Groups And Subtypes Of Hiv
Genetic studies have led to a general classification system for HIV that is primarily based on the degree of similarity in viral gene sequence. The two major classes of HIV are HIV-1 and HIV-2. HIV-1 is divided into three groups, known as group M , group O , and group N . Worldwide, HIV-1 group M causes the majority of HIV infections, and it is further subdivided into subtypes A through K, which differ in expression of viral genes, virulence, and mechanisms of transmission. In addition, some subtypes combine with one another to create recombinant subtypes. HIV-1 group M subtype B is the virus that spread from Africa to Haiti and eventually to the United States. Pandemic forms of subtype B are found in North and South America, Europe, Japan, and Australia. Subtypes A, C, and D are found in sub-Saharan Africa, although subtypes A and C are also found in Asia and some other parts of the world. Most other subtypes of group M are generally located in specific regions of Africa, South America, or Central America.
In 2009 a new strain of HIV-1 was discovered in a woman from Cameroon. The virus was closely related to a strain of SIV found in wild gorillas. Researchers placed the new virus into its own group, HIV-1 group P, because it was unique from all other types of HIV-1. It was unclear whether the newly identified virus causes disease in humans.
Hiv/aids Is One Of The Worlds Most Fatal Infectious Disease
Almost 1 million people die from HIV/AIDS each year in some countries its the leading cause of death
HIV/AIDS is one of the worlds most fatal infectious diseases particularly across Sub-Saharan Africa, where the disease has had a massive impact on health outcomes and life expectancy in recent decades.
The Global Burden of Disease is a major global study on the causes of death and disease published in the medical journal The Lancet.1 These estimates of the annual number of deaths by cause are shown here. This chart is shown for the global total, but can be explored for any country or region using the change country toggle.
In the chart we see that, globally, it is the second most fatal infectious disease.
According to the Global Burden of Disease study, almost one million people died from HIV/AIDS in 2017. To put this into context: this was just over 50% higher than the number of deaths from malaria in 2017.
Its one of the largest killers globally but for some countries particularly across Sub-Saharan Africa, its the leading cause of death. If we look at the breakdown for South Africa, Botswana or Mozambique which you can do on the interactive chart we see that HIV/AIDS tops the list. For countries in Southern Sub-Saharan Africa, deaths from HIV/AIDS are more than 50% higher than deaths from heart disease, and more than twice that of cancer deaths.
Why Do Some People With Hiv Infection Develop Aids
Over time, untreated HIV infection damages the immune system and makes it more difficult to fight infections and cancers.
Before there were effective treatments for HIV infection, all infected people went on to develop AIDS within about 10 years. Today, people with HIV who take effective treatment are unlikely to develop AIDS and will have a near-normal life expectancy. This is because these medicines keep the amount of virus in their blood under control and protect the immune system.
Also Check: What Does An Hiv Blood Test Reveal
The Evolution Of Research And Treatment
In September 1985, President Ronald Reagan called AIDS research a top priority for his administration. This came amidst criticism that government funding was inadequate and not enough had been done to find a treatment or cure. This was Reagans first public statement about AIDS.
Zidovudine, commonly known as AZT, was introduced in 1987 as the first treatment for HIV. Scientists also developed treatments to reduce transmission during pregnancy.
In 1995, President Bill Clinton hosted the first White House Conference on HIV and AIDS, and called for a vaccine research center. This center later opened in 1999.
Throughout the years, the government has continued to fund HIV- and AIDS-related:
- systems of care
- studies and research
In 1996, in Vancouver, researchers at the 11th International Conference on AIDS introduced the concept of highly active antiretroviral therapy . This regimen requires people with HIV to take a combination of at least three medications daily. HAART, which is commonly known as antiretroviral therapy, became the new treatment standard in 1997.
Between 1996 and 1997, deaths from HIV in the United States, largely as a result of HAART.
Also in 1997, the FDA approved Combivir. Combivir combines the drugs zidovudine and lamivudine into a single medication, making HIV medications easier to take.
The FDA continues to approve HIV medical products, regulating:
- product approval
Where Did Hiv Come From
A zoonosis is an infection or infectious disease that is transmissible from vertebrate animals to people.
The best accepted theory about the origin of HIV is that it is a descendant of a closely related virus, simian immunodeficiency virus , which infects monkeys. Researchers have known for a long time that certain viruses can pass from animals to humans, a process that is called zoonosis. HIV may have crossed over from chimpanzees as a result of a human killing a chimp and eating it for food.
In 1999, researchers confirmed that tissue from a chimpanzee carried a form of SIV that was nearly identical to an aggressive form of HIV, HIV-1. It appears highly likely chimpanzees were the source of HIV-1, and that the virus at some point crossed species from chimpanzees to humans. We cannot say for sure when the virus first emerged, but it is clear that HIV started to infect humans and became epidemic in the middle of the twentieth century.
Why don’t mosquitoes transmit AIDS? The HIV virus does not multiply in mosquitoes. If a mosquito feeds on an HIV-infected human, the virus is treated like food and digested along with the blood meal. If the mosquito resumes feeding on a non-HIV-infected individual, too few particles are transferred to initiate a new infection.
