To answer this question requires a brief understanding of HIV. HIV (Human Immunodeficiency Virus) is, as its name suggests, a virus of the human immune system. HIV is a type of virus that integrates its DNA into the host cell. In the case of HIV, the host cell is CD4 T cells. Which are cells responsible for controlling and directing the body's immune system. In short, HIV integrates its DNA into the T cell to allow replication of viral DNA and proteins. The virus hijacks the function of T cells to make more copies of the virus. More copies of the virus are released until the host cell dies. Say no to plagiarism. Get a tailor-made essay on "Why Violent Video Games Shouldn't Be Banned"? Get an original essay The key to why HIV is so deadly lies in this mechanism, because the host cell is destroyed and HIV replicates much faster than CD4 T cells, individuals infected with the virus will eventually become immunocompromised . Quantitative analysis of the number of CD4 cells in an HIV-infected individual is important in determining the progression of the virus. HIV patients who have less than “200 (CD4) cells/mm3” have progressed to the AIDS (advanced immunodeficiency syndrome) stage of the virus. This is of particular importance because it means that the individual is now susceptible to “opportunistic infections” which are the leading cause of death among HIV-infected individuals. The self-defined term opportunistic infections (OI) refers to any secondary systemic infection that occurs in individuals with HIV. OI may be a viral/fungal/bacterial infection or may refer to the incidence of cancer caused by viruses in HIV-infected individuals. The most common OIs for HIV patients include Pneumocystis pneumonia, Kaposi's sarcoma, progressive multifocal leukoencephalopathy, cerebral toxoplasmosis, and tuberculosis. In a study published by The Journal of Infectious Diseases, 71% of 20,858 individuals reported HIV deaths were due to OI. Individuals with AIDS who are severely immunocompromised are unable to fight off the secondary infection, and the cause of death is usually attributed to the infection. HIV allows other more serious and life-threatening infections to take hold, it is not HIV that kills the individual, rather it is the more serious opportunistic infections.