What is HIV ?

HIV is transmitted from one infected person to another through penetrative sexual acts, both heterosexual and homosexual, through a contaminated blood transfusion or sharing of needles and syringes , and from mother to child in pregnancy or in breast feeding, Initially they are called HIGH RISK GROUPS , the population most vulnerable to HIV are compromised of sex worker(male and female), men having sex with men, Transgender, and injecting drug user.

By the end of 2013, an estimated 35 million (33.1 million - 37.2 million) people were infected with HIV globally. The average adult prevalence was 0.8 percent. Of the total number of infections 3.2 million occurred in children (individuals less than 15 years of age). Of the total number, 2.1 million were new infections – illustrating an overall decline in the number of new infections. Over the decade, thirty-three countries reported a decline in the incidence of HIV;two thirds, of the remaining countries, showed a stable incidence rate; and the remaining third showed an increasing incidence rate. Over the past five years, there has been a 19 percent decline in AIDS related deaths

HIV infects vital cells in the human immune system such as Helper T cells (specifically CD4⁺ T cells), macrophages , and dendritic cells. HIV infection leads to low levels of CD4+ T cells through a number of mechanisms, including pyroptosis of abortively infected T cells, apoptosis of uninfected by standers cells, direct viral killing of infected cells, and killing of infected CD4⁺ T cells by CD8 cytotoxic lymphocytes  that recognize infected cells. When CD4⁺ T cell numbers decline below a critical level, cell mediated immunity is lost, and the body becomes progressively more susceptible to opportunistic infections.

What is CD4 cells ?

CD4+ T helper cells  are the white blood cells that are an essential part of the human immune system. They are often referred to as CD4 cells, T-helper cells or T4 cells. They are called helper cells because one of their main roles is to send signals to other types of immune cells, including CD8 killer cells, which then destroy the infectious particle. If CD4 cells become depleted, for example in untreated HIV infection, or following immune suppression prior to a transplant, the body is left exposed  to a wide range of infections that it would otherwise have been able to fight like Tuberculosis, Pneumonia, common cold etc. 

The full form of CD4 cells are clusters of differentiation 4 is a Glycoprotein  found on the surface of immune cells such as T helper cells, monocytes, macrophages, and dendritic cells. Just like the paint on wall , or at any surface.

Unlike some other viruses, the human body can’t get rid of HIV completely. So once you have HIV, you have it for life. The CD4 cell count of a person who does not have HIV can be anything between 500 and 1500 People living with HIV who have a CD4 count over 500 are usually in pretty good health.People living with HIV who have a CD4 cell count below 200 are at significant risk of developing serious illnesses. While HIV treatment is recommended for all people living with HIV, it is especially important for people with low CD4 counts.If you have HIV and do not take HIV treatment, your CD4 count will fall over time. The lower the CD4 cell count, the greater the damage to the immune system and the greater the risk of illness

Without treatment, people who are diagnosed with AIDS typically survive about 3 years. Once someone has a dangerous opportunistic illness, life expectancy without treatment falls to about 1 year. People with AIDS need medical treatment to prevent death.