Overview

HIV (human immunodeficiency virus) is a virus that attacks the immune system. When the virus enters your body, it targets and destroys a type of white blood cell called CD4+ T cells. These cells are responsible for triggering the immune system to fight infections. As the number of DC4+ T cells decreases, your immune system becomes weaker, making it harder for your body to fight off infections and diseases.

If left untreated, HIV infection can progress to AIDS (acquired immunodeficiency syndrome), which is the most severe form of HIV infection. AIDS is marked by the presence of opportunistic infections (infections that take advantage of a weakened immune system) or certain cancers.

HIV is transmitted through certain bodily fluids of an infected person, including blood, semen, vaginal fluid, breast milk, and rectal fluid. It’s not transmitted through casual contact such as shaking hands, hugging, and/or sharing meals or drinks.

While there is currently no cure for HIV, with early diagnosis and appropriate treatment, many individuals living with HIV can manage the virus and lead long, healthy lives.

Prevalence

HIV is a significant public health challenge, with an estimated 38 million individuals living with HIV globally as of 2020. While the prevalence of HIV varies by region, the virus is present in communities around the world and can affect anyone regardless of age, gender, sexual orientation, or race.

However, the number of new HIV infections has been declining globally over the past decade, with about 1.5 million new infections reported in 2019, down from a peak of 3.4 million in the mid-1990s.

Symptoms

In the early stages of an HIV infection, many individuals do not experience any symptoms or may only have flu-like symptoms that are often mistaken for other illnesses.

As the virus progresses, however, it can cause a wide range of symptoms, which may include the following:

• Fever
• Fatigue
• Night sweats
• Rapid weight loss
• Chronic diarrhea
• Swollen lymph nodes
• Skin rashes or sores
• Mouth or genital ulcers
• Persistent dry cough
• Shortness of breath
• Recurring fever, chills, or night sweats
• Cognitive or neurological symptoms, including confusion, memory loss, and/or depression

These symptoms can also be caused by other illnesses or conditions, and having one or more of these symptoms does not necessarily mean that an individual has HIV. The only way to confirm a diagnosis of HIV is through testing.

Some people with HIV may be asymptomatic for many years, while the virus is still damaging their immune system. This is why regular HIV testing is recommended for individuals who are at risk of infection. Early diagnosis and treatment can improve your outcomes and reduce the risk of transmission to others.

Stages

The HIV infection typically progresses through 3 stages, each of which is characterized by different levels of virus in your body, different symptoms, and different health outcomes if left untreated.

1. Acute HIV infection

   This is the initial stage of HIV infection, which occurs within 2–4 weeks of exposure to the virus. During this stage, the virus rapidly replicates in your body, leading to a surge in viral load (the amount of virus in your blood).

   Symptoms may include fever, fatigue, sore throat, rash, and swollen lymph nodes. Some may not experience any symptoms at all.

   Without appropriate treatment, the acute stage of HIV infection typically resolves within a few weeks, after which the virus enters a latent (or dormant) phase.

2. Chronic HIV infection

   This stage of HIV infection may last for several years, during which the virus continues to replicate in your body, but at a slower rate than during acute infection.

   While symptoms may be mild or absent, individuals in this stage may experience some immune system damage and an increased risk of opportunistic infections and cancers.

   Regular HIV testing is important to monitor the progression of the infection and initiate treatment if necessary.

3. AIDS (Acquired Immunodeficiency Syndrome)

   This is the most advanced stage of HIV infection, which typically develops in individuals who have not received appropriate treatment for the virus.

   AIDS is characterized by a very low CD4+ T cell count—less than 200 cells per cubic millimeter of blood (normal range between 500 and 1500) and/or the development of certain opportunistic infections or cancers that are typically associated with advanced HIV infection. These infections and cancers can be severe and even life-threatening.

