The human papilloma virus (HPV) is associated with the development of cervical cancer, genital warts and other cancers.  Although two HPV vaccines have been approved on the market: Gardasil in 2006, which protects against HPV-6 and HPV-11, and Cervarix in 2009, the vaccine applications are still limited to age barrier (WebMD, nd).  Gardasil is recommended as a routine vaccination for females aged 9-26 years old and for boys and men aged 11 to 21 while Cervarix, is recommended for use in females aged 10-25 years old. In the US, 20 million people are affected with HPV, and about 30 of the 100 HPV-types are transmitted sexually (Web MD, nd). Many epidemiological and experimental studies, indicated that 99% of cervical cancers contains HPV DNA, and four specific HPV types (6, 18, 31, and 45) cause at least 80% of diagnosed cervical cancers (Pagliusi, nd).

World-wide, the prevalence of HPV infection ranges between 9-13%, which accounts for 630 million infected individuals. An infected individual will develop HPV symptoms within three months, and 70% of genital HPV infections are subclinical, and never progress to disease (Pagliusi, nd).  In addