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Epidemiology
Introduction
Human papillomavirus (HPV) is one of the most
common STDs. More than 30 types of HPV are sexually
transmitted and can infect the genital tract. Genital HPV
types are divided into two groups, based on their
association with cervical cancer. Infections with low-risk
types can cause genital warts and benign or low-grade
cervical cell changes (mild Pap test abnormalities) but are
not associated with cervical cancer. Infections with
high-risk types can cause low-grade cervical cell changes,
high-grade cervical cell changes that are precursors to
cancer (moderate to severe Pap test abnormalities), and, in
rare cases, cancers of the cervix, vulva, anus, and penis.
Most HPV infections, whether caused by low-risk or high-risk
types, are transient, asymptomatic,
and have no clinical consequences.
Information on the incidence and
prevalence of HPV infection
is incomplete because it is not a reportable infection in
any state (genital warts are reportable in a few states);
most infections are not diagnosed because they are
asymptomatic or subclinical, and have no clinical consequences; and most
studies estimating incidence and prevalence have been
performed in women, with little data about men.
Incidence
An estimated 6.2 million new cases of sexually
transmitted HPV occur in the U.S. each year.
Direct annual
medical costs for treating symptoms of genital HPV infection
in the United States are estimated at $1.6 billion. An
estimated 20 million people in the U.S. (15% of the
population) currently have a detectable genital HPV
infection.
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Estimated Annual Incidence of Selected STDs in the U.S.
, 2000 |
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Trichomoniasis
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7.4 million
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Human Papillomavirus (HPV)
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6.2 million
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Chlamydia
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2.8 million
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Herpes Simplex Virus (HSV) Type 2
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1.6 million
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Gonorrhea
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718,000
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Syphilis
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37,000
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Prevalence
It is estimated that at least 50% of sexually active men
and women acquire genital HPV infection at some point in
their lives. A recent estimate suggests that 80% of women
will have acquired genital HPV infection by age 50. An
estimated 9.2 million sexually active youth 15-24 years of
age are currently infected with genital HPV.
Transmission of Genital HPV
Transmission of genital HPV is predominantly associated
with sexual activity; viable HPV and microtrauma to
skin or mucous membranes are likely required. Transmission can
occur from asymptomatic and subclinical patients.
Infectiousness after treatment of warts or cervical cell
abnormalities is unknown.
Transmission by fomites has never been
documented.
Although rare, genital HPV infection with low-risk types can
be
transmitted from mother to baby during delivery and causes
respiratory tract warts in the baby, known as recurrent
respiratory papillomatosis (RRP). The preventive value of
cesarean delivery is unknown and, thus, should not be
performed solely to prevent transmission of genital HPV to
the newborn.
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