Also Check: How Long Does Hiv Take To Turn Into Aids
Is There Only One Type Of Hiv
No, there are actually two types of HIV: HIV-1 and HIV-2, and they have slightly different origins.
HIV-1 is closely related to the strain of SIV found in chimps. While HIV-2 is closely related to the strain of SIV found in sooty mangabeys monkeys. The crossover of HIV-2 to humans is believed to have happened in a similar way as HIV-1 .
HIV-2 is far more rare, and less infectious than HIV-1, so it infects far fewer people. It is mainly found in a few West African countries, such as Mali, Mauritania, Nigeria and Sierra Leone.
To complicate things further, HIV is also classified by four main groups of viral strain , each of which has different genetic make-up. HIV-1 Group M is the strain that has caused the majority of HIV infections in the world today, meaning it is the dominant strain.
What Needs To Happen
The theme of this World AIDS Day Know Your Status is important. One in four people with HIV dont know that they have HIV. To bridge some critical gaps in the availability of HIV tests, WHO recommends the use of self-tests for HIV. WHO first recommended HIV self-testing in 2016, and now more than 50 countries have developed policies on self-testing. WHO, working with international organizations such as Unitaid and others, supported the largest HIV self-testing programmes in six countries in southern Africa. This programme is reaching people who have not tested themselves before, and is linking them to either treatment or prevention services. This World AIDS Day, WHO and the International Labour Organization will also announce new guidance to support companies and organizations to offer HIV self-tests in workplace. People with HIV often have other infections known as co-morbidities such as TB or hepatitis. One in three deaths in people with HIV is from TB. Around 5 million people are living with both HIV and viral hepatitis. One in three people with HIV has heart disease. This has meant that HIV care has long needed joined-up care, although this doesnt always happen in practice. WHO is now promoting person-centred health services to all people living with HIV, to meet their holistic health needs, not just their HIV infection linking HIV services with those for TB, sexual and reproductive health, non-communicable diseases and mental health, says Dr Hirnschall.
Recommended Reading: How Fast Does Hiv Spread In The Body
Where And When Did Hiv Start
Studies of some of the earliest known samples of HIV provide clues about when it first appeared in humans and how it evolved. The first verified case of HIV is from a blood sample taken in 1959 from a man who was living in what is now Kinshasa in the Democratic Republic of Congo.
Scientists used this sample to create a ‘family-tree’ of HIV transmission. By doing this, they were able to trace the first transmission of SIV to HIV in humans, which they concluded took place around 1920, also in Kinshasa. This area is known for having the most genetic diversity in HIV strains in the world, reflecting the number of different times SIV was passed to humans. Many of the first cases of AIDS were recorded there too.
Stigma As A Risk Factor
People with HIV are frequent targets of stigmanot just because of their HIV status, but sometimes also because of their sexual orientation and race. This can affect their health in a number of ways.
Some people wrongfully believe that the high rate of HIV among MSM confirms that gay and bisexual people are “promiscuous,””diseased,” or “immoral.” This attitude can send many MSM into hiding.
Testing positive may also force them to come out about how they got infected, which they may not want or be ready to do.
If they do get tested and have HIV, isolation and a lack of support can contribute to depression, alcohol or drug abuse, sexual risk-taking, and inconsistent treatment and care.
Many who begin medical treatment for HIV do not remain in care.
Also Check: How Long It Takes For Hiv To Be Detected
Stages Of Human Immunodeficiency Virus Infection
Stage I: Acute HIV infection
- A huge number of HIV is present in the blood, making the person contagious.
- The bodys natural response to infection is shown by flu-like symptoms.
- Only antigen or antibody tests or nucleic acid tests can diagnose acute infection.
Stage II: Chronic HIV infection
- Also called asymptomatic HIV infection or clinical latency that may last a decade or longer, but some may progress faster.
- HIV is active but reproduces at low levels.
- People remain asymptomatic during this phase though they can transmit HIV to others unknowingly.
- At the end of this phase, the amount of HIV in the blood goes up and the CD4 cell count goes down.
- Symptoms may begin as the person moves into stage III.
- People who have taken HIV medicine as prescribed may never move into stage III.
Stage III: Acquired immunodeficiency syndrome
- The last and most severe phase of HIV infection.
- People with AIDS have damaged immune systems, leading to severe illnesses called opportunistic infections.
- The diagnosis of AIDS is confirmed when the CD4 cell count drops below 200 cells/mm or the presence of certain opportunistic infections.
- A high viral load makes the person extremely infectious.
- If left untreated, the survival period is approximately three years.
Natural History Of Sivcpz Infection
Initially, SIVcpz was thought to be harmless for its natural host. This was because none of the few captive apes that were naturally SIVcpz infected suffered from overt immunodeficiency, although in retrospect this conclusion was based on the immunological and virological analyses of only a single naturally infected chimpanzee . In addition, SIV-infected sooty mangabeys and African green monkeys showed no sign of disease despite high viral loads in blood and lymphatic tissues , leading to the belief that all naturally occurring SIV infections are nonpathogenic. However, the sporadic prevalence of SIVcpz, along with its more recent monkey origin, suggested that its natural history might differ from that of other primate lentiviruses. To address this, a prospective study was initiated in Gombe National Park, Tanzania, the only field site where SIVcpz infected chimpanzees are habituated and so can be observed in their natural habitat.
