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) 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 pre- malignant, 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