The majority of the nearly 200 known types of Human papillomavirus (HPV) cause no symptoms in most people. However, roughly 40 types of HPV — transmitted through skin to skin sexual contact — can manifest themselves in genital warts, and more seriously, can lead to cancers of the cervix, vulva, vagina and anus in women, or cancers of the anus and penis in men. Symptoms of HPV normally appear in the form a cauliflower like growths (i.e. warts) on the inside and the outside of a woman’s vagina.
Most HPV infections in young females are benign and don’t have long-term significance. 70% are gone in a single year and 90% eradicating within two years. But when infection persists—in 5% to 10% of infected women—there is the high risk of developing the cervical precancer, which can progress to invasive cervical cancer. This process can takes as long as 15–20 years though, providing many opportunities for detection and treatment of the pre-cancerous condition, often with high cure rates. HPV infection is a cause of nearly all cases of cervical cancer. However, most infections with HPV do not cause disease. Signs and symptoms may take weeks, months, and perhaps years to appear, with some symptoms never actually appearing.
Factors that may increase the risk of cervical cancer in women with HPV infection include smoking and multiple pregnancies. Having numerous sexual partners is also a risk factor for HPV. Using a condom may provide only limited protection.
Two HPV vaccines are currently on the market in the US: Gardasil and Cervarix. Both vaccines protect against two of the most common high risk HPV types (HPV-16 and HPV-18) These two types are the cause of most cervix and genital cancers. Public health officials in Australia, Canada, Europe, and the United States recommend vaccination of young women and girls as young as 9 years of age to prevent cervical cancer and genital warts. The vaccine will have the most impact if given before any sexually activity has occurred.
Worldwide, HPV is the most common sexually transmitted infection in adults.
For example, more than 80% of American women will have contracted at least one strain of HPV by age fifty. There are an estimated 470,000 new cases of cervical cancer that result in 233,000 deaths per year globally. In the United States, most of the approximately 11,000 cervical cancers found annually occur in women who have never had a Pap smear, or not had one in the previous five years.
The vaccine is not recommended for pregnant women, as there has been limited research looking at safety for them and their unborn babies. As of now, studies do suggest that the vaccine won’t cause health problems for pregnant women or their developing child. If a woman finds out she is pregnant after she’s started getting the vaccine series, she should wait until her pregnancy is over before finishing the series.
It is not yet known if the current vaccine is effective in boys or men, however vaccinating males could possibly have health benefits by preventing genital warts and rare cancers, such as penile and anal cancer. It is also possible that vaccinating males will have indirect health benefits for females. Studies are currently underway to see out if the vaccine works to prevent HPV infection in males. When more information is available, an HPV vaccine may be licensed and recommended for boys and men as well.