Also Check: How To Be Safe From Hiv Aids
The Patient Zero Myth
For decades, a French-Canadian airline employee named Gaetan Dugas, has been known as Patient Zero in the 1980s AIDS epidemic.
Dugas, a man who had sex with men , died in 1984. Since then he has been blamed by some as a primary source for the spread of HIV in North America.
Dugas was one of the primary villains in the 1987 book, And the Band Played On, by San Francisco journalist Randy Shilts.
However, the researchers now say Dugas was falsely accused and unfairly blamed.
Gaetan Dugas is one of the most demonized patients in history, and one of a long line of individuals and groups vilified in the belief that they somehow fueled epidemics with malicious intent, said Richard McKay, D.Phil., a Wellcome Trust Research Fellow in Cambridges Department of History and Philosophy of Science, in a press release.
In fact, McKay says, Dugas actually provided scientists with valuable information before he died.
Dugas told researchers after he contracted HIV that he had 750 sexual partners the previous three years. That wasnt necessarily an unusual number. Researchers said 65 percent of men in a Los Angeles cluster study at the time reported having more than 1,000 sexual partners in their lifetimes.
Much of that sexual connection was with anonymous partners, so many HIV patients couldnt give medical officials any names.
However, McKay says, Dugas provided medical officials with 72 names. That helped scientists track down a wide range of people infected with HIV.
Where Did Aids Come From
Scientists have traced the origin of HIV back to chimpanzees and simian immunodeficiency virus , an HIV-like virus that attacks the immune system of monkeys and apes.
In 1999, researchers identified a strain of chimpanzee SIV called SIVcpz, which was nearly identical to HIV. Chimps, the scientist later discovered, hunt and eat two smaller species of monkeysred-capped mangabeys and greater spot-nosed monkeysthat carry and infect the chimps with two strains of SIV. These two strains likely combined to form SIVcpz, which can spread between chimpanzees and humans.
SIVcpz likely jumped to humans when hunters in Africa ate infected chimps, or the chimps infected blood got into the cuts or wounds of hunters. Researchers believe the first transmission of SIV to HIV in humans that then led to the global pandemic occurred in 1920 in Kinshasa, the capital and largest city in the Democratic Republic of Congo.
The virus spread may have spread from Kinshasa along infrastructure routes via migrants and the sex trade.
In the 1960s, HIV spread from Africa to Haiti and the Caribbean when Haitian professionals in the colonial Democratic Republic of Congo returned home. The virus then moved from the Caribbean to New York City around 1970 and then to San Francisco later in the decade.
International travel from the United States helped the virus spread across the rest of the globe.
READ MORE: Pandemics That Changed History: A Timeline
Recommended Reading: Can You Join The Army With Hiv 2022
How Do I Avoid Passing Hiv On To Someone Else
If you are infected with HIV, the best way to prevent spreading HIV infection to others is to:
- take your medication as prescribed there is a very low risk of passing on HIV if your own infection is under control
- use condoms and a water-based lubricant for anal and vaginal sex
- never share needles, syringes and other injecting equipment
If you have HIV infection, you are expected to notify anyone who is at risk of exposure from you:
- Tell people you have had sex or taken drugs with . Your doctor can help you decide who may be at risk and help you to contact them either personally or anonymously.
- Tell anyone you intend to have sex with about your HIV status . This is required by law in some states.
If you are pregnant, talk to your doctor about starting antiretroviral treatment to prevent the infection passing to the baby during pregnancy, childbirth or breastfeeding. Read more about HIV and pregnancy.
How Have Deaths From Hiv/aids Changed Over Time
Global deaths from HIV/AIDS halved within a decade
The world has made significant progress against HIV/AIDS. Global deaths from AIDS have halved over the past decade.
In the visualization we see the global number of deaths from HIV/AIDS in recent decades this is shown by age group. In the early 2000s 2004 to 2005 global deaths reached their peak at almost 2 million per year.
Driven mostly by the development and availability of antiretroviral therapy , global deaths have halved since then. In 2017, just under one million died from the disease.
You can explore this change for any country or region using the change country toggle on the interactive chart.
HIV/AIDS once accounted for more than 1-in-3 deaths in some countries, but rates are now falling
Global progress on HIV/AIDS has been driven by large improvements in countries which were most affected by the HIV epidemic.
Today the share of deaths remains high: more than 1-in-4 deaths in some countries are caused by HIV/AIDS. But in the past this share was even higher.In the visualization we see the change in the share of deaths from HIV/AIDS over time. From the 1990s through to the early 2000s, it was the cause of greater than 1-in-3 deaths in several countries. In Zimbabwe, it accounted for more than half of annual deaths in the late 1990s.
We see that over the past decade this share has fallen as antiretoviral treatment has become more widely available.
Children living with HIV
New HIV infections of children
You May Like: Will You Get Hiv If Your Partner Has It