International AIDS Society


Now 16344 members from 183 countries | 

Membership | Media | Abstract Archive | Online Resource Library                  IAS 2013 | AIDS 2014

IAS on twitter IAS on Facebook

HIV 101



Below is a list of some commonly asked questions in relation to HIV/AIDS. Clicking on any of the following questions will scroll down to the answer.

Frequently Asked Questions


Question: What is the origin of HIV?
Answer: The original source of HIV has been traced to a subspecies of chimpanzees native to west equatorial Africa, specifically southern Cameroon. It is believed that HIV-1 was introduced into the human population when hunters were exposed to infected blood.

For more information:
National Institutes of Health (NIH) News
CDC – Where did HIV come from?


Question: What were the first cases of HIV?
Answer: The earliest known case of HIV-1 in humans was collected in 1959 from a man in Kinshasa, Democratic Republic of Congo. A 1998 analysis of the 1959 plasma sample suggested that HIV-1 was introduced into humans in the 1940’s to 1950’s. There are some scientists who believe HIV-1 could date all the way back to the end of the 19th century.

For more infomation:
Avert.org – The Origins of HIV & The First Cases of AIDS
CDC – Where did HIV come from?


Question: Can you tell by looking at someone if they are infected with HIV?
Answer: No, it is impossible to look at someone and know their HIV status. An HIV- infected person may take years to develop any symptoms and can remain healthy even though the virus is actively replicating and spreading throughout the body. This is why it is especially important for a person who thinks he/she may have been exposed to HIV to get tested.

For more information:
www.aidshealth.org


Question: HIV vs. AIDS – What’s the difference?
Answer: Human Immunodeficiency Virus, better known as HIV, is a sexually transmitted virus that attacks the human body’s immune system. More specifically, HIV kills CD4 cells, or T-helper cells, that are essential for helping the body fight off infections. Acquired Immune Deficiency Syndrome (AIDS) occurs in the advanced stages of HIV infection. This is when the immune system can no longer fight infection and consequently the body is especially prone to life-threatening illnesses. It is important to note that a person can be infected with HIV, but not have AIDS. However, a person with AIDS must be infected with HIV.

For more information:
www.aidshealth.org
www.cdc.gov/hiv/
NIAID: How HIV causes AIDS


Question: What is the difference between HIV-1 and HIV-2?
Answer: Internationally, HIV-1 is the most prevalent type of the HIV virus. HIV-2 is not as common as HIV-1 and is typically concentrated in West Africa. Both types of HIV have the same modes of transmission and are associated with the some of the same opportunistic infections and AIDS. HIV-2 is less easily transmitted and often takes a longer time to progress. A person can be infected with both HIV-1 and HIV-2 at the same time.

For more information:
Avert.org – Introduction to HIV types, groups, and subtypes
CDC – Human Immunodeficiency Virus 2


Question: At what point is someone said to have AIDS?
Answer: A person is diagnosed with AIDS based on guidelines established by either the Centers for Disease Control (CDC) in developed countries or by the World Health Organization (WHO) in developing countries. According to the CDC, AIDS is defined as any HIV-positive person who has less than 200 CD4+ T-lymphocytes/μL, or a total lymphocyte percentage of less than 14%. CD4+ counts are used because as the amount of HIV virus increases in the body, the lower the CD4+ count is and the closer one is to AIDS. WHO proposed an interim clinical staging system in order to better define the progression of HIV to AIDS. The staging system is broken into 4 different stages. Once one stage is reached, an HIV-infected patient can only progress to a higher stage. Clinical Stage 4 indicates that the patient has progressed to AIDS. The four stages can be better understood in the tables below.


For more information:
WHO Disease Staging System for HIV Infection and Disease
1993 Revised Classification System for HIV Infection and Expanded Surveillance Case Definition for AIDS Among Adolescents and Adults


Question: What are CD4+ T-cells? Why are they used as the primary indicator of HIV progression?
Answer: CD4+ T-cells are a type of white blood cells that are vital for the immune system to function effectively. Their primary purpose is to fight off infections. They are used as the primary indicator for diagnosing AIDS because HIV attaches and infects these CD4+ cells, destroying billions of them daily. As these cells are destroyed, the immune system is weakened and unable to fight against HIV as well as other infections. A healthy human usually has between 500-1600 CD4+ cells/mm3 of blood or has a CD4+ cell percentage of between 20%-40% of all white blood cells. As HIV progresses, these numbers will significantly drop, causing a person to become much more vulnerable to other infections.

