Human Papillomavirus

DESCRIPTION

Human papillomaviruses (HPV) are double-stranded DNA viruses, members of the Papillomaviridae family, which cause warts of the skin and mucous membranes.
- Cutaneous viruses cause skin, plantar, flat, and thread-like warts.
- HPV types 6 and 11 cause exophytic venereal warts or condylomata acuminata and also can cause squamous cell carcinoma of the external genitalia.
- Virus types 16, 18, 31, 33, and 35 typically cause subclinical infection in the anogenital region and have been associated with intraepithelial genital carcinomas.
- 70% of cervical cancers are attributed to virus types 16 and 18.
- HPV type 16 causes the majority of other HPV-related cancers such as anogenital cancer (anal, penile, vaginal) and oropharyngeal cancers.
HPV can also cause recurrent respiratory papillomatosis (RRP) in infants and young children. RRP primarily impacts the larynx but can also cause lesions anywhere along the respiratory tract.
Increasing evidence that HPV may play a role in squamous cell carcinomas of the oropharynx

General
- Nongenital hand and foot warts are common among school-aged children.
  - Widespread cutaneous lesions can occur in those with compromised cellular immunity.
- Incubation period for symptomatic infection ranges from 3 months to several years.
- Most infections are asymptomatic.
- HPV is the most common viral sexually transmitted infection (STI).
- Genital warts and HPV infection are diseases of young adults who are 20 to 24 years of age.
- Cervical cancer is the 3rd most common female cancer worldwide.
Genital HPV
- Peak prevalence among women 18 to 24 years of age
- At least 40% of sexually active adolescents are infected with HPV.
- <1% of adolescents develop genital warts.
- >33,000 cases of HPV-attributable cancers annually in the United States
- 500,000 new cases of cervical cancer diagnosed each year internationally
- HPV accounts for 90% of all cervical cancers; 70% of oropharyngeal cancers; and most vulvar, vaginal, penile, and anal cancers.
RRP
- RRP impacts 4.5 per 100,000 children, mostly those aged 2 to 3 years.
- 67% of children with RRP are born to mothers who had condyloma during pregnancy.

Infants
- Primarily vertical transmission at birth
Adolescents
- Behavioral risks, including young age at first coitus, multiple partners, cigarette use, and having older male partners
- Biologic risk in adolescent girls secondary to cervical anatomy

9-valent HPV vaccine (HPV9 [types 6, 11, 16, 18, 31, 33, 45, 52, and 58]) is licensed by the U.S. Food and Drug Administration (FDA) for use in females and males ages 9 through 45 years.
- The American Academy of Pediatrics and advisory committee on immunizations of the Centers for Disease Control and Prevention (CDC) recommend vaccination of females and males between 9 and 12 years of age.
- 2 doses given 6 to 12 months apart are recommended when the vaccine is initiated prior to the 15th birthday, whereas 3 doses (0, 1 to 2 months, 6 months) are recommended when the series is initiated on or after the 15th birthday.
Condom use may diminish transmission.
Examine partners; treat those who are infected.
Pap (Papanicolaou) smear in adult women to assess for cervical dysplasia

Transmission
- Primarily through sexual contact
- Can also be acquired during the birth process through vertical transmission
- Transmission from nongenital sites is rare.
The incubation period is variable and ranges from 3 months to several years.
The virus is trophic for epithelial cells and infects the basal layer of actively dividing cells.
Infection results in koilocytosis and nuclear atypia. Genital infections may progress to severe dysplasia and carcinoma in situ (CIS).
Spontaneous regression of clinical disease occurs in 90% of low-risk types and 75% of high-risk types.
Recurrence is common.