 After HPV, trichomoniasis and chlamydia are the most common STI diagnoses among 15- to 24-year-olds; combined, they account for slightly more than one third of diagnoses each year.Genital herpes and gonorrhea together account for about 12% of diagnoses.HIV, syphilis and hepatitis B account for less than 1% of diagnoses, however young people aged 13–24 accounted for about 21% of all new HIV diagnoses in the United States in 2011.