Kissing: Casual contact through closed-mouth or "social" kissing does not put an individual at risk for HIV. However, there is the potential for blood contact with open-mouth kissing. The risk for acquiring the virus from open-mouth kissing is low, and the CDC has only investigated one case in which HIV transmission may have been caused by blood contact during open-mouth kissing. The CDC recommends that individuals avoid open-mouth kissing with an infected person.

Biting: There have been medical reports that found that HIV transmission resulted after a human bite. Severe trauma and extensive tissue tearing were reported in each of these cases. However, biting is not a common way of transmitting the disease.

Saliva, tears, and sweat: Very low amounts of HIV have been found in the saliva and tears of some AIDS patients. However, a small amount of HIV in body fluid does not necessarily mean that the fluid can transmit the virus. Contact with saliva, tears, or sweat has not been shown to result in transmission of HIV.

Insects: According to numerous studies, there is no evidence to suggest that HIV has been transmitted through insects, even in areas such as Africa, that have high numbers of AIDS patients and mosquito populations. HIV can only live for a short time inside an insect and does not reproduce inside insects.

Effectiveness of condoms: If a condom is used properly during sexual intercourse, an individual may reduce the risk of acquiring or transmitting STDs, including HIV. Several studies show that using condoms correctly and consistently may reduce the breakage rates of latex condoms to less than two percent.

There are many types and brands of condoms, but only latex or polyurethane condoms have been shown to effectively prevent HIV transmission when used appropriately. According to the CDC, natural membrane condoms, such as those made with lambskin, have natural pores that can possibly transmit diseases. Therefore, lambskin condoms are not considered to be effective in preventing HIV transmission.

Recent evidence has suggested that condom use by high-risk populations increases, rather than decreases the infection rate. According to the latest studies, condom promotion is only effective in lowering the rate of AIDS in concentrated, high-risk groups; condoms have never been shown to reduce HIV infection rates and AIDS deaths in general-population epidemics like those in sub-Saharan Africa. In on study, researchers asserted that of the three interventions scientifically shown to prevent AIDS - abstinence, being faithful, and using condoms - they argue that the use of condoms clearly comes last and should be promoted as a first-line defense only to those in extremely high-risk groups, such as commercial sex workers.

One prospective study showed that for 'receptive' men during anal sex, it made little or no difference whether their partners used a condom or not. Researchers suggested that condoms are less effective in anal sex than in vaginal sex.

SIGNS AND SYMPTOMS

Early symptoms: Many patients are asymptomatic (experience no symptoms) when they first become infected with HIV. After one or two months, an estimated 80-90% of HIV patients develops flu-like symptoms, including, headache, fever, fatigue, and enlarged lymph nodes. These symptoms usually last about one week to one month and are often mistaken for another viral infection, such as the flu. Despite having minimal or no symptoms during this stage, individuals are very infectious because the virus is present in large quantities in bodily fluids.

The most obvious sign of HIV infection is a decrease in the number of CD4 cells in the blood. These cells help fight against infection. HIV slowly kills these cells without causing symptoms. Even when the infected individual is asymptomatic, the virus is multiplying, infecting, and destroying cells in the immune system.

Clinical latency symptoms: After the initial infection with HIV, more serious symptoms develop. This next stage of infection is called clinical latency. Once infected with HIV, it may take 10 or more years for more severe symptoms to appear in adults or up to two years in children who are born with HIV infection. The length of this asymptomatic period varies among individuals. Some people may start to experience more serious symptoms within a few weeks, while others may have no symptoms for several years. The virus can also hide within infected cells. Patients can transmit the virus to others during all stages of the disease.

As the immune system continues to weaken, many symptoms appear, including inflamed lymph nodes (swollen glands) that may be enlarged for longer than three months. Other symptoms may include fatigue, weight loss, frequent fevers and sweats, persistent or frequent yeast infections (oral or vaginal), persistent skin rashes or flaky skin, pelvic inflammatory disease (PID) in women that does not respond well to treatment, and short-term memory loss.

In addition, some individuals develop a painful nerve disease called shingles or frequent and severe herpes infections that cause sores to develop on the mouth, genitals, or anus. Infected children may be sick often or grow slowly (failure to thrive) because their immune systems are still developing.

