The findings show that younger women are more susceptible to and do not understand the risks of not only Chlamydia, but other STDs as well, the researchers said.

Chlamydia is the most common STD among women and, in 70 percent of cases, causes no symptoms. The bacterial infection can lead to pelvic inflammatory disease, ectopic pregnancy and infertility. It can also make a woman more likely to be infected with or to pass on the AIDS virus.
The researchers tested nearly 40,000 women in two studies, one in 2000 and another from 2003 to 2004. One in eight women diagnosed with Chlamydia citywide had a repeat infection within 1 year. The women younger than 19 were much more likely to have been infected repeatedly than women older than 25, they found. A study of 400,000 women making routine doctor visits in California found similar rates, with 1 in 10 infected with Chlamydia becoming reinfected within 6 months.

Doctors and clinics need to work harder to get women to notify their sexual partners, routinely re-screen women, and perhaps try innovative approaches such as giving the women antibiotics to take to their partners.