How does HIV spread from one person to another ?
HIV infection spreads through four main routes:
Injections, especially intravenous drug injections and
Mother to child transmission during pregnancy or delivery
It is important to note that more than 74 percent people are estimated to have got the infection through sexual transmission.
The effectiveness of transmission of virus routes is not the same. Effectiveness of transmission means the probability of getting the infection with one encounter with the virus through the route.
The effectiveness is often expressed as percentage. This means the number of times a person can get HIV infection through exposures to the route of transmission.
It is important to remember that although sexual route has a very low effectiveness of transmission, it accounts for more than 74 percent infections in India.
This is mainly because of the high frequency of occurrence of sex acts among people as compared to the frequency with which people take intravenous drugs or get blood transfusions.
HIV is present in all body fluids of an infected person. It is however more in number in blood, semen and vaginal fluids. Semen is the thick whitish secretion of the male reproductive organs that is discharged from the same opening through which the urine comes out.
Vaginal fluids are the secretions from the vagina, which is like a canal in the female reproductive system. It starts at the opening of the womb or uterus, and opens out of the body just behind the opening for urine and in front of the opening for stool.
HIV virus can be easily killed by heat and by drying.
There are four main conditions that must be fulfilled, for HIV to be spread from one person to another, through any one of the four routes mentioned above.
– HIV must be present in the body fluids, especially the semen, vaginal fluids, blood.
– HIV must leave during the period it is out of the body. It can live for a long time in blood stored at cold temperature for transfusion but lives for a very short time in all other situations as the body fluids easily dry. HIV cannot survive in dried body fluids.
– There must be a convenient place for the virus to enter the body. The normal skin forms a very effective barrier against HIV and will find it difficult to enter the body through intact skin.
The virus can easily enter the body from where there is either damage to the skin or a delicate skin. Anus is the opening of the digestive tract through which stool is passed out of the body.
– The number of viruses in the body fluids must be adequate to infect others after it is transferred on contact with body fluids. If the number of viruses that enter another person is less, the infection may not occur.