Human Immunodeficiency Virus (HIV)

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Human Immunodeficiency Virus (HIV)

Life History

The human immunodeficiency virus (HIV) is an obligate intracellular parasite found exclusively in humans. It is responsible for weakening the immune system and leading to acquired immunodeficiency syndrome (AIDS). The first case of AIDS was diagnosed in the U.S. in 1981, and in 1984 it was first proven that HIV caused AIDS. There is currently a pandemic of HIV/AIDS, with the highest incidence rate in Sub-Saharan Africa and the lowest rates in Western Europe and North America, due to better healthcare.


HIV is spread by sexual contact or blood-to-blood contact. HIV is most commonly spread by sexual contact, including vaginal, anal and oral sex. Another important mode of transmission is the sharing of needles used for intravenous drug use. HIV can be acquired from mother to fetus during pregnancy or from breast milk during nursing. Blood transfusions are becoming a rarer source in developed countries because donated blood is now tested for the presence of HIV. Healthcare workers must take extra precautions because they can contract HIV if stuck by an infected needle or if infected blood contacted their mucous membranes. Individuals with other STDs are at increased risk of contracting HIV.

Microbiological Characteristics and Virulence Factors

HIV is a retrovirus with a genome consisting of two identical RNA molecules linked in a dimeric structure. Retroviruses use an enzyme called reverse transcriptase to synthesize DNA that is then incorporated into the genome of the host cell, forming a provirus. HIV belongs to a subgroup known as lentiviruses (“slow” viruses) that have a long period of time between the initial infection and the onset of serious sympto...

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...g women, with half of these new cases in people under 25.Of the approximately 42 million cases of HIV/AIDS worldwide, Sub-Saharan Africa has the vast majority (70%), followed by Southeast Asia (17%) and other developing nations with lower opportunities for proper healthcare. In the U.S., it is estimated that 850,000-950,000 people are living with HIV infection. HIV infection is more common in African-Americans, especially in adolescents. HIV/AIDS is now the second leading cause of death worldwide, and the fifth leading cause of death in Americans aged 25-49. It is the leading cause of death of African Americans in this age group.


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