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#1 2023-06-07 00:10:25

Jai Ganesh
Administrator
Registered: 2005-06-28
Posts: 47,111

HIV

HIV

Gist

HIV (human immunodeficiency virus) is a virus that attacks the body's immune system. If HIV is not treated, it can lead to AIDS (acquired immunodeficiency syndrome). There is currently no effective cure. Once people get HIV, they have it for life. But with proper medical care, HIV can be controlled.

Summary

The human immunodeficiency viruses (HIV) are two species of Lentivirus (a subgroup of retrovirus) that infect humans. Over time, they cause acquired immunodeficiency syndrome (AIDS), a condition in which progressive failure of the immune system allows life-threatening opportunistic infections and cancers to thrive. Without treatment, average survival time after infection with HIV is estimated to be 9 to 11 years, depending on the HIV subtype.

In most cases, HIV is a sexually transmitted infection and occurs by contact with or transfer of blood, pre-ejaculate, semen, and vaginal fluids. Non-sexual transmission can occur from an infected mother to her infant during pregnancy, during childbirth by exposure to her blood or vaginal fluid, and through breast milk. Within these bodily fluids, HIV is present as both free virus particles and virus within infected immune cells. Research has shown (for both same-gender and opposite-gender couples) that HIV is untransmittable through condomless sexual intercourse if the HIV-positive partner has a consistently undetectable viral load.

HIV infects vital cells in the human immune system, such as helper T cells (specifically CD4+ T cells), macrophages, and dendritic cells. HIV infection leads to low levels of CD4+ T cells through a number of mechanisms, including pyroptosis of abortively infected T cells, apoptosis of uninfected bystander cells, direct viral killing of infected cells, and killing of infected CD4+ T cells by CD8+ cytotoxic lymphocytes that recognize infected cells. When CD4+ T cell numbers decline below a critical level, cell-mediated immunity is lost, and the body becomes progressively more susceptible to opportunistic infections, leading to the development of AIDS.

Details

Acquired immunodeficiency syndrome (AIDS) is a chronic, potentially life-threatening condition caused by the human immunodeficiency virus (HIV). By damaging your immune system, HIV interferes with your body's ability to fight infection and disease.

HIV is a sexually transmitted infection (STI). It can also be spread by contact with infected blood and from illicit injection drug use or sharing needles. It can also be spread from mother to child during pregnancy, childbirth or breastfeeding. Without medication, it may take years before HIV weakens your immune system to the point that you have AIDS.

There's no cure for HIV/AIDS, but medications can control the infection and prevent progression of the disease. Antiviral treatments for HIV have reduced AIDS deaths around the world, and international organizations are working to increase the availability of prevention measures and treatment in resource-poor countries.

Symptoms

The symptoms of HIV and AIDS vary, depending on the phase of infection.

Primary infection (Acute HIV)

Some people infected by HIV develop a flu-like illness within 2 to 4 weeks after the virus enters the body. This illness, known as primary (acute) HIV infection, may last for a few weeks.

Possible signs and symptoms include:

* Fever
* Headache
* Muscle aches and joint pain
* Rash
* Sore throat and painful mouth sores
* Swollen lymph glands, mainly on the neck
* Diarrhea
* Weight loss
* Cough
* Night sweats

These symptoms can be so mild that you might not even notice them. However, the amount of virus in your bloodstream (viral load) is quite high at this time. As a result, the infection spreads more easily during primary infection than during the next stage.

Clinical latent infection (Chronic HIV)

In this stage of infection, HIV is still present in the body and in white blood cells. However, many people may not have any symptoms or infections during this time.

This stage can last for many years if you're receiving antiretroviral therapy (ART). Some people develop more severe disease much sooner.

Symptomatic HIV infection

As the virus continues to multiply and destroy your immune cells — the cells in your body that help fight off germs — you may develop mild infections or chronic signs and symptoms such as:

* Fever
* Fatigue
* Swollen lymph nodes — often one of the first signs of HIV infection
* Diarrhea
* Weight loss
* Oral yeast infection (thrush)
* Shingles (herpes zoster)
* Pneumonia

Progression to AIDS

Access to better antiviral treatments has dramatically decreased deaths from AIDS worldwide, even in resource-poor countries. Thanks to these life-saving treatments, most people with HIV in the U.S. today don't develop AIDS. Untreated, HIV typically turns into AIDS in about 8 to 10 years.

When AIDS occurs, your immune system has been severely damaged. You'll be more likely to develop diseases that wouldn't usually cause illness in a person with a healthy immune system. These are called opportunistic infections or opportunistic cancers.