AIDS symptoms: Once the patient's CD4 T-cell count is less than 200 cells per microliter of blood, their condition has progressed to AIDS, the final stage of the disease. The first symptoms often include moderate and unexplained weight loss, frequent lung infections, and oral ulcerations (sores).

Patients are vulnerable to opportunistic infections and tumors. Opportunistic infections and tumors may include tuberculosis, thrush, herpes viruses, shingles, Epstein-Barr virus, pneumonia, and a type of cancer called Kaposi's sarcoma (KS). In the last stages of AIDS, it is common for individuals to have cytomegalovirus or Mycobacterium avium complex (MAC) infections.

COMPLICATIONS

Opportunistic infections:

General: Opportunistic infections are conditions that occur in individuals who have weakened immune systems. The organisms (bacteria, fungi, or viruses) that cause these infections do not cause illnesses in patients who have healthy immune systems because they are able to fight off the infection. The most common opportunistic infections associated with HIV and AIDS are Pneumocystis jiroveci pneumonia, Mycobacterium avium complex (MAC), toxoplasmosis, and tuberculosis. Patients at risk of developing these infections typically receive medication to prevent infections.

Pneumocystis jiroveci pneumonia: Pneumocystis jiroveci pneumonia (formerly called Pneumocystis carinii or PCP) is the most common opportunistic infection among HIV patients. Before antiretroviral therapy and preventative treatment was available, about 70-80% of people with HIV developed PCP. However, this number has been declining significantly over the years.

Originally, researchers thought a one-cell organism called Pneumocystis carinii caused the infection. However, recent research suggests that a fungus called Pneumocystis jiroveci is the cause. The condition is still commonly referred to as Pneumocystis carinii pneumonia (PCP).

According to the U.S. Centers for Disease Control and Prevention (CDC), PCP is classified as an AIDS-defining illness. This means that when HIV-infected patients develop PCP, their condition has progressed to AIDS. Individuals with a CD4 cell (helper T-cells that help fight against disease and infection) count lower than 200 cells per microliter of blood have the greatest risk of developing PCP. In addition, people who have CD4 cell counts lower than 300 who have already had another opportunistic infection have an increased risk of developing PCP.

This infection almost always affects the lungs causing a type of pneumonia. The first signs of PCP are difficulty breathing, fever, and a dry cough. Other common symptoms include chest discomfort, weight loss, chills, tachypnea (rapid breathing), tachycardia (fast heart rate), mild crackles (bubbling or rattling sounds that occur when air moves through fluid-filled airways), cyanosis (bluish discoloration of the skin), nasal flaring, and intercostal retractions (visible use of muscles between the ribs, which indicates labored breathing). The patient may also cough up blood, although this is considered a rare symptom.

Historically, mortality ranged from 20-40%, depending on the severity of the disease when it was diagnosed. Today, however, mortality rates range between 10-20%.

Today, PCP is almost entirely preventable, and it can be treated effectively with medications. Unfortunately, PCP is still common in patients who are infected with HIV for a long time before they begin antiretroviral therapy (ART). In fact, 30-40% of HIV patients develop PCP if they begin treatment when their CD4 cell counts are very low (around 50 cells per microliter of blood).

Mycobacterium avium complex (MAC): Mycobacterium avium complex (MAC), or mycobacterium avium intracellulare (MAI), is a bacterial infection that is caused by either Mycobacterium avium or Mycobacterium intracellulare. These bacteria are commonly found in water, soil, dust, and food. In fact, these bacteria are present in almost every human. However, a healthy immune system prevents the bacteria from causing an infection. HIV/AIDS patients are at risk of developing MAC.

According to the CDC, MAC is considered an AIDS-defining illness. It is estimated that up to 50% of individuals with HIV/AIDS develop MAC, especially if their CD4 count is lower than 50 cells per microliter of blood. MAC rarely causes infections in patients who have CD4 cell counts higher than 100 cells per microliter of blood.

MAC infections may be localized (limited to one part of the body) or disseminated (spread throughout the entire body, sometimes called DMAC). MAC infection often occurs in the lungs, intestines, bone marrow, liver, and spleen.

