HPV is a double-stranded DNA virus that infects epithelial cells. More than 100 strains of HPV have been identified to date. approximately 40 strains are known to infect the mucous membranes of the genital tract, and 15 of these strains cause cancer. types 16 and 18 HPV are the most common strains that can cause cervical cancer and are associated with 70% of cervical cancers worldwide. types 6 and 11 HPV are associated with 90% of genital warts. According to the ACS, approximately 11,000 women in the United States were diagnosed with cervical cancer in 2009. In the same year, approximately 4,000 women in the United States died from cervical cancer. Globally, cervical cancer is a growing problem due to the lack of screening and treatment programs for all women. Worldwide, 500,000 new cases of cervical cancer occur each year and more than 250,000 women die from cervical cancer. Cancers of the vulva, vagina, penis, anus, and a portion of the head and neck have also been linked to HPV infection.