Download Chapter 29 Human Papilloma Virus Infection and Immunity

Chapter 29
Human Papilloma Virus
Infection and Immunity
HPV Infection
• The most prevalent sexually-transmitted
infection in the U.S. with 6.2 million cases; over
20 million worldwide
• HPV infection is directly associated with a higher
risk of cervical cancer
• Cervical cancer is usually detected through the
Pap smear
• Most infections are self-limited and disappear
Human Papilloma Virus (HPV)
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DNA virus that infect epithelial cells
More than 100 strains
Persistent and oncogenic
Infects the epithelium of the cervix, vagina,
vulva, anus, penis, mouth, and sinus
• About 30 strains have the potential to
transform epithelial cells into premalignant, and ultimately malignant, cells
HPV Infection
• Evades immune system destruction by:
- Downregulating the cellular immune
response
- No release of inflammatory cytokines
- Poor response of antibody
• End result is the establishment of a
persistent asymptomatic infection that may
lead to pre-malignant cellular reactions
Diagnosis of Infection
• Transmission is typically by sexual
intercourse
• Usually diagnosed by the detection of an
abnormal Pap smear indicating chronic
infection
• Asymptomatic infection is the common;
occasionally, genital warts
Cervical Cancer
• Over 500,000 cases diagnosed annually
worldwide with 260,00 deaths;in the US,
9,710 cases and 3,700 deaths
• Cervical cancer is the second leading
cause of death among women worldwide
• Prevention of cervical cancer can be
accomplished with the use of an effective
HPV vaccine
The HPV Vaccine
• Quadrivalent vaccine developed by Merck
directed against the strains that cause 90% of
cervical cancer
• Vaccine effectiveness is 90-95% in most
population trials; data is only from five years of
experience
• Need for regular use of Pap smear continues as
protection exists for only four strains
Vaccine Recommendations
• ACIP recommends the vaccine for girls and
women ages 9 through 26; ideally, prior to the
onset of sexual activity
• Administered in three doses over six months
• Cost issues - $360 per three dose regimen
• Covered by most form of insurance;special
programs through Medicaid and SCHIP
• Vaccines for other HPV strains in development
Vaccine Acceptability
• Evidence suggests high degree of
acceptability by physicians, gynecologists,
patients, and parents
• Issue/concern on the part of some parents
that use will increase sexual activity
• Issue of mandating vaccine in the states;
no state currently has such a statute