Common symptoms of MAC include weight loss, fever, chills, night sweats, swollen glands, abdominal pain, diarrhea, inflammation, and an overall feeling of weakness. MAC usually affects the intestines and inner organs first.

The most common complication of DMAC is anemia (low levels of red blood cells), which may require a blood transfusion. If the infection involves many organs, it may lead to respiratory failure and death. Patients who have localized infections that have not spread to other parts of the body have a low mortality rate because they are easier to treat.

Toxoplasmosis: Toxoplasmosis (toxo) is a parasitic infection that is caused by a single-celled parasite called Toxoplasma gondii.

Toxoplasma gondii is one of the most common parasites, found all over the world. Individuals may be exposed to the parasite in soil, cat feces, or in raw or undercooked meat (especially lamb, pork, or venison). There have also been rare reports of toxoplasmosis infection as a result of organ transplantation or blood transfusion.

It is estimated that more than 60 million Americans carry the parasite. However, 80-90% of infected patients are carriers (experience no symptoms) because the body's immune system prevents the parasite from causing illness. Toxoplasmosis is considered an AIDS-defining illness, according to the CDC.

HIV patients often experience symptoms such as headache, confusion, poor coordination, seizures, and ocular toxoplasmosis (severe inflammation of the retina) as well as lung problems that are similar to tuberculosis or pneumocystis pneumonia.

Tuberculosis: Tuberculosis (TB) is a bacterial infection of the lungs, which is caused by the bacterium Mycobacterium tuberculosis. Symptoms may include cough, shortness of breath, pleurisy (pain with breathing or coughing), fever, weight loss, night sweats, chills, and loss of appetite. The disease can cause serious breathing problems, which can be life threatening, especially if left untreated.

Tuberculosis is highly contagious. The disease is transmitted through airborne droplets when a person with the infection coughs, talks, or sneezes.

About 10-15 million Americans have latent TB infection, which means they are not sick, but they carry the bacterium that causes the disease. Only 10% of individuals with latent TB ever develop the infection.

While tuberculosis is not considered an AIDS-defining illness, HIV patients have an increased risk of developing TB because they have weakened immune systems. The risk of developing active TB increases 7-10% in HIV patients who have latent TB. HIV patients are more likely to experience symptoms in areas of the body other than the lungs. This is called extrapulmonary TB. The disease may affect the bones, joints, nervous system, or urinary tract. Also, TB appears to make HIV infection worse; researchers have observed faster HIV replication when tuberculosis is also present.

HIV and pregnancy:

Babies born to HIV-infected mothers may become infected during pregnancy, delivery, or breastfeeding. Therefore, the U.S. Centers for Disease Control and Prevention (CDC) recommend that all pregnant women get tested for HIV.

Antiretroviral therapy can significantly reduce the likelihood of an HIV-infected pregnant mother passing the virus to her baby. Patients who were taking antiretroviral medication before becoming pregnant should talk to their healthcare providers to determine the safest and most effective treatment option. In general, efavirenz (Sustiva©), stavudine (Zerit©), hydroxyurea (Droxia© or Hydrea©), and the oral liquid formulation of amprenavir (Agenerase©) should not be taken during pregnancy because they may cause harm to the fetus.

Because a baby may become infected though exposure to the mother's blood and vaginal secretions during delivery, the risk of infection increases with delivery time. Mothers with high levels of the virus in their blood might reduce their risk if they deliver their babies by cesarean section (surgical delivery of an infant), also called c-section. While c-sections may reduce the risk of transmission during birth, it is not typically necessary in patients taking antiretroviral therapy.

HIV infection rates of babies shortly before or after birth have been shown to drop to as low as 1-2% if their mothers take combination antiretroviral therapy during pregnancy, as well as zidovudine or nevirapine (Viramune©) preventative therapy during labor and after birth.

HIV-infected mothers should not breastfeed their babies because the virus may be transmitted via the breast milk. Instead, baby formulas should be used.