For more information:
The Body-The Complete HIV/AIDS Resource
Aidsmap.com


Question: How is HIV transmitted?
Answer: HIV is spread via sexual contact with an infected person, by sharing needles/syringes with someone who is infected, through transfusions of infected blood and blood produces, and from an infected mother to her baby before, during birth or through breast-feeding after birth. There have been accounts of infection by health-care workers who have been accidentally pricked with contaminated needles or open wounds. Heterosexual contact accounts for the highest percentage of infections. Everyone can be infected by HIV. There are no risk-groups, only risk behaviours that can increase one’s chance of infection.





For more information:
CDC – HIV and Its Transmission
Youandaids.org – The HIV/AIDS Portal for Asia Pacific


Question: How is HIV not transmitted?
Answer: There are many misconceptions about how HIV is transmitted. However, there is no scientific evidence that supports any of these claims. HIV is unable to replicate outside a living host and thus HIV transmission through air, water, or insects is highly improbable. Furthermore, there is no evidence that kissing, sneezing, coughing, holding hands or sharing cups with an HIV-infected person can transmit HIV. There is evidence that saliva and tears both contain HIV, but neither have a high enough viral load that would be necessary for it to be transmitted.

For more information:
avert.com – Can you get AIDS from…?
CDC – HIV and Its Transmission


Question: How does HIV reproduce in the body?
Answer: HIV is a retrovirus, meaning that it converts its single-stranded RNA genome into DNA during replication. Firstly, HIV attaches to the CD4 protein on the outside of a CD4+ cell, also known as a type of T-helper cell. Once it has entered the CD4 cell, HIV converts its viral RNA into DNA. This DNA is then integrated into the infected human’s DNA. Once HIV has infected a CD4+ cell, the cell can no longer fight off infections. Next, HIV is transcribed and translated by the host’s replication machinery to facilitate the production of new HIV proteins and enzymes. These new viruses exit the infected CD4+ cell to attack and infect other CD4+ cells. This is how HIV quickly spreads throughout the human body.

For more information:
avert.com – HIV structure and life cycle
Aidsinfonet.org – HIV Life Cycle
PBS.org – Surviving AIDS: See HIV in Action


Question: How can one determine if they have been infected with HIV?
Answer: Since a person is often asymptomatic when infected with HIV, their blood must be tested to determine if HIV antibodies are being produced. Antibodies are often produced within 6 weeks to 12 months after HIV infection and are the body’s natural response to fighting an infection. HIV infection can be determined by two different types of antibody tests: ELISA and Western Blot. Rapid HIV tests are also a type of HIV antibody test and produces results in less than 30 minutes.

For more information:
NIAID Fact Sheet
Aidsmap.com – HIV Antibody Testing


Question: Are there different types of HIV tests available?
Answer: There are 3 types of HIV testing: HIV antibody testing, HIV antigen testing, and PCR testing. HIV antibody testing is the easiest as well as the most common method of HIV testing. Antibody testing identifies antibodies being produced in response to an HIV infection. However, the body begins to make HIV antibodies only after approximately 6 weeks of infection. The period before antibodies are produced is called the window period and signifies the time in which HIV may not be detected by an antibody test. ELISA, Western Blots, and Rapid HIV tests are all types of HIV antibody tests. ELISAs are 99.5% accurate but can produce false positives which must be confirmed using another test such as western blots or immunoassays. Antigen tests detect any antigens (proteins found on the surface of the virus and trigger the body to produce antibodies) that are found in the blood. Antigen tests often have a shorter window period than antibody tests. However, once a person has antibodies, the antigen test will be negative. Since antigen tests have low sensitivity and are only accurate for a short period of time, they are used less frequently in the U.S. or the E.U. Lastly, PCR (Polymerase Chain Reaction) testing detects and extracts the HIV genome, if present. PCR has high sensitivity but is much more expensive than the other HIV tests because it requires technical skills and expensive machinery.

