What are STDs?

STD stands for Sexually Transmitted Disease. These are diseases caused by a pathogen (e.g. virus, bacterium, parasite, fungus), transmitted between humans mainly through sexual intercourse (vaginal sex, oral sex, anal sex).

These diseases were known as "venereal diseases" until the 1990s: Veneris is the Latin genitive (possessive) form of the name Venus, the Roman goddess of love. Nowadays, newer terms like sexually transmitted diseases (STD) or sexually transmitted infections (STI) have been introduced in order to make the warning more clear to the public.

However, some physicians make a clear distinction between STD and STI. On one hand an infection presupposes the presence of a germ (virus, bacteria or parasite) that can cause disease inside the person's body. But, an infected person does not necessarily have symptoms that the germ is actually harming their body. On the other hand a disease means that the germ is actually harming a person's body. Infection is a much broader term.

Most of the STIs are transmitted through the mucous membranes of the penis, vulva and rarely the mouth. There are STIs that can be transmitted by direct skin contact such as Herpes simplex and HPV (Human Papillomavirus).

STDs occur mostly in sexually active teenagers and young adults, the majority having multiple sex partners. According to the Centers for Disease Control and Prevention there are over 15 million cases of sexually transmitted diseases reported annually in the United States.

Many STDs do not cause very harmful diseases. Some persons carry the disease for longer periods, during which they are contagious.

There are cases, in persistent infections, when the pathogen escapes detection by the immune system and remains inactive, causing no overt disease. This is known as "latency". Nevertheless, the infection may be reactivated by multiple factors: stress, immune suppression, injury etc. Reactivated diseases can be asymptomatic (e.g. Chlamydia) or overt (e.g. genital herpes), and even fatal (e.g. HIV/AIDS, hepatitis).

STD infection can have severe consequences, if not treated: pelvic inflammatory disease (PID) and inflammation of the cervix (cervicitis) in women, inflammation of the urethra (urethritis) and inflammation of the prostate (prostatitis) in men, and fertility and reproductive system problems in both sexes. Some of them can be even fatal.

STD infection during pregnancy may have serious consequences on the fetus: stillbirth, blindness and permanent neurological problems are just a few of them.