DIAGNOSIS

General: HIV is diagnosed after HIV antibodies or HIV itself is detected in the patient's body. As soon as the virus enters the body, the immune system produces antibodies, which are proteins that detect foreign substances in the body, including infectious agents like HIV. The presence of HIV antibodies in the blood, oral fluid, or urine can be used to determine whether HIV is in the body. Blood tests are the most commonly used HIV tests.

It may take some time for the immune system to produce enough antibodies for the antibody test to detect them. This time period, known as the "window period," varies among patients. Most people will develop detectable antibodies two to eight weeks after exposure, with the average being 25 days. However, some individuals might take longer to develop detectable antibodies. Of those infected with HIV, 97% develop antibodies within the first three months of infection. In very rare cases, it can take up to six months to develop antibodies to HIV. Therefore, if a patient tests negative for HIV in the first three months after possible exposure, repeat testing should be considered at least three months after the exposure.

In the United States, the test results must remain confidential. Individuals who are younger than 18 years old can consent to or refuse to be tested for HIV, without the involvement of their legal guardians. Test results may not be released to the patient's legal guardian(s) without his/her consent.

Who should get tested: The U.S. Centers for Disease Control (CDC) recommends that the following individuals get tested for HIV:

Individuals between the ages of 13 and 64 should be tested annually.

Individuals who have injected illegal drugs.

Individuals who have had unprotected vaginal, anal, or oral sex.

Individuals who have multiple or anonymous sexual partners.

Individuals who have exchanged sex for drugs or money.

Individuals who been diagnosed with or treated for hepatitis, tuberculosis (TB), or a sexually transmitted disease (STD), such as syphilis, gonorrhea, or chlamydia.

Individuals who have come in direct contact with an HIV-infected person's blood.

Individuals who have had unprotected sex with someone who meets any of the above stipulations.

Pregnant women should be screened for HIV as part of regular prenatal tests.

Pre-test counseling: According to the U.S. Centers for Disease Control and Prevention's (CDC) new guidelines for HIV testing, HIV prevention counseling is not required to accompany HIV screening. However, the CDC still recommends that patients receive information about HIV infection, transmission, and prevention. Patients should receive information about HIV testing and the meaning of test results. Healthcare providers should also tell the patient when to expect results and that confirmatory testing is necessary if the test result is positive. This is because it is possible for a false positive test result.

The patient may receive information through a pamphlet, brochure, video, or a one-on-one meeting with a certified counselor. Patients who are tested with a rapid HIV test should have equal access to the same types of information.

Prevention counseling: Prevention counseling is not mandatory, but it should be offered to all patients when they receive their test results. Counseling focuses on reducing the risks of HIV infection or transmission. The counselor makes a personalized detailed risk assessment of the patient. The counselor should also suggest behavior changes that may help reduce the patient's risk of developing or transmitting HIV. The counseling session is a chance to clear up any misconceptions or questions the patient may have about the disease.

Enzyme-linked immunosorbent assay (ELISA): The most common HIV tests use blood to detect HIV infection. The enzyme-linked immunosorbent assay (ELISA) tests a patient's blood sample for antibodies. Oral fluid (not saliva), collected from the cheeks and gums, may also be used to perform an ELISA. Oral fluid ELISA tests are considered as sensitive as a blood test. A urine sample may also be used during an ELISA, but this is considered less accurate than a blood or oral fluid test. A positive (reactive) ELISA for all samples must be used with a follow-up (confirmatory) test, such as the Western blot test, to make a positive diagnosis. Although false negative or false positive results are extremely rare, they may occur if the patient has not yet developed antibodies to HIV or if a mistake was made at the laboratory. When used in combination with the confirmatory Western blot test, ELISA tests are 99.9% accurate.

Western blot test: A Western blot test is typically used to confirm a positive HIV diagnosis. During the test, a small sample of blood is taken and it is used to detect HIV antibodies, not the HIV virus itself. The Western blot test separates the blood proteins and detects the specific proteins (called HIV antibodies) that indicate an HIV infection. The Western blot is used to confirm a positive ELISA, and the combined tests are 99.9% accurate.

