Human Papillomavirus

Definition and Epidemiology

Human Papillomavirus (HPV) is the most common sexually transmitted infection in the United States, with an estimated 6.2 million new infections each year in the United States. It is transfered by close skin to skin physical contact involving infected areas, including nongenital areas. 

There are more than 100 strains of HPV known, and they are sorted into high and low risk groups by their link to cancers. 

 

Infection

Among children, the most common presentation of HPV infection is of cutaneous infection in the form of a wart. Nongenital, HPV-associated warts occur in 10 percent of children, with peak incidence between the ages of 12 and 16. They can occur anywhere on the skin. 

Genital warts also occur in pediatric patients - peak prevalence in persons between the ages of 17 and 33. It is estimated that up to 80 percent of sexually active adults will be infected with at least one strain of HPV before the age of 50, though many of these infections are cleared. 

Infection of the respiratory mucosa, especially with HPV types 6 and 11, often occurs in young children and infants who were exposed to the virus through maternal infection. This is referred to as recurrent respiratory papillomatosis, and is decreasing in incidence as a result of the quadravalent vaccine. 

 

Link to Cancer

HPV has been extensively linked to cervical cancer, with over 500,000 cases worldwide a year. It has also been linked to vulvar, penile, and orophayngeal cancers. Multiple proteins created by the virus, most notably E6 and E7, which work in concert to immortilize epithelial cells. 

Several strains of the virus have an especially high associated with carcinomas. HPV 16 has been implicated in approximately 50 percent of cervical carinoma and HPV 18 has been associated with an additional 20 percent. 

Patients with primary and secondary immunodeficiencies are more prone to contracting associated malignancies, presumably due to their inability to clear the virus and associated carcinogenic proteins from their tissues. 

 

Vaccine

There are two types of HPV vaccines currently, both of which cover for strains 16 and 18, associated with 70% of cervical cancers. The quadrivalent vaccines also covers strains 6 and 10, associated with many childhood cutaneous warts and with respiratory papillomatosis

The AAP recomments vaccination for both boys and girls - with the first dose of three typically given at 11-12. For older patients, the vaccine is recommended for men up to 21 and women up to 26 years of age. 

 

References

Allen, Angel L., and Elaine C. Siegfried. "What’s new in human papillomavirus infection." Current opinion in pediatrics 12, no. 4 (2000): 365-369.

Charo, R. Alta. "Politics, parents, and prophylaxis—mandating HPV vaccination in the United States." New England Journal of Medicine 356, no. 19 (2007): 1905-1908.

Kim, Jane J., and Sue J. Goldie. "Health and economic implications of HPV vaccination in the United States." New England Journal of Medicine 359, no. 8 (2008): 821-832.

Steinbrook, Robert. "The potential of human papillomavirus vaccines." New England Journal of Medicine 354, no. 11 (2006): 1109-1112.