For more information:
Avert.org – HIV Testing
Thebody.com – The Complete HIV/AIDS Resource
National HIV Testing Resources
WebMD – Human Immunodeficiency Virus (HIV) Test


Question: How can one protect himself/herself from HIV transmission?
Answer: Prevention methods, behavioural interventions in particular, must be used in order to prevent HIV transmission. Reducing the number of risk-behaviours is an effective method that can greatly diminish the chance of contracting HIV. There are no ethnic groups or populations that are more at risk of getting HIV than others. Instead, there are populations that engage in particular behaviours that put them more at risk and having a higher probability of contracting HIV. Knowledge about safer sex behaviours is essential in order to reduce the transmission of HIV through sexual intercourse. Since sexual intercourse with an HIV positive partner the most common route of transmission throughout the world, condoms remain the most effective method to protect oneself from HIV.

For more information:
U.S. Food and Drug Administration (FDA)
Avert.org – HIV Prevention


Question: Are there other prevention methods currently being research and developed?
Answer: At present, researchers are working on new preventative strategies such as vaccines and other biomedical preventatives. Researchers have met many difficulties in the research and development of an effective HIV vaccine, but work continues in this field. See information on Vaccine Research. Microbicides and Pre-exposure Prophylaxis (PREP) are undergoing research and development as preventative strategies as well. The recent breakthrough on the success of male circumcision has also lead to an increase in circumcision research. Scientific research is crucial in order to learn more about the virus and produce methods of prevention. See also, Biomedical Prevention Research.

For more information:
avert.org – AIDS Vaccines and Microbicides
UNAIDS – Science and Research


Question: Is there a vaccine against HIV?
Answer: There is a great amount of interest focused on vaccine research and development; however, currently there are no HIV vaccines available.

For more information:
NIAID – HIV/AIDS Vaccines CDC – HIV/AIDS Research
International AIDS Vaccine Initiative
National Institutes of Health – Vaccine Research Center
U.S. Department of Health and Human Services – AIDS Info


Question: Is there a cure for AIDS?
Answer: Since the virus inserts its genome into human cells and then replicates, there is no cure for AIDS.

For more information:
avert.org – Cure for AIDS


Question: What types of treatment options are there?

Answer: HIV progresses differently in all people, yet all HIV-positive people will eventually need some form of treatment. Treatment usually begins when a person’s CD4 count drops below 200. HIV Antiretroviral Drugs are the main type of treatment to HIV. They aim at decreasing the replication of the virus in the human body. Most commonly, they come in the form of combination drugs (usually 3 drugs).The use of combination drugs decreases the chance of the virus becoming resistant to the drugs. The World Health Organization recommends the “twice-daily” combination of stavudine, lamivudine, and nevirapine. These three drugs are also available in one pill, making adherence to treatment easier.
For more information:
HIV Treatment Information
Avert.org – HIV/AIDS Treatment and Care
U.S. Department of Health and Human Services – AIDS Info
The Body: The Complete HIV/AIDS Resources: HIV Treatment
Positively Aware: 2006 HIV Drug Chart

Question: How many people are living with HIV/AIDS worldwide? How many of those are receiving treatment?
Answer: In 2007, 33.2 million people were estimated to be living with HIV/AIDS. The graph below shows the estimated amount of people living with AIDS every year since 1990. As of 2006, there was an estimated 2.015 million people living in low- and middle-income countries receiving anti-retroviral treatment out of the estimated 7.1 people in need. Below is a more detailed diagram.




For more information:
World Health Organization: Global HIV prevalence has levelled off
UNAIDS – 2007 AIDS Epidemic Update
UNAIDS: Towards Universal Access Progress Report
Avert.org- Who is getting AIDS drugs?


Question: What is Universal Access?
Answer: Universal Access states that everyone has an equal opportunity to access of HIV prevention, treatment, care, and support. In December 2005, The United Nations General Assembly requested that UNAIDS and its co-sponsors assist in “facilitating inclusive, country-driven processes, including consultations with relevant stakeholders, including non-governmental organization, civil society and the private sector, within existing national AIDS strategies, for scaling up HIV prevention, treatment, care and support with the aim of coming as close as possible to the goal of universal access to treatment by 2010 for all those who need it.”

For more information:
UNAIDS: Towards Universal Access
UNAIDS: Universal Access Issue Paper





HIV 101 | Basic Science | Treatment | Current Prevention Research | Advocacy Toolkits | Positive Living
Shortcuts: Contact IAS | Site Map | Contact Web master | Abstracts © 2013 International AIDS Society