Post updated 12/16/14 with response from St. Louis City Health Department.

A new federal report shows that the city of St. Louis had the highest rate of chlamydia and the second-highest rate of gonorrhea infections among major U.S. cities in 2013.

"We've had persistently high rates for a long time," said Brad Stoner, who directs the St. Louis STD and HIV Prevention Training Center at Washington University. "These rates are difficult to bring down unless we develop a concerted, community-wide effort to reach out, screen and treat populations at risk."

According to historical numbers provided by the St. Louis City Health Department, the number of reported chlamydia cases have been relatively stagnant since 2005, after a decade-long increase.

Gonorrhea cases in the St. Louis metro area reduced slightly last year, and rates of syphilis have remained low, according to the CDC report.

Stoner attributes high rates of sexually transmitted diseases in St. Louis to three main causes: a need for screening sites, the availability of treatment, and a lack of public information about different infections. For example, a person with chlamydia and gonorrhea may not show symptoms for many years.

“When caught early they can be cured, but left untreated they can cause complications,” Stoner said. “We really believe that screening is the way to go.”

There were 1,297.4 cases of chlamydia per 100,000 people in the city of St. Louis in 2013—the highest in the country, according to the latest report by the Centers for Disease Control and Prevention. Nationwide, chlamydia is most common in people between the ages of 20 and 24, but teenagers (ages 15-19) are the second-highest risk group.

The report also shows the city of St. Louis had the second-highest rate in the nation for gonorrhea infections, at 551.3 cases per 100,000—a full three times higher than the rate in St. Louis County.

In a release, the St. Louis City Health Department said the rankings were meaningless because the city of St. Louis is counted separately from its county, and was compared to cities that sit within larger counties with lower population densities. When counted as a metro area, St. Louis ranks much lower.

"Preliminary data suggest that for 2014 compared to our high year of 2011, chlamydia may be down as much as 23 percent and gonorrhea down as much as 33 percent," the release stated.