Polymerase chain reaction (PCR): Polymerase chain reaction (PCR) tests are used to detect HIV's genetic material, called RNA. These tests can be used to screen the donated blood supply and to detect very early infections before antibodies have been developed. This test may be performed just days or weeks after exposure to HIV. Although these tests are the most accurate, they are not performed as often as the other HIV tests because they are expensive and also time- and labor-intensive.

Rapid test: A rapid test produces results in about 20 minutes. Rapid tests use a sample of blood or oral fluid to detect HIV antibodies. The patient's sample is placed on a test strip that contains HIV antigens. If the patient has developed HIV antibodies, the strip will change colors, indicating a positive result. A positive HIV test should be confirmed with a follow-up confirmatory test before a final HIV diagnosis can be made. These tests have similar accuracy rates as traditional ELISA screening tests.

Home-testing kit: Consumer-controlled test kits, also called home-testing kits, were first licensed in 1997. The Home Access HIV-1 Test System™ is a home kit that is approved by the U.S. Food and Drug Administration (FDA). The Home Access HIV-1 Test System™ is available at most local pharmacies. The individual pricks a finger with a special device and places drops of blood on a specially treated card. The card is then mailed to a licensed laboratory for testing. Home testing kits are confidential, and patients do not need to provide any personal information (such as name or address) when submitting samples. Instead, they call for results using a personal identification number (PIN). Callers may speak to a counselor any time before, during, or after the test. All individuals with positive test results are given referrals for follow-up confirmatory tests, as well as information and resources on treatment and support services. FDA-approved tests are equally as accurate as the tests performed in a doctor's office when performed correctly.

HIV drug resistance testing: Drug resistance testing is used to determine whether a patient with HIV has a mutated form of the virus that does not respond to antiretroviral therapy (ART).

If an HIV-infected patient becomes resistant to a drug and continues to take the same medication, HIV is able to multiply faster because the drug cannot stop it from replicating. When the new, mutated form is favored, it is called selective pressure. If the resistant virus makes enough copies of itself, it may eventually become the dominant type of HIV in the body. Once this happens, the medication is ineffective, and the patient will be resistant to the specific medication.

The FDA has approved the drug resistance test TrueGene™. The sensitivity, specificity, and reproducibility for many other tests have not been well established. However, several tests are available, and many health insurance plans cover them. There are two main types of drug resistance tests: genotypic and phenotypic resistance tests.

Genotypic resistance testing examines the genetic structure (genotype) of a patient's HIV. A blood sample is taken from the patient, and the HIV is analyzed for the presence of specific genetic mutations that are known to cause resistance to specific drugs. For instance, researchers have determined that lamivudine (Epivir©) and emtricitabine (Emtriva©) are not effective against forms of HIV that contain the mutation "M184V" in its reverse transcriptase gene. If a patient tests positive for this mutation, it is highly likely that he or she is resistant to both drugs, and different drugs should be prescribed.

Phenotypic testing directly measures the sensitivity (phenotype) of a patient's HIV in response to specific antiretrovirals. Many experts believe that these tests are more accurate and comprehensive than genotypic tests. These tests can help a physician determine the amount or concentration of a drug that is needed to stop a specific strain of HIV from replicating in a patient.

Genetic testing: Genetic testing can be done on several genes that affect HIV and the course of the infection. For example, a genetic mutation causing a protein defect called CCR5 delta 32 has been shown to be resistant to the HIV virus. Mutations in the major histocompatibility complex, class I, B (HLA-B) gene is also linked to the HIV virus. There are several variations in HLA-B that can either slow the progression of HIV to AIDS or speed it up. Mutations in the killer cell immunoglobulin-like receptor, three domains, long cytoplasmic tail, 1(KIR3DL1) gene and the chemokine (C-C motif) ligand 3-like 1 (CCL3L1) gene have also been associated with varying rates of AIDS progression.

TREATMENT

General: Although current antiretroviral drugs cannot cure HIV/AIDS, they may suppress the virus, even to undetectable levels. The guidelines for antiretroviral treatment are the same for adolescents and adults.

In emergency situations, or if parental involvement is impossible or could cause harm, and if the patient can adhere to treatment regimens, a minor can consent to treatment without parental involvement. However, communication with legal guardians should be encouraged in all patients who are younger than 18 years old and need to make healthcare decisions.

