Etiology of HPV HPV transmits by contact. Commonly, people assume it as an STD. However, sexual intercourse is not the only way of transmission. Vaginal, oral and anal sex and skin-to-skin contact transmits HPV from one partner to another. An HPV-infected mother can transmit the infection to her baby during delivery. In such case, the baby often develops HPV-related warts in the airway resulting in recurrent respiratory papillomatosis. HPV is site specific. The type of HPV that infects skin cells does not infect moist epithelium whereas the type which infects moist epithelium does not infect skin cells. In genital warts, 40 different types of HPV are found.