What is HIV?

HIV originated in non-human primates and eventually spread to humans over the aeons. Even though the disease had been around for a long time, it was clinically diagnosed in the 1980s. Ever since then, it has spread all over the world, killing over 25 million people till date.

AIDS and HIV are terms that are used interchangeably even though they are not quite related. So what exactly is the difference between AIDS and HIV? Essentially, HIV is the virus that causes AIDS. It wreaks havoc on the body’s immunity system until it is incapable of fending off infections on its own. It is a retrovirus and has RNA as the genetic material.

The HIV infection spreads through the following ways

  • Unprotected sexual interaction with an already infected person.
  • Reusing needles used by an infected person.
  • From an infected mother to the baby through the placenta.
  • Blood transfusion from an infected person.

This virus has a long incubation period before it starts to attack the immune system (10 years). The immune system is the human body’s natural defence mechanism, hence HIV can make it harder for the patient to fight off infections and diseases.

HIV demolishes a particular type of WBC (White Blood Cells) and the T-helper cells. This virus also makes copies of itself inside these cells. T-helper cells are also known as CD4 cells.

Types of HIV

The two major types of HIV strains are –

HIV-1: The most common type of virus found worldwide.

  • Group M – ‘M’ stands for ‘Major’, which implies that 90% of HIV AIDS all over the world are caused by this group of HIV. There are 11 sub-types (A to K) of viruses found in this group.
  • Group N – ‘N’ stands for “non-M, non-O”. As per the data found until 2006, only 10 Group N infections had been identified.
  • Group O – ‘O’ implies ‘Outlier’ group of HIV. This virus is not usually seen outside of West-central Africa.
  • Group P – This type of virus is recently diagnosed in 2009. There’s only one case of the group-P virus found till now. This is because the virus primarily affected only simians (apes and monkeys). But a strain of this virus was isolated from a Cameroonian woman.

HIV-2: This is found primarily in Western Africa, with some cases in India and Europe. There are 8 known HIV-2 groups (A to H). HIV-2 is closely related to simian immunodeficiency virus endemic in a monkey species (sooty mangabeys).

Causes or Mode of Infection

The HIV infects the macrophages in the blood. Once they infect, the viral RNA enters the host cell and produces DNA with the help of reverse transcription. This viral DNA, then integrates into the host genome and produces multiple RNA copies by the process of transcription. These RNAs then form multiple copies of the virus and continue the infection in the same way.

At the same time, HIV also enters the T lymphocytes and continues the same set of events as it does in macrophages. This leads to a decrease in the number of helper T lymphocytes. Thus, the immunity of the body is considerably compromised. The immunity is lowered to such an extent that the infected person suffers from even minor infections, which is one of AIDS’ characteristic symptoms. Other symptoms include bouts of fever, diarrhoea and significant weight loss.

Symptoms of AIDS

The symptoms of HIV usually differ from person to person and in some cases, a patient infected with the HIV infection may not experience any symptoms at all. The common signs and symptoms of HIV include:

  • Fever
  • Chills
  • Headache
  • Joint pains
  • Sore throat
  • Muscle aches
  • Upset stomach
  • Red rashes on the skin
  • Tiredness and weakness
  • Sweating during the night
  • Swollen or enlarged Glands

The above symptoms can last from a few days to several weeks. A person with HIV often experiences no symptoms, feels healthy, and appears healthy.

Prevention of  AIDS

HIV’s infection can be detected with the help of a test called ELISA which stands for ‘Enzyme Linked Immuno Sorbent Assay’. AIDS is incurable, so far; thus, HIV prevention is the wisest option. As we have already discussed the causes of AIDS, the prevention can be deduced from them.

For example – Using disposable needles, practising safe sex, i.e., use of protection like condoms, regular health check-ups and monitoring blood transfusion and pregnancy.

Another important factor is the awareness of AIDS. As it does not spread by mere physical contact, the infected persons should not be discriminated and must be treated in a friendly manner.

Stay tuned with BYJU’S to learn more about AIDS and HIV, and other related topics @ BYJU’S Biology.



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