Health officials in St. Louis worry about a steep rise in sexually transmitted diseases among teenagers and young adults.

In the city of St. Louis, the number of chlamydia cases jumped from just over 3,200 in 2002 to more than 4,500 last year. Slightly more than 40 percent of those diagnosed were 15-to-19-years-old. In St. Louis County, the number of people diagnosed with chlamydia or gonorrhea rose from 4,800 in 2002 to over 7,000 last year. By far, the most cases were found in residents aged 15 to 24.

Another startling statistic: the two diseases accounted for roughly two-thirds of all communicable diseases reported in the county – more than cases of influenza or chicken pox.

Health officials are very worried about the rate of sexually transmitted diseases among blacks. In St. Louis, more than 90 percent of the chlamydia and gonorrhea cases reported is among the black population.