STIs can spread as a result of:
- coming into direct contact with a lesion or sore
- coming into close personal contact (in the case of crabs)
- being exposed to infected blood
- coming into contact with vaginal fluid or semen
- sharing needles
STIs come in three categories:
Bacterial and viral STIs hide in various bodily fluids, such as vaginal secretions, semen, saliva, and blood. In some cases, coming into direct contact with a partner’s fluid is enough to spread an STI.
A person should avoid coming into contact with another person’s bodily fluid when having oral, anal, or vaginal sex. To do this, a person should practice safe sex using condoms or dental dams. These can help block contact with potentially contaminated fluids.
Other STIs, such as herpes, can spread through direct skin-to-skin contact. A person can pass herpes to their partner through oral, anal, and vaginal sex. It can also spread from a partner’s mouth to the genitals of their partner through oral sex.
STIs such as HIV and hepatitis can spread through coming into contact with infected blood. Both of these infections can spread through sex when both partners have open sores or through sharing needles.
Parasitic STIs such as pubic lice can spread through close personal contact. Lice can pass from one person’s pubic hair to that of another. A person may also contract pubic lice after coming into contact with sheets or clothing that has been in close proximity to a person’s pubic hairs.
Source Article from https://www.medicalnewstoday.com/articles/327267.php