Transmission

Certain bodily fluids from an infected person can transmit HIV. These fluids include:

• blood
• semen
• pre-seminal fluids
• rectal fluids
• vaginal fluids
• breast milk

For transmission to occur these fluids must come in contact with a mucous membrane or damaged tissue or be directly injected into the bloodstream (from a needle or syringe).

• Unprotected sexual contact: Transmission can occur when a condom is not used or used incorrectly through vaginal, anal, and/or oral sex with an infected partner.
• Sharing needles and syringes: Used needles and syringes may have infected person's blood on them.
• From mother to child: Transmission can occure during pregnancy, childbirth, and/or breastfeeding.

Less common causes of HIV transmission may include blood transfusion or organ transplantation from an infected donor (although this is rare in countries with established blood and organ screening programs), and occupational exposure to HIV-infected blood, such as through accidental needle sticks in healthcare settings.

Other factors that increase the risk of exposure to HIV include having multiple sexual partners and STIs (sexually transmitted infections) such as syphilis, herpes, and gonorrhea.

Complications

HIV can lead to a range of complications, particularly if left untreated or not managed effectively. Some of the potential complications of HIV may include the following:

• Opportunistic infections

  Individuals with HIV are more susceptible to opportunistic infections, which are infections that take advantage of a weakened immune system. Some examples include tuberculosis, pneumonia, and certain types of cancer.

• AIDS

  If HIV is left untreated, it can progress to AIDS (acquired immunodeficiency syndrome), which is a more advanced stage of HIV infection. Individuals with AIDS have significantly weakened immune systems, making them more susceptible to opportunistic infections and other complications.

• Neurological complications

  HIV can affect the nervous system and lead to a range of neurological complications, such as dementia, neuropathy, and meningitis.

• Cardiovascular disease

  Individuals with HIV are at increased risk of cardiovascular disease, such as heart attacks and stroke.

• Kidney disease

  HIV can lead to kidney damage and kidney disease, particularly in individuals who have been living with the virus for a long time.

• Mental health issues

  HIV can also affect an individual’s mental health and well-being, leading to depression, anxiety, and/or other mental health conditions.

Therefore, with proper treatment and management, many of these complications can be prevented or effectively managed. This highlights the importance of early diagnosis and treapx;tment of HIV, as well as ongoing monitoring and care.

Diagnosis

HIV infections can be diagnosed through a variety of laboratory tests that detect the presence of the virus or the immune response to the virus in your blood. The three types tests are:

• Antibody tests: These tests detect antibodies produced by your immune system in response to the HIV infection.

  Antibody tests can be performed on a blood sample, oral fluid, or urine. Most antibody tests are highly accurate, however, there is a window period during which an infected individual may test negative. This window period is typically between 2-8 weeks after nfection and can vary depending on the type of test used.

• Antigen/antibody tests: These tests detect both antibodies to HIV and the p24 antigen, a protein produced by HIV in the early stages of infection.

  Antigen/antibody tests can detect HIV infection earlier than antibody-only tests, within 2-4 weeks after infection.

• Nucleic acid tests (NATs): These tests detect the genetic material (RNA) of the virus in your blood.

  NATs are the most sensitive tests for detecting HIV infection and can diagnose HIV within days after infection, however, unfortunately they are expensive and typically used for confirmatory testing in particular situations.

If an initial HIV test is positive, additional tests are performed to confirm the diagnosis and determine the stage of infection. These tests include:

• CD4+ T cell count: assesses the immune systme's function.
• Viral load: measures the amount of virus in the blood

Treatment

HIV is treated with antiretroviral therapy (ART), medications used to target different stages of the virus's life cycle.

While the virus can not be eliminated from teh body, ART can reduce the amount of virus in your blood to undetectable levels, improve immune function, and slow the progression of HIV to AIDS. The treatment regimen typically consists of 3 or more drugs from different classes, which are generally taken daily.

The different classes of ART drugs include the following:

• Nucleoside reverse transcriptase inhibitors (NRTIs)

  These drugs block an enzyme that HIV uses to replicate itself.

