1 Million STDs Are Diagnosed Every Day The World Health Organization has reported that 1 million cases of four STDs are diagnosed every single day. The four cases are chlamydia, gonorrhea, trichomoniasis and syphilis. The WHO reports that 1 in 25 people worldwide has at least one of these STDs. Melanie Taylor, lead study author, via CNN Over 376 million new cases are reported annually. STDs spread through unprotected vaginal, anal and oral intercourse. Untreated infections can lead to infertility in men and women.