Human Immunodeficiency Virus (HIV) causes the condition known as AIDS (Acquired Immunodeficiency Syndrome). The disease is caused by a retrovirus which has the ability to use both RNA (ribonucleic acid) and DNA (deoxyribonucleic acid) to infect and multiply in cells. There are two types of the HIV virus, namely HIV-1, which is responsible for a worldwide epidemic, and HIV-2, which is limited to West Africa, according to the Merck Manual Online Medical Library. Scientists think the HIV virus originated from a monkey virus that infected chimpanzees. The virus mutated, which gave it the ability to infect humans.
Transmission
HIV is spread primarily from having unprotected sex with an infected person. It is believed that unprotected anal sex is riskier than unprotected vaginal sex, the Centers for Disease Control and Prevention (CDC) reports. Sharing of needles, syringes, water or drug equipment from an infected person may spread the virus. Having multiple sex partners also increases the risk of HIV, especially if the partners have other STDs (sexually transmitted diseases) like gonorrhea and syphilis. These diseases manifest as open sores on the genitals that may allow the HIV virus to spread. Infected mothers may also spread the HIV virus to their children during pregnancy, child birth or breastfeeding, according to the CDC.
Mode of Infection
The HIV virus attaches to T-Lymphocyte cells in the body that are responsible for coordinating and activating the immune system. The attachment is to a receptor called the CD4 and the virus then enters the cell. The virus converts its RNA into DNA and incorporates it into the T-lymphocyte's DNA. When the T-lymphocyte tries to multiply, it makes more viruses and eventually dies when too many virus particles are made. These viruses then burst out of the cell and go on to infect other cells eventually weakening the immune system.
Symptoms
Symptoms usually show up after a few weeks and include fever, swollen lymph nodes, rash and fatigue. The HIV virus causes symptoms depending on the part of the body infected. Infection of the brain results in dementia, difficulty walking, tremors, memory loss and difficulty thinking. Kidney infections lead to fatigue, swelling in the body and urine changes. Heart infection leads to wheezing, coughing and difficulty breathing. Genital infection leads to decreased hormone levels and decreased sex drive. The weakening of the immune system increases susceptibility to infection and cancer, and this condition is known as AIDS.
Diagnosis
There are several tests for HIV, including ELISA (enzyme linked immunosorbent assay), which tests for the presence of antibodies against the HIV virus, but can only be done a few weeks or months after infection because of the time it takes to make antibodies. Newer PCR tests are available that test for HIV virus DNA. These tests are rapid, accurate and are easy to run. Another test used is viral load or P24 antigen, which detects HIV in the blood and works faster than antibody testing.
Treatment
According to the Merck Manuals Online Medical Library, although there is no cure for HIV, antiretroviral drugs are used to block the virus from replicating inside cells. Reverse transcriptase inhibitors prevent the virus from converting RNA to DNA. Protease Inhibitors prevent the activation of newly formed viruses and prevent them from infecting cells. Fusion Inhibitors prevent HIV from entering cells to infect them. Integrase Inhibitors prevent HIV DNA from integrating into human DNA.
