How HIV Is Transmitted
AIDS, acquired immunodeficiency syndrome, is caused by a lentvirus which is a part of the retro virus family, and it is called Human immunodeficiency virus or HIV. HIV causes the human immune system to get progressively weaker and in the and fail to defend itself even against a common cold. The virus targets CD4 + T helper cells, macrophages and dendritic cells which then allow opportunistic infections and cancers to take advantage of the weakened immune system. It reduces the number of CD4 + T helper cells in three different ways, first is the direct viral eradication of infected cells, second it increases the rate of apoptosis and third by destroying infected CD4 + T helper cells.
A lot of species have an infection that is caused by lentviruses which are mostly causing long-term illnesses that have a long incubation period. The transmission of a lentvirus happends as a single-stranded, enveloped virus. After they enter a cell it begins converting the viral RNA into a double stranded DNA that has been encoded via reverse transcriptase that is transported with the virus. The created DNA then becomes part of the cell nucleus and is integrated in the cellular DNA, after that the virus can become latent and is undetected by immune system or it can become transcribed thus producing more RNA genomes and viral proteins.
With that in mind there are two characterized types of HIV the first one is HIV-1 and it is highly virulent and infective, it is global and originates from a Common Chimpanzee, while the second one HIV-2 is less virulent and infective, mostly found in West Africa and their origin is from a Sooty Mangabey. There are various ways someone can get infected by HIV, but there are three main ways HIV is transmitted: trough sex (either oral, anal, vaginal), if you have been exposed to body fluids or tissues from a infected person and the third common way is transmission from a mother to child trough pregnancy or breastfeeding. Sexual transmission of HIV happends trough unprotected sex if one partner has HIV.
Transmission of HIV trough anal intercourse has around 1.7% chance of happening and while the risk of HIV transmission from oral sex is low it is still present and there have been reported cases of HIV infections happening after having oral sex.
If a partner has sexually transmitted diseases such as genital ulcers the risk increases qintuple and a small increase if the partner has gonorrhea, clamydia, bacterial vaginosis, also it is important to note that rough sex seems to increase risk also because it can cause cuts and cracks in the soft skin during intercourse and allow the virus to easily enter the bloodstream.
During the first two and a half months after exposure to HIV a person is twelve times more infectious because of the high viral load, and when the disease enters late periods the rates of transmission increasy by eight times. Practicing comercial sex has a risk of male to female transmission 0.08% and female to male 2.4% per act. Sexual assault increases the risk of HIV transmission because protection is rarely used and there is a chance of physical trauma occuring during sex which will enable the virus to enter the bloodstream and thus increasing the risk of an infection.
HIV infection occuring trough transmission from body fluids is the second common way, though it is important to note mosquitos or other insects can not transmit HIV. Sharing a needle is dangerous and it has an average risk of HIV transmission at 0.8% (although it varies from 0.63 – 2.4%), and the risk of acquiring HIV if you use the needle from a HIV infected person is around one in three hundread. In the USA drug users made 12% of new cases in 2009.
HIV transmission trough blood transfusions results with a infection 93% of the time, and while the risk in developed countries is very low due to the regular screening of donor blood (1 in 5 million) the risk in low income countries is higher because not all donor blood gets screened and around 15% of infections come from transfusions of infected blood.
In sub-Saharian Africa 12-17% cases is attributed to the reuse of syringes in 2009. There are big chances of transmission happening during a invasive procedure, assisted delivery, dental care in this area of the world. If we consider the chance of transmission from a unsafe injection (1.2%) then theoretically people that are receiving tattoos or piercings are also at risk of HIV infection.
Mother to child transmission is the third main way of HIV transmission. The transmission can happen during pregnancy, delivery or breastfeeding, and while the risk of transmission during birth is 20% and breastfeeding 35% it can get reduced with proper treatment to 1%. In order for the treatment to work the mother and infant take antiretrovirals and doesn’t breastfeed as well as giving birth with an caesarean section.