If you have chlamydia, you can pass it on to someone else when your mucous membranes come into contact with either their mucous membranes or their sexual secretions, such as semen or vaginal fluid. With chlamydia, this kind of transfer mostly occurs when people have either vaginal or anal sex without the use of a latex condom. You can also give someone else chlamydia through oral sex, but it’s less likely.

More Key Facts About Chlamydia

Here are some other vital points to understand about transmission of chlamydia, from the American Sexual Health Association:

The penis or tongue of the person with chlamydia does not need to fully enter the vagina or anus of a sex partner for the infection to be passed on. If even a tiny amount of infected secretions or fluid, such as semen, reaches the vagina, cervix, anus, mouth, or penis of a sex partner, that partner can catch chlamydia.

Oral sex is not a common method for giving a sex partner chlamydia, although you can pass the infection on orally. The bacteria that cause chlamydia thrive more readily in the genitals than they do in the mouth and throat. For this reason, mouth-to-penis and penis-to-mouth contacts are not a frequent route for chlamydia transmission. Still, as mentioned above, sometimes oral sex does cause chlamydia to pass from an infected to an uninfected person. In the same vein, transmission is not likely to occur through mouth-to-vagina or mouth-to-anus contacts.

If you are a woman, you can get chlamydia in your anus or rectum even if you don’t have anal sex. The infection can spread from the vaginal area to the anus when you wipe from front to back with toilet paper.

Chlamydia can infect your eyes if they come into contact with an infected partner’s secretions during sex. You can also infect your own eyes if you have genital secretions on your hand and touch your eye.

An infected mother can infect her baby during a vaginal delivery, and this can do the baby serious damage or kill the baby. The baby may develop an eye infection, pneumonia, or other problems.

Chlamydia increases the odds that a pregnancy will end in miscarriage, preterm birth, or stillbirth. (4)

You cannot get a chlamydia infection by shaking hands with an infected person or by sitting on a toilet seat used by someone with the illness.

Also, anytime a child contracts an STD such as chlamydia, the possibility of sexual abuse arises and calls for investigation.

Repeat Infections Often Occur

It is important to know that people who contract one case of chlamydia once often go on to have later infections as well. Say you get treated and your body is cleared of chlamydia but your partner does not get any treatment. That partner, or other partners who have chlamydia but don’t realize it, can easily reinfect you.

This is why the CDC recommends annual screenings for many young people, and for some older people as well, if their sexual habits put them at high risk for infection and reinfection.

“When you have treatment, you have to get your partner treated as well,” says Rabin. “If you have more than one partner, they should all be treated.” It doesn’t matter if one partner is one gender and the other partner is a different gender.

All your partners, whatever their gender, need to take antibiotics to cure the infection. You and your partners need to be careful to follow the instructions your doctor or other healthcare provider gives you about taking the medicine.

“Then you get retested in three or four months to make sure the chlamydia is cured,” says Rabin. The medicine works nearly all the time, she says, provided that your partner(s) also took the antibiotics and none of you had sex while you were taking the drugs.

The treatment for chlamydia involves only common antibiotics, which are generally free from serious side effects.