Patients who were taking antiretroviral medication before becoming pregnant should talk to their healthcare providers to determine the safest and most effective treatment options. In general, efavirenz (Sustiva©), stavudine (Zerit©), hydroxyurea (Droxia© or Hydrea©), and the oral liquid formulation of amprenavir (Agenerase©) should not be taken during pregnancy because they may cause harm to the fetus.

Highly active antiretroviral therapy (HAART): HIV patients typically receive a combination of antiretroviral drugs because a single patient may have several different strains (types) of the virus circulating in the blood. The different strains of the virus may respond differently to specific types of drugs. Therefore, highly active antiretroviral therapy (HAART), which is a combination of drugs from at least two different drug classes, is recommended. There are five major classes of antiretrovirals: fusion inhibitors, nucleoside/neucleotide reverse transcriptase inhibitors (NRTIs/NtRTIs), non-nucleoside reverse transcriptase inhibitors (NNRTIs), protease inhibitors, and integrase inhibitors. Each drug class disrupts different stages of HIV's life cycle.

Fusion inhibitors prevent the virus from entering and infecting human cells. The U.S. Food and Drug Administration (FDA) has approved the fusion inhibitor, enfuvirtide (Fuzeon©), also called T-20. Clinical trials have demonstrated that enfuvirtide-based therapy is an effective treatment for patients who have taken other types of antiretrovirals in the past. Enfuvirtide should not be taken in patients who have never received antiretroviral drugs before because it is only recommended when other drugs have not worked.

Nucleoside reverse transcriptase inhibitors (NRTIs) and nucleotide reverse transcriptase inhibitors (NtRTIs), also called nukes, inhibit HIV replication. HIV replicates by converting the viral RNA into complementary DNA (cDNA), which then integrates into the host DNA. A viral enzyme called reverse transcriptase (RT) converts the viral RNA into cDNA using host nucleotides, which are the building blocks of DNA. NRTIs are nucleoside analogs, or fake versions of nucleosides (which are the precursors to nucleotides), and the resulting DNA cannot be incorporated into the host DNA. NtRTIs are neucleotide analogs and do not need to be converted. Therefore, NtRTIs may have fewer side effects than NRTIs. The FDA has approved the following NRTIs: lamivudine/zidovudine (Combivir©), emtricitabine (Emtriva©), lamivudine (Epivir©), abacavir sulfate/lamivudine (Epzicom©), zalcitabine (Hivid©), zidovudine (Retrovir©), abacavir sulfate/lamivudine/zidovudine (Trizivir©), emtricitabine/tenofovir disoproxil fumarate (Truvada©), didanosine (Videx©, Videx EC©), stavudine (Zerit©), and abacavir sulfate (Ziagen©). Tenofovir disoproxil fumarate (Viread©) is an FDA-approved NtRTI.

Non-nucleoside reverse transcriptase inhibitors (NNRTIs), also called non-nucleoside analogs, interfere with viral replication. HIV replication requires the enzyme reverse transcriptase (RT), which is targeted by NNRTIs. When patients take non-nucleoside reverse transcriptase inhibitors (NNRTIs), the drug attaches to HIV's enzyme before it can use the patient's nucleic acid to multiply. NNRTIs significantly reduce the ability of HIV to multiply and infect new cells. The FDA has approved several NNRTIs, including delavirdine (Rescriptor©), efavirenz (Sustiva©), and nevirapine (Viramune©). Also, in July 2006, the FDA approved the multi-class combination drug efavirenz/emtricitabine/tenofovir disoproxil fumarate (Atripla©), which includes one NNRTI and two NRTIs.

Protease inhibitors (PIs) also interfere with HIV replication, they prevent the production of viral proteins that require an enzyme called protease. When protease is blocked, the new copies of HIV do not form properly and cannot infect new cells. The FDA has approved several protease inhibitors including: amprenavir (Agenerase©), tipranavir (Aptivus©), indinavir (Crixivan©), saquinavir mesylate (Invirase©), opinavir/ritonavir (Kaletra©), fosamprenavir calcium (Lexiva©), ritonavir (Norvir©), darunavir (Prezista©), atazanavir sulfate (Reyataz©), and nelfinavir mesylate (Viracept©).

