HIV is a virus that attacks the immune system, which is our body’s natural defense against illness. The virus destroys a type of white blood cell in the immune system called a T-helper cell, and makes copies of itself inside these cells. T-helper cells are also referred to as CD4 cells.
The virus is actually not one, but several different viruses in the class of Retroviridae and the genus Lentivirus. The species differs and there is a larger list of subtypes. There are two major types: HIV1 and HIV2 – HIV1 is thought to originate from chimpanzees and gorillas in western Africa; HIV2 originates from sooty mangabeys (another ape) found in Senegal and Ghana. HIV1 is the more deadly and is the cause of the AIDS pandemic and can be divided into the M, N, O, and P subgroups, but HIV2 is also known to cause AIDS.
Structure of HIV
As HIV destroys more CD4 cells and makes more copies of itself, it gradually breaks down a person’s immune system. This means someone living with HIV, who is not receiving treatment, will find it harder and harder to fight off infections and diseases. HIV spreads through bodily fluids that include:
- Vaginal and rectal fluids
- Breast milk
Replication process of HIV viruses in human body
- The virus infects the body’s macrophages, dendritic cells, and T-cells, viz. most often the CD4+ lymphocytes, by attaching itself to them via its gp120 protein to the e.g.
- T-cell’s CD4+ protein. The CCR-5 protein then induces the fusion of the membranes. An inherent property of lentiviruses is that they have a single-strand RNA strand, not DNA, and this strand is injected when the cytoplasm’s merge as the HIV’s membrane fuses with that of the T-cell.
- The RNA is converted into DNA by reverse transcriptase and is inserted into the T-cell’s genome strand using DNA integrase. Hence, the virus is literally replacing part of the human body.
- The infected T-cell now produces HIV RNA and amino acids that form new HIV viruses and their protein coats. These viruses then spread throughout the body the infection rate increases.
- The T-cells then die, causing AIDS as the immunodeficiency occurs when the majority of T-cells are denatured. At the replication of the viral RNA, which happens 10 billion times per day, there is a chance of mutation of one nucleotide per 9 200 nucleotides, meaning resistance could develop.
- The virus is then spread via blood transfusions, sexual intercourse, or during birth (i.e. mother-to-child transmission, MTCT).
- Everyday activities such as sharing food and water, kissing, shaking hand, or using the same toilet are not factors that spread the condition.
- AIDS occurs when the body catches a secondary, an opportunistic, disease due to the decreased immune defense strength.
HIV advances in stages, overwhelming your immune system and getting worse over time. The three stages of HIV infection are:
1. Acute HIV infection
The first few weeks after infection is called the acute infection stage. During this time the virus rapidly reproduces. Your immune system responds by producing HIV antibodies. Many people experience temporary flu-like symptoms during this stage. Even without symptoms, HIV is highly contagious during this time. Some of the symptoms during this stages includes:
- Fever (raised temperature)
- Body rash
- Sore throat
- Swollen glands
- Upset stomach
- Joint aches and pains
- Muscle pain.
2. Clinical latency
After the first month or so, HIV enters the clinical latency stage. This stage can last from a few years to a few decades. Progression can be slowed with antiretroviral therapy. Some people have symptoms. Many people do not, but it’s still contagious. As the virus progresses, you’re left with fewer T cells. This makes you more susceptible to disease, infection, and infection-related cancers.
3. AIDS (acquired immunodeficiency syndrome)
Without treatment, HIV is likely to advance to AIDS. At that point, the immune system is too weak to fight off life-threatening disease and infection. Untreated, life expectancy with AIDS is about three years.
AIDS is a disease caused by HIV. It’s the most advanced stage of HIV. But just because you have HIV doesn’t mean you’ll develop AIDS. HIV destroys T cells called CD4 cells. These cells help your immune system fight infections. Healthy adults generally have a CD4 count of 800 to 1,000 per cubic millimeter. If you have AIDS and your CD4 count falls below 200 per cubic millimeter, you will be diagnosed with AIDS.
You can also be diagnosed with AIDS if you have HIV and develop an opportunistic infection that is rare in people who don’t have HIV. AIDS weakens your immune system to the point where it can no longer fight off most diseases and infections. That makes you vulnerable to a wide range of illnesses, including:
- Cytomegalovirus, a type of herpes virus
- Cryptococci meningitis
- Toxoplasmosis, an infection causes by a parasite
- Cryptosporidiosis, an infection caused by an intestinal parasite
- Cancer, including Kaposi’s sarcoma (KS) and lymphoma
- Kidney disease
Symptoms that you may have during this time can include:
- Weight loss
- Chronic diarrhea
- Night sweats
- A fever
- A persistent cough
- Mouth and skin problems
- Regular infections
- Serious illnesses or diseases
Historical view of HIV/AIDS
Researchers found the earliest case of AIDS in a blood sample of a man from the Democratic Republic of Congo. It’s said that the virus spread from chimpanzees to humans sometime before 1931, most likely during “bush meat trading.” While hunting chimpanzees, hunters would come in contact with animal blood.
Before the 1980s, researchers estimate that about 100,000 to 300,000 people were infected with HIV. The earliest case was confirmed in 1968, in Robert Rayford, a 16-year-old teenager, who never left the Midwest or received a blood transfusion. This suggests that AIDS may have been present in the United States before 1966.
But before AIDS was identified, the disease appeared as other immunodeficiency conditions like Pneumocystic carinii pneumonia (PCP) and Kaposi sarcoma (KS). A year after scientists identified AIDS they discovered the cause: HIV.
Epidemiology in worldwide
Since the beginning of the epidemic, more than 70 million people have been infected with the HIV virus and about 35 million people have died of AIDS. Globally, 36.7 million [30.8–42.9 million] people were living with AIDS at the end of 2016. An estimated 0.8% [0.7-0.9%] of adults aged 15–49 years worldwide are living with AIDS, although the burden of the epidemic continues to vary considerably between countries and regions. Sub-Saharan Africa remains most severely affected, with nearly 1 in every 25 adults (4.2%) living with AIDS and accounting for nearly two-thirds of the people living with AIDS worldwide.
Statistics on causes of HIV/AIDS
Causes or Possibilities of HIV/AIDS
Some of the ways AIDS is spread from person to person include:
- Having unprotected sex with an infected person. This is the most common route of transmission
- Sharing needles, syringes, and other items for injection drug use with an infected person
- Passing it on to an unborn child if the mother is HIV-positive
- Passing it on to a baby through breast milk if the mother is HIV-positive
- Being exposed to infected fluids, usually through needle sticks.
- Having a blood transfusion or organ and tissue transplant can also transmit the virus. But rigorous testing for HIV in blood ensures that this is very rare in the United States.
It’s theoretically possible, but considered extremely rare, for AIDS to spread via:
- Oral sex
- Being bitten by an infected person
- Contact between broken skin, wounds, or mucous membranes and AIDS-infected blood or fluids
AIDS does NOT spread through:
- Skin-to-skin contact
- Hugging, shaking hands, or kissing
- Air or water
- Eating or drinking items, including drinking fountains
- Saliva, tears, or sweat (unless mixed with blood from an infected person)
- Sharing a toilet, towels, or bedding
- Mosquitoes or other insects
Complications during HIV
- Sexually transmitted infections
- Liver or kidney damage
- Urinary tract infection
Testing and Screening of HIV (Diagnosis)
There are four main types of HIV test:
- Antibody Screening Tests: These tests check for a kind of protein that your body makes in response to the HIV infection, 2-8 weeks later. They’re also called immunoassay or ELISA tests.
- Antibody/Antigen Combination Tests: The CDC recommends these blood tests. They can detect HIV as soon as 20 days earlier than antibody screening tests. They check for HIV antigen, a protein called p24 that’s part of the virus that shows up 2-4 weeks after infection, as well as HIV antibodies. A rapid antibody/antigen test can give you results in 20 minutes.
- RNA Test: This looks for the virus itself and can diagnose HIV about 10 days after you’ve been exposed. It’s expensive, though, so it’s usually not the first test. But if you’re at high risk and you have flu-like symptoms, your doctor may want to use it.
- In-Home Test Kits: Two kits are available. One option is to prick your finger to get a small blood sample that you send to a lab. For the other, you’ll swab your upper and lower gums and test the sample in a vial. You get a result in 20 minutes.
- Western blot or indirect immunofluorescence assay
- HIV-1 nucleic acid test, which looks for the virus itself
Treating of HIV/AIDS
The classes of anti-HIV drugs include:
- Non-nucleoside reverse transcriptase inhibitors (NNRTIs). NNRTIs disable a protein needed by HIV to make copies of itself. Examples include efavirenz (Sustiva), etravirine (Intelence) and nevirapine (Viramune).
- Nucleoside or nucleotide reverse transcriptase inhibitors (NRTIs). NRTIs are faulty versions of building blocks that HIV needs to make copies of itself. Examples include Abacavir (Ziagen), and the combination drugs emtricitabine-tenofovir (Truvada), and lamivudine-zidovudine (Combivir).
- Protease inhibitors (PIs). PIs disable protease, another protein that HIV needs to make copies of itself. Examples include atazanavir (Reyataz), darunavir (Prezista), fosamprenavir (Lexiva) and indinavir (Crixivan).
- Entry or fusion inhibitors. These drugs block HIV’s entry into CD4 cells. Examples include enfuvirtide (Fuzeon) and maraviroc (Selzentry).
- Integrase inhibitors. These drugs work by disabling integrase, a protein that HIV uses to insert its genetic material into CD4 cells. Examples include raltegravir (Isentress), elvitegravir (Vitekta) and dolutegravir (Tivicay).
- Fusion Inhibitors: Fusion inhibitors are a new class of drugs that act against HIV by preventing the virus from fusing with the inside of a cell, preventing it from replicating. The group of drugs includes Enfuvirtide, also known as Fuzeon or T-20.
- Antiretroviral therapy (ART) is the use of AIDS medicines to treat HIV infection. People on ART take a combination of AIDS medicines (called an HIV regimen) every day. ART is recommended for everyone infected with HIV. ART can’t cure HIV, but HIV medicines help people with HIV live longer, healthier lives. ART also reduces the risk of HIV transmission.
Prevention of AIDS
Because the most common ways AIDS is transmitted is through anal or vaginal sex or sharing drug injection equipment with a person infected with AIDS, it is important to take steps to reduce the risks associated with these. They include:
- Know your AIDS status. Everyone between the ages of 13 and 64 should be tested for HIV at least once. If you are at increased risk for AIDS, you should be tested for HIV at least once a year.
- If you have AIDS, you can get medical care, treatment, and supportive services to help you stay healthy and reduce your ability to transmit the virus to others.
- If you are pregnant and find positive, treatments are available to reduce the chance that your baby will have AIDS.