What is HIV?

HIV is an acronym for human immunodeficiency virus. There are two types, known as HIV-1 and HIV-2. Both HIV-1 and HIV-1 are part of the family of Lentiviruses. A lentivirus represents a genus of slow viruses with long incubation period (months, even years). This is why is may take many years after being infected for symptoms to develop.

According to the classification of International Committee on Taxonomy of Viruses (ICTV), Lentivirus genus belongs to the family Retroviridae and currently comprises of nine species: seven animal lentiviruses and two human lentiviruses. Animal lentiviruses are: bovine immunodeficiency virus (BIV), caprine arthritis encephalitis virus (CAEV), equine infectious anaemia virus (EIAV), feline immunodeficiency virus (FIV), puma lentivirus (PLV), simian immunodeficiency virus (SIV) and visna/maedi virus (VMV). Human species are the well-known human immunodeficinecy virus 1 (HIV-1) and human immunodeficiency virus 2 (HIV-2).

HIV is a virus that attacks the immune system and weakens your ability to fight infections and disease. The virus causes a progressive failure of the immune system, allowing life-threatening opportunistic infections and cancers to thrive. Without treatment, average survival time after infection is estimated to be 9 to 11 years, depending on the subtype.

How common is HIV?
The World Health Organisation estimates that in June 2015 around 36.9 million people in the world are living with the virus (WHO statistics). It is more common in sub-Saharan African countries, such as South Africa, Zimbabwe and Mozambique. HIV is though to be on the increase in the UK and at the end of 2014, there were an estimated 103,700 people in the UK living with the virus. The majority were infected through sex. Around 17 per cent of people with HIV (over 18,100) do not know they are infected. Around one in every 360 people in the UK has the virus, but the two groups with highest rates are gay and bisexual men and Black African heterosexuals, where the rates are approximately one in 17 and one in 18 respectively. In the United States there are around 50 000 new cases per year which approximates to one person every 10 and a half minutes being diagnosed with HIV (Centre for Disease Control and Prevention) .The country with the highest prevalence rate is Swaziland with 1 in 4 people (26% of the population) infected (UNICEF Statistics)

How do you get HIV?
The virus is found in the body fluids of an infected person, which includes semen, vaginal and anal fluids, blood, and breast milk. Although the virus is considered to be a fragile virus, it can survive outside a living body for several weeks (Nyberg, Suni and Haltia,1990). HIV cannot be transmitted through sweat or urine.The most common way of getting the virus in the UK is by anal or vaginal sex without a condom. According to statistics from Public Health England, 95% of those diagnosed in the UK in 2013 acquired it as a result of sexual contact.

Other ways of getting HIV include:
Using a contaminated needle, syringe or other injecting equipment
Transmission from mother to baby during pregnancy, birth or breastfeeding
Through oral sex or sharing sex toys (although the risk is significantly lower than for anal and vaginal sex)
Laboratory work with superconcentrates of HIV
Receiving donated blood, organs or injections with unsterilised needles in countries with inadequate screening procedures

How does HIV cause illness?
The virus infects vital cells in the human immune system. In particular it affects cells, known as helper T cells, macrophages, and dendritic cells. HIV infection leads to low levels helper T cells through a number of mechanisms, including direct viral killing of infected cells. When the immune cell numbers decline below a critical level, you lose what is known as cell-mediated immunity, and the body becomes progressively more susceptible to opportunistic infections.

Most people who are infected with HIV experience a short, flu-like illness that occurs two to six weeks after infection. After this, the virus often causes no symptoms for several years.The flu-like illness that often occurs a few weeks after HIV infection is also known as seroconversion illness. It’s estimated that up to 80% of people who are infected with HIV experience this illness.

The most common symptoms are:

  • fever (raised temperature)
    sore throat
    body rash


Other symptoms can include:

  • tiredness
    joint pain
    muscle pain
    swollen glands (nodes)

The symptoms usually last one to two weeks but can be longer. They are a sign that your immune system is putting up a fight against the virus. However, these symptoms are most commonly caused by conditions other than HIV, and do not mean you have the virus. If you have several of these symptoms, and you think you have been at risk of infection within the past few weeks, you should get a HIV test. After the initial symptoms disappear, HIV will often not cause any further symptoms for many years. During this time, known as asymptomatic HIV infection, the virus continues to be active and causes progressive damage to your immune system. This process can take about 10 years, during which you will feel and appear well. Without treatment, the immune system will become severely damaged and life-threatening illnesses such as cancer and severe infections can occur. This is known as late-stage HIV infection or AIDS.

Although there is no cure for HIV, treatments are now very effective, enabling people with the virus to live long and healthy lives.