A 2008 study by the CDC found that one in four teen girls, or an estimated 3 million girls, has an STI. The study of 838 girls who participated in a 2003–04 government health survey found the highest overall prevalence among black girls; nearly half in the study were infected. This is compared with 20% among both white and Mexican-American teens. The same study found that, among those who were infected, 15% had more than one STI, and 20% of those who said they had only one sexual partner were infected.