^ Weiss, Margaret D.; Wasdell, Michael B.; Bomben, Melissa M.; Rea, Kathleen J.; Freeman, Roger D.; Xue, H; Yang, H; Zhang, G; Shao, C (February 2006). "High Prevalence of Sexually Transmitted Diseases Among Men Who Have Sex With Men in Jiangsu Province, China". Sex Transm Dis. 33 (2): 118–123. doi:10.1097/01.olq.0000199763.14766.2b. PMID 16432484.
Unprotected receptive anal sex (with an HIV positive partner) is the sex act most likely to result in HIV transmission. Other infections that can be transmitted by unprotected anal sex are human papillomavirus (HPV) (which can increase risk of anal cancer); typhoid fever; amoebiasis; chlamydia; cryptosporidiosis; E. coli infections; giardiasis; gonorrhea; hepatitis A; hepatitis B; hepatitis C; herpes simplex; Kaposi's sarcoma-associated herpesvirus (HHV-8); lymphogranuloma venereum; Mycoplasma hominis; Mycoplasma genitalium; pubic lice; salmonellosis; shigella; syphilis; tuberculosis; and Ureaplasma urealyticum.
Reduce your risk of cutting or scratching your partner by trimming your nails. Long nails might tear the thin, delicate tissue of the anus, which could lead to bleeding. It also increases the risk of spreading bacteria that could cause infections. Be sure to wash your hands well and scrub under your nails after anal sex, too, especially before inserting them into the vagina or mouth.