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.
Thrush is caused by the Candida albicans fungus. This fungus is present in different parts of the body and kept under control by the body's immune system and other harmless bacteria. Thrush can develop when that subtle balance is disturbed.