In October 2007, the FDA approved an integrase inhibitor, called raltegravir (Isentress©), for the treatment of HIV in combination with other antiretrovirals. Integrase inhibitors are a new class of antiretrovirals that block the integrase enzyme that HIV uses to incorporate cDNA into host DNA.

Antiretroviral side effects: Individuals taking antiretroviral drugs often find it difficult to follow complicated drug plans. Current treatments involve taking at least two different classes of antiretroviral drugs daily. Also, some of the drugs may cause nausea or vomiting, some pills should be taken on an empty stomach, and others should be taken with food. Specific side effects depend on the specific drugs. In general, common side effects include changes in body fat distribution and blood lipid levels. Glucose metabolism (the breakdown of carbohydrates to produce energy) is also affected, which may lead to the onset or worsening of diabetes. It is estimated that about 2-10% of people taking antiretrovirals have diabetes.

The National Institute of Allergy and Infectious Diseases is among many research organizations that is investigating simpler, less toxic, and more effective drug plans.

Synergistic enhancers: Another group of medications, called synergistic enhancers, may also be used in combination with other antiretroviral drugs to treat HIV. These medications do not act as antiretrovirals when taken alone, but they have been shown to improve the antiretrovirals effects of other drugs, including ritonavir. Very small doses of synergistic enhancers may also be used to reduce the liver metabolism of other antiretroviral drugs.

Surgery: Patients infected with the human immunodeficiency virus (HIV) may require surgery to treat infections and diseases associated with the condition. With the introduction of HAART, HIV patients are able to live longer lives. As a result, it is possible that surgical interventions may be needed to diagnoses and/or treat long-term conditions. For example, lung infections, which may be caused by Pneumocystis jiroveci pneumonia (formerly called Pneumocystis carinii pneumonia, PCP), Mycobacterium avium complex (MAC), and tuberculosis often require invasive diagnostic procedures, such as bronchoalveolar lavage or an open lung biopsy. Like any surgical procedure, there are potential health risks. It remains unclear whether HIV patients are more likely to develop complications than HIV-negative patients.

Common complications of surgery include bleeding, infections, and nerve damage. It has been suggested that HIV patients may have an increased risk of surgical complications (especially infections) because they have weakened immune systems. However, there is currently no scientific data on the prevalence of surgical complications among HIV patients compared to non-infected patients.

Researchers believe that the risks of surgical complications for HIV patients can be predicted in a way similar to the method used in HIV-negative patients. Prior to surgery, healthcare providers should perform a physical examination, detailed medical history, and laboratory testing to determine the patient's overall health. Healthcare providers must also consider possible interactions between the patient's anti-HIV drugs (antiretrovirals) and medications, such as pain relievers, that are used before, during, and after surgical procedures.

It remains unclear whether a patient's CD4 cell count influences their risk of surgical complications. Healthy individuals have a CD4 cell count between 600 and 1,200 cells per microliter of blood. The lower the CD4 count, the weaker the patient's immune system. Some studies have found no correlation between low CD4 cell counts and surgical complications, while others have found an increase in complications with lower CD4 counts. Further research is needed before a firm conclusion can be made.

Organ transplants: As mentioned above, HAART enables HIV/AIDS patients to live longer lives. Today, most patients with HIV/AIDS are dying from end-stage organ disease and organ failure rather than AIDS-associated opportunistic infections. Since HAART prolongs the lives of HIV patients, it is possible for chronic conditions to progress to organ failure. For instance, HIV patients may experience end-stage liver disease as a complication of chronic hepatitis C virus. Glomeruli diseases are also common among HIV patients, and they may lead to kidney failure. In advanced stages of liver or kidney damage, organ transplants may be the patient's only chance of survival.

Until recently, people who had HIV were not considered good candidates for organ transplantations. Many patients were denied transplants under the assumption that they had shorter life expectancies and less favorable survival rates than other patients in need of transplants. However, now that patients are living longer lives, many groups are re-considering whether HIV patients should be transplant candidates.