Bacterial

Chlamydia

The most common curable STI — silent in most people who have it.

Cause

Bacterium (C. trachomatis)

Asymptomatic

~70–90% of cases

Curable

Yes — antibiotics

Vaccine

Overview

Chlamydia is caused by the bacterium Chlamydia trachomatis. It is the most frequently diagnosed STI in Europe and North America. Because up to 90% of infections cause no symptoms, most people spread it without knowing. Routine testing is the primary way infections are detected.

How it spreads

Vaginal sex (both directions)
Anal sex (both directions)
Oral sex — less common, but throat and rectal infections are possible
Sharing sex toys without cleaning between uses

Symptoms

Unusual discharge from the penis or vagina
Burning or pain during urination
Pain or swelling in the testicles
Rectal pain or discharge
Cervical inflammation (cervicitis)

70–90% of people with chlamydia have no symptoms. Untreated infections can cause pelvic inflammatory disease (PID), infertility, and increased HIV susceptibility. Regular testing (at least annually if sexually active) is recommended.

Vaccine

No vaccine is currently available for Chlamydia.

Treatment

Chlamydia is fully curable with a single dose of azithromycin or a 7-day course of doxycycline. Sexual partners should also be tested and treated. Re-infection is common — test again after 3 months.

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Educational purposes only. Consult a healthcare provider for personal medical advice.