The sexually transmitted diseases, chlamydia and gonorrhea, are easy to cure but often go undiagnosed because they are mostly asymptomatic. Untreated, they can cause ectopic pregnancies, PID (pelvic inflammatory disease) and infertility. This study is the most comprehensive assessment to date of how widespread these diseases are among young Americans. In 2001-2002, the researchers interviewed a national, representative sample of 14,322 young adults between 18 and 26; about 88 percent of them provided a urine specimen that was screened for infection. More than 4 percent had chlamydia. The rate was slightly higher among women than men, and much higher among blacks than whites, and it was also relatively high among Native Americans and Latinos. Gonorrhea was less prevalent at 0.4 percent, and it, too, was significantly higher among blacks than whites. The authors found a much greater incidence of chlamydia than have studies that relied on information from clinics. They question whether current screening recommendations are adequate since they largely exclude men and are based on clinic data. They note that their findings are limited chiefly by the adequacy of the study sample and the diagnostic test used.