From the Centers for Disease Control and Prevention website (here):

Sexually Transmitted Diseases (STDs) have been rising among gay and bisexual men, with increases in Syphilis being seen across the country. In 2014, gay, bisexual, and other men who have sex with men accounted for 83% of primary and secondary Syphilis cases where sex of sex partner was known in the United States. Gay, bisexual, and other men who have sex with men often get other STDs, including chlamydia and gonorrhea infections. HPV (Human papillomavirus), the most common STD in the United States, is also a concern for gay, bisexual, and other men who have sex with men. Some types of HPV can cause genital and anal warts and some can lead to the development of anal and oral cancers. Gay, bisexual, and other men who have sex with men are 17 times more likely to get anal cancer than heterosexual men.