Incubation period
1 to 3 weeks, if anything shows at all.
When a test becomes reliable
About 2 weeks after exposure. A modern NAAT test is reliable from then on.
Symptoms
- Most people have none at all — around 7 in 10 women and 5 in 10 men notice nothing
- Unusual discharge from the vagina or penis
- Burning or stinging when passing urine
- Pain low in the belly, or bleeding between periods
- Pain or swelling in one testicle
- Infections in the throat or rectum almost never cause symptoms
Good to know
- Because it is so often silent, most people who pass it on had no idea they had it
- Left alone for a long time it can scar the fallopian tubes and cause infertility
- A test on urine or a self-taken swab is enough — nothing invasive is needed
- Having had it once gives you no protection against getting it again
How it was discovered
The organism was seen in 1907 by Ludwig Halberstädter and Stanislaus von Prowazek, who scraped the eyes of orangutans they had infected with material from human trachoma patients. For the next fifty years it was filed as a virus, because it only grows inside living cells and refused to grow on the plates bacteriologists used. Only in the 1960s was it shown to have its own cell wall, its own DNA and RNA, and to be an unusually dependent bacterium rather than a virus.
Last updated: September 2026
This page is general information, not a diagnosis and not medical advice. Symptoms overlap between infections, and many infections have none at all — only a test can tell. If you think you have been exposed, talk to a doctor.