Use a comma to separate nonessential elements from a sentence. More specifically, when a sentence includes information that is not crucial to the message or intent of the sentence, enclose it in or separate it by commas.
Genital warts are a sexually transmitted infection (STI) caused by certain strains of the human papillomavirus (HPV). These skin growths can cause pain, discomfort, and itching. They are especially dangerous for women because some types of HPV can also cause cancer of the cervix and vulva.
More than 40 types of HPV cause genital warts. Genital warts can be passed from person to person through intimate sexual contact (touching someone's genitals or having vaginal, oral, or anal sex). In some rare cases, genital warts are transmitted from a mother to her baby during childbirth.