Sexually transmitted diseases (STDs) are infections that you can get from having sex with someone who has the infection. The causes of STDs are bacteria, parasites and viruses. Most STDs affect both men and women, but in many cases the health problems they cause can be more severe for women. If a pregnant woman has an STD, it can cause serious health problems for the baby.

Some common Sexually transmitted diseases:

Chlamydia:

• Chlamydia is the most common and fastest-spreading sexually transmitted disease . It's caused by a bacterium, Chlamydia trachomatis. You get it by having sex or sexual contact with someone who is infected. Both men and women can get it. Chlamydia usually doesn't cause symptoms. If it does, you might notice a burning feeling when you urinate or abnormal discharge from your vagina or penis.
• In both men and women, chlamydia can infect the urinary tract. In women, infection of the reproductive system can lead to pelvic inflammatory disease, which can cause infertility or serious problems with pregnancy. Babies born to infected mothers can get eye infections and pneumonia from chlamydia. In men, chlamydia can infect the epididymis, the tube that carries sperm. This can cause pain, fever and rarely, infertility.

Gonorrhoea:

• Gonorrhoea is caused by Neisseria gonorrhoeae, a bacterium that grows and multiplies quickly in moist, warm areas of the body – such as the cervix, urethra, mouth, or rectum. The cervix is the most common site of infection in women. However, the disease can also spread to the Fallopian tubes and other internal genital organs, causing such conditions as salpingitis and pelvic inflammatory disease. These may lead to to infertility.
• Gonorrhoea is most commonly spread during genital contact, but it can also be passed from the genitals of one partner to the throat of the other during oral sex.
• Gonorrhoea of the rectum can occur in people who practice anal sex. In pregnant women, gonorrhoea can be passed from an infected woman to her newborn infant during delivery.

Genital herpes:

Genital herpes is a highly contagious viral condition caused by the herpes simplex virus (HSV). It infects the skin and mucous membranes of the genitals or rectum, but it can also appear in areas such as the mouth, particularly the lips.Its chief symptom is an outbreak of small blisters, and these can be very painful.It's transmitted primarily through physical and sexual contact. During birth, the presence of herpes simplex virus in the birth canal is a threat to the infant's life.

HIV and AIDS:

• HIV stands for human immunodeficiency virus. It kills or damages the body's immune system cells. AIDS stands for acquired immunodeficiency syndrome. It is the most advanced stage of infection with HIV.
• HIV most often spreads through unprotected sex with an infected person. It may also spread by sharing drug needles or through contact with the blood of an infected person. Women can give it to their babies during pregnancy or childbirth.
• The first signs of HIV infection may be swollen glands and flu-like symptoms. These may come and go a month or two after infection. Severe symptoms may not appear until months or years later.

Genital warts:

• Warts, or condylomata acuminata, are caused by the human papilloma virus (HPV).
• Many months can pass from the time of infection to the actual development of warts, so it may be very difficult to determine who you got them from.
• In women, HPV can lead to microscopic changes in the cervix and to the development of cervical cancer
• HPV is now thought to be associated with various other cancers, including carcinoma of the anus and possibly of the throat and adjoining regions.

Syphilis:

• It's caused by a corkscrew-shaped germ called Treponema pallidum.
• If left untreated, syphilis is a dangerous and life-threatening disease.
• It's passed on by intercourse or by almost any other form of sexual interaction.
• The first symptom appears between 9 and 90 days after exposure to the germ that causes it. A small lump develops at the infection site, and this soon breaks down to form a painless ulcer.
• Later, there is a secondary stage (characterised by fever, rashes and throat ulcers), and eventually a tertiary stage (in which the germ may attack the brain, spinal cord and other organs).

Trichomonas:

• Trichomonas vaginalis (often known as 'TV') is a protozoan 'bug' that affects the vagina.
• It causes a green or yellowish, bubbly vaginal discharge and intense vulval soreness. It also produces a 'fishy' smell.
• However, some women have no symptoms at all, and men rarely do.

Bacterial vaginosis:

• BV is a common cause of vaginal discharge. The discharge is usually whitish or greyish or sometimes yellowish, and tends to have an off-putting ‘fishy’ odour.
• Unlike the discharges caused by thrush or trichomonas, it’s not usually associated with soreness, discomfort or itching.
• It's uncertain if BV is transmitted sexually, especially as there's no equivalent condition in males.

Scabies:

Scabies (the itch) isn't actually a genital infection. Scabies is an itchy skin condition caused by the microscopic mite Sarcoptes scabei. It is common all over the world, and it affects people of all races and social classes. Scabies can easily infect sex partners and other household members. Sharing clothes, towels, and bedding can also spread scabies.It's caused by a little mite, which is just about visible to the naked eye. If your skin comes into contact with the skin of somebody who has scabies, some of the mites may well nip across from the other person's body to yours.