The signs and symptoms of some of these infections may include:

* Sweats
* Chills
* Recurring fever
* Chronic diarrhea
* Swollen lymph glands
* Persistent white spots or unusual lesions on your tongue or in your mouth
* Persistent, unexplained fatigue
* Weakness
* Weight loss
* Skin rashes or bumps

When to see a doctor

If you think you may have been infected with HIV or are at risk of contracting the virus, see a health care provider as soon as possible.

Additional Information

HIV, the human immunodeficiency virus, is the microorganism responsible for AIDS – acquired immunodeficiency syndrome. HIV gradually weakens the body’s immune system by infecting and destroying white blood cells called T-cells.

If left untreated, HIV causes AIDS – a life-threatening syndrome resulting from the immune system’s inability to defend itself from bacteria and other microorganisms. For those with access to it, HIV treatment called antiretroviral therapy can keep the virus in check and prevent AIDS. There is no cure for HIV, though some people who have had bone marrow transplants have had the levels of the virus reduced to undetectable levels, without the use of antiretroviral therapy.

History of HIV


The form of HIV that causes the vast majority of infections in humans is thought to have originated from a related chimpanzee virus called simian immunodeficiency virus, or SIV. Experts believe that SIV first crossed over to humans in what is now the Democratic Republic of Congo in the 1930s, where the world’s first known case of an HIV-related death was traced to a blood sample from a man who died in 1959.

The virus could have spread to humans who were hunting, butchering or consuming bush meat. There have been four independent transmission events from apes to humans, which have resulted in four different types of HIV, called strains. The most common strain, called HIV-1 group M, accounts for around 95 per cent of infections worldwide. HIV spread around the world, leading to a pandemic in the 1980s.

The 2008 Nobel Prize in physiology or medicine was awarded to the virologists, Françoise Barré-Sinoussi and Luc Montagnier, who discovered HIV in 1983. Their discovery of the virus led to the development of antiretroviral therapy, a combination of drugs that stop the virus from making more copies of itself and infecting new cells in the body.

According to World Health Organization figures, 32 million people have died globally because of HIV infection to date. This includes 770,000 people who died from HIV-related causes in 2018. Approximately 26 million of the 38 million people living with HIV today live in Africa.

HIV spread and prevention

HIV is spread through the exchange of bodily fluids, such as blood, semen and vaginal secretions, for example through gender or sharing intravenous needles. It can also be transmitted by a pregnant woman to her child during pregnancy, childbirth or breastfeeding. Interventions such as using condoms can prevent HIV from spreading from one person to another, as can screening people for HIV and providing them with treatment.

HIV treatment

The first antiretroviral drug, called AZT, was discovered in 1987. According to WHO figures, 13.6 million lives were saved due to antiretroviral therapy, between 2000 and 2018.

Studies suggest that people living with HIV who receive antiretroviral treatment have a similar life expectancy to the general population. When taken correctly, antiretroviral therapy can reduce HIV to undetectable levels in the blood, at which point the risk of spreading the virus becomes negligible. Treatment can prevent people who are HIV positive from transmitting the virus to their sexual partners, and pregnant women who are HIV positive from passing it to their babies. However in many parts of the world access to antiretroviral therapy is limited.

HIV cure?

HIV incorporates its DNA into the DNA of every cell it infects, meaning the virus cannot be completely eliminated from the body. Therefore antiretroviral therapy is not a cure, and people with HIV are advised to continue taking antiretroviral therapy to prevent the virus from making more copies of itself and infecting more cells.

Although there is no cure for HIV, several people have been “functionally cured” of the virus by receiving bone marrow transplants from people who are naturally resistant to HIV infection. HIV infects cells by attaching to a protein on their surface, called CCR5. Some people have a genetic mutation that changes the shape of this protein, meaning HIV can no longer attach to their cells, and these individuals are naturally resistant to infection.

In 2007, a HIV positive man in Berlin received a bone marrow transplant from a donor with the CCR5 mutation. This ‘Berlin patient’ remained HIV-free for the rest of his life. In 2019, a man known as the ‘London patient’ received a similar transplant and was also declared functionally cured of HIV. It’s thought that another individual, the ‘Düsseldorf patient’, may be the third person to be functionally cured of HIV.

Since the discovery of precise gene editing technologies like CRISPR, researchers have been investigating the possibility of ‘erasing’ HIV DNA from cells, as a potential cure strategy.

In 2018, in a world-first, Chinese researcher He Jiankui controversially used CRISPR on human embryos to introduce the CCR5 mutation and create babies who will be resistant to HIV infection. Following widespread criticism and ethical and safety concerns from the scientific community, his research programme has been stopped.

Development of a universal HIV vaccine has so far been unsuccessful, because of the ability of the virus to constantly mutate and change the way it appears to the body’s immune system.

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It appears to me that if one wants to make progress in mathematics, one should study the masters and not the pupils. - Niels Henrik Abel.

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