When More Money = More Syphilis - Freakonomics Blog - NYTimes.com

"Over the last decade, the number of syphilis cases in China increased tenfold, according to this Associated Press report, because more migrant workers have been able to afford to hire prostitutes. The A.P. further reports that the “stigma and perceived high cost of visiting sexual health clinics” in China is hampering prevention and treatment efforts. In the U.S., meanwhile, police informants are paid well to become johns."