  Examples include tenofovir, abacavir, and emtricitabine.

• Non-nucleoside reverse transcriptase inhibitors (NNRTIs)

  These drugs bind to a different site on the reverse transcriptase enzyme and prevent it from working.

  Examples include efavirenz, rilpivirine, and nevirapin.e

• Protease inhibitors (PIs)

  These drugs block the activity of protease, another enzyme that HIV uses to produce new virus particles.

  Examples include ritonavir, darunavir, and atazanavir.

• Integrase inhibitors (INIs)

  These drugs block the action of integrase, an enzyme that HIV uses to integrate its genetic material into the DNA of human cells.

  Examples include dolutegravir, elvitegravir, and raltegravir.

• Entry inhibitors

  These drugs block HIV from entering human cells by binding to specific receptors on the cell surface.

  Examples include enfuvirtide and maraviroc.

Combination therapy

Combination therapy typically involves 3 or more antiretroviral drugs that are generally from at least 2 different classes of drugs. This is because HIV can quickly become resistant to a single drug. By using multiple drugs that target different parts of the HIV life cycle, the virus is less likely to become resistant.

Combination therapy is often started as soon as possible after an HIV diagnosis, regardless of the individual’s CD4+ T cell count or symptoms.

Examples of combination therapy that only include NRTIs are emtricitabine/ tenofovir alafenamide fumarate (brand: Descovy), and emtricitabine/tenofovir disoproxil fumarate (brand: Truvada).

In addition to ART, individuals with HIV may also receive medications to prevent or treat opportunistic infections or other complications of HIV, including pneumonia, tuberculosis, or cancer. They may also receive supportive care, such as nutritional counseling or mental health services, to manage the physical and emotional effects of living with HIV.

It’s important for individuals with HIV to adhere to their treatment regimen and take their medications as prescribed, to prevent the virus from becoming resistant to the drugs. Regular monitoring, including viral load and CD4+ T cell count testing, is also necessary to ensure that the treatment is effective and to adjust the regimen as needed.

Prevention

There is currently no vaccine available that will prevent HIV infection. However, transmission through the most common routes (sexual contact or sharing needles) are almost completely preventable.

Some ways to prevent HIV include the following:

• Use condoms

  Condoms are highly effective at preventing the transmission of HIV and other sexually transmitted infections. Using condoms consistently and correctly during all sexual activities can ultimately reduce your risk of HIV transmission.

• Take pre-exposure prophylaxis (PrEP)

  PrEP involves taking a daily medication (Truvada, which is a combination of 2 antiretroviral drugs (tenofovir and emtricitabine)) that can reduce your risk of HIV transmission by up to 99% when taken consistently and correctly.

  PrEP is recommended for individuals who are at high risk of acquiring HIV, such as those who have a partner with HIV, those who engage in high-risk sexual behaviors, and/ or those who inject drugs.

• Do not share needles

  Practice harm reduction techniques when using drug, such as using clean needles and not sharing needles or other drug equipment.

• Regular testing

  Practice harm reduction techniques when using drugs: If you use drugs, there are ways to reduce the risk of HIV transmission, such as using clean needles and not sharing needles or other drug equipment.

• Treat HIV infection

  Individuals who are living with HIV can reduce the risk of transmitting the virus to others by taking antiretroviral therapy (ART) as prescribed and achieving and maintaining an undetectable viral load.

• Use post-exposure prophylaxis (PEP)

  PEP involves taking a combination of medications within 72 hours of a potential exposure to HIV. PEP can reduce your risk of HIV transmission if started promptly after exposure.

  PEP is a short-term medication regimen that is taken after an individual has been potentially exposed to HIV.

  PEP involves taking a combination of 3 antiretroviral drugs for 28 days, starting as soon as possible after exposure.

  PEP can reduce your risk of HIV infection by up to 81%, however, its most effective when started within 72 hours of exposure.