Acquired immunodeficiency syndrome (AIDS) is the last stage of a disease caused by two lentiviruses, human immunodeficiency virus types 1 and 2 (HIV-1 and HIV-2).
Origin of HIV
- Most emerging diseases affecting humans come from wildlife; it is often human behavior that is to blame for the spillover.
- Human immunodeficiency virus (HIV) infection is no exception. The virus responsible for attacking the immune system is zoonotic, which means it transferred to humans from nonhuman primates (a type of chimpanzee, subspecies Pan troglodytes) in Central and West Africa.
- The chimpanzee version of the virus called simian immunodeficiency virus (SIV) was probably passed to humans when humans hunted these chimpanzees for meat and came in contact with their infected blood.
- The earliest known case of HIV-1 infection in human blood is from a sample taken in 1959 from a man who died in Kinshasa in the Belgian Congo (now Kinshasa in the Democratic Republic of the Congo) in the 1920s.
- Over decades, HIV has slowly spread across Africa and later into other parts of the world. The virus has shown its existence in the United States since the mid to late 1970s.
According to the natural transfer theory (hunter theory), the plausible explanation for the cross-species transmission of SIV or HIV (post mutation) is that the virus was transmitted from an ape or monkey to a human when a hunter or bushmeat vendor was bitten while hunting or butchering the animal. The resulting exposure to blood or other bodily fluids of the animal resulted in an HIV infection.
2 types of HIV
- HIV-1: More virulent, easily transmitted and is the cause of most human immunodeficiency virus (HIV) infections globally.
- HIV-2: Less transmittable and is largely confined to West Africa.
What are the symptoms of HIV?
People may have flu-like symptoms within two to four weeks after getting infected (acute human immunodeficiency virus infection), lasting for a few days or several weeks.
Symptoms may include:
- Night sweats
- Muscle aches
- Sore throat
- Swollen lymph nodes
- Mouth ulcers
How does HIV spread?
Initially, symptoms can be mild. Hence, people with human immunodeficiency virus (HIV) infection might not know they are infected and can spread HIV to others without knowing it.
HIV can spread
- During sex (anal and vaginal sex)
- By sharing needles to inject drugs or get tattoos
- By getting stuck with a needle with an infected person's blood on it
- Through infected blood transfusion
- From mother to child during pregnancy, childbirth, or breastfeeding
HIV does not spread through
3 stages of human immunodeficiency virus (HIV) infection
Stage I: Acute HIV infection
- A huge number of HIV is present in the blood, making the person contagious.
- The body’s 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 (viral load) 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 (AIDS)
- 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.
8 ways to protect yourself from HIV
- Avoid intercourse with an unknown partner
- Be in a monogamous relationship
- Use a condom every time you have sex (anal, oral, and vaginal)
- Do not share needles
- Reduce the number of sexual partners
- Get regularly tested for human immunodeficiency virus (HIV) and make sure all partners do too
- Get tested and treated for other sexually transmitted diseases (STD); having an STD increases the risk of HIV infection
- Use condoms even if you are infected to prevent infection by another strain of HIV
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Health Solutions From Our Sponsors
KidsHealth. How Do People Get AIDS? https://kidshealth.org/en/teens/aids.html
Sharp PM, Hahn BH. Origins of HIV and the AIDS pandemic. Cold Spring Harb Perspect Med. 2011;1(1):a006841. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3234451/
HIV.gov. A Timeline of HIV and AIDS. https://www.hiv.gov/hiv-basics/overview/history/hiv-and-aids-timeline
Centers for Disease Control and Prevention. About HIV. https://www.cdc.gov/hiv/basics/whatishiv.html
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Human Immunodeficiency Virus (HIV)HIV (human immunodeficiency virus) infection left untreated causes AIDS (acquired immunodeficiency syndrome). The human immunodeficiency virus (HIV) is a type of virus called a retrovirus, which can infect humans when it comes in contact with tissues that line the vagina, anal area, mouth, or eyes, or through a break in the skin. HIV infection is generally a slowly progressive disease in which the virus is present throughout the body at all stages of the disease. Three stages of HIV infection have been described. The initial stage of infection (primary infection), which occurs within weeks of acquiring the virus, often is characterized by the flu- or mono-like illness that generally resolves within weeks. The stage of chronic asymptomatic infection (meaning a long duration of infection without symptoms) lasts an average of eight to 10 years without treatment. The stage of symptomatic infection, in which the body's immune (or defense) system has been suppressed and complications have developed, is called the acquired immunodeficiency syndrome (AIDS). The symptoms are caused by the complications of AIDS, which include one or more unusual infections or cancers, severe loss of weight, and intellectual deterioration (called dementia). When HIV grows (that is, by reproducing itself), it acquires the ability to change (mutate) its own structure. These mutations enable the virus to become resistant to previously effective drug therapy. The goals of drug therapy are to prevent damage to the immune system by the HIV virus and to halt or delay the progress of the infection to symptomatic disease. Therapy for HIV includes combinations of drugs that decrease the growth of the virus to such an extent that the treatment prevents or markedly delays the development of viral resistance to the drugs. The best combination of drugs for HIV are those that effectively suppress viral replication in the blood and also are well tolerated and simple to take so that people can take the medications consistently without missing doses.
Should I Take PrEP for HIV?Pre-exposure prophylaxis (PrEP) is a course of prescribed medications that people who are at risk of human immunodeficiency virus (HIV) may take to prevent infection. This medication is administered to individuals who have tested negative for HIV but are at a high risk of HIV infection.
What Are the First Signs of HIV?Initial signs and symptoms of HIV generally appear within two to four weeks of infection. Fever, body aches, muscle aches, chills, sore throat, headache, rash, night sweats, fatigue, mouth ulcers, and swollen lymph nodes (glands) are possible first signs and symptoms.
What Are the Four Stages of HIV?The World Health Organization (WHO) classifies human immunodeficiency virus (HIV) into four stages. Stage 1 (HIV infection): The CD4+ cell count is at least 500 cells per microliter. Stage 2 (HIV infection): The CD4+ cell count is 350 to 499. Stage 3 (advanced HIV disease or AHD): The CD4+ cell count is 200 to 349. Stage 4 (Acquired immunodeficiency syndrome [AIDS]): The CD4+ cell count is less than 200.
What Does HIV Do to a Person?Human immunodeficiency virus (HIV) attacks and weakens the immune system, impairing the body's ability to fight diseases and infections.
What Is the Difference Between HIV-1 and HIV-2?There are two main types of the human immunodeficiency virus (HIV), HIV-1 and HIV-2. HIV-1 is the most common type of HIV and accounts for 95% of all infections, whereas HIV-2 is relatively uncommon and less infectious. HIV-2 is mainly concentrated in West Africa, is less deadly and progresses more slowly.
What Is Usually the First Sign of HIV?Human immunodeficiency virus (HIV) attacks the cells of the immune system, leading to AIDS and death if left untreated. The first signs of the human immunodeficiency virus infection are flu-like symptoms, which mainly start around two to four weeks after getting HIV. This stage is known as acute HIV infection.
When Should I Test for HIV?The CDC recommends everyone between 13 and 64 should get tested for human immunodeficiency virus (HIV) at least once in their lifetime. If you've had unprotected sex with a new or multiple partners, pregnant women, intravenous drug users, are being treated for a STD, have tuberculosis, or hepatitis, are also reasons to get screened and tested.