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What is HIV?

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HIV HIV infection is a worldwide outbreak - a deadly disease - affecting people everywhere. The spread of HIV infection has occurred on such a scale, and the impact of the disease is potentially so devastating to world health, that only a concerted, global response is appropriate. What is HIV? The human immunodeficiency virus (HIV) is an organism known as a retrovirus. Like any virus, HIV must use the cells of another organism - its host - to survive and reproduce. HIV is adapted to using the cells of the human immune system. HIV has its origin in the transmission of simian immunodeficiency viruses (SIVs) ...read more.


Sharing of needles between intravenous drug users can also result in transmission as needles may be contaminated with minute quantities of blood containing the virus. From mother to child during pregnancy, birth or breastfeeding- this is known as vertical transmission. The risk can be reduced by antiretroviral therapy for pregnant women who are infected with HIV, and by delivering babies by caesarian section. How Does it Affect People The human immune system can be regarded as an organ concerned with destroying and eliminating from the body any organism, substance or particle that threatens the body's integrity. Like the heart or the brain, an effective immune system is essential to life. ...read more.


Once the CD4+cells have captured antigens, they help B cells to make antibodies, and they release lymphokines, chemicals that stimulate other varieties of immune cell to kill the invader. Tc - cytotoxic T cells recognise and destroy cells coated with antigens (the antigen may be deposited on the surface of a cell as the virus enters, making it a target for Tc activity) NK - natural killer cells use the cell-surface changes that result from viral infection to identify and kill infected cells K - killer cells can bind to antibodies, which 'flag up' infected cells for killer cells to destroy. Granulocytes - can engulf and digest infected cells Macrophages - release chemicals that stimulate and control the actions of other effector cells, but also engulf and digest infected cells. ...read more.

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