Correlation is not causality. Tell us, are STD rates trending up in California as well?
Second, the study I referred to, published 2 months ago in the Californian Journal of Health Promotion --- the one reporting 1.1 million new cases of sexually-transmitted infections among young people in California in 2005 --- is certainly underatated. Study author Dr. Petra Jerman told Medical News Today that the statistics revealed an epidemic of which, like an iceberg, only a small part is visible.
The authors acknowledged that their figures are underestimated because of incomplete screening of sexually active young people, and failure to confirm the effectiveness of treatment through follow-up testing.
Moreover, their figures reflected infection rates for chlamydia, gonorrhea, HPV and HIV, while yours, unless I'm mistaken, are only for syphilis, by far the least common of the STI's.
I assume that if the full range of STI's are underreported in California, as Dr. Jerman says, they're even LESS accurately reportd in other states, many of which don't even have uniform county-by-county reporting requirements.
Here's a world map of adult HIV prevalence. I would hesitate to make any generalizations based on the map, but I will note one thing I don't see: any consistent correlation between countries with the lowest rates of HIV infection (green on the map) and a high prevalence of the type of "modern, comprehensive" sex education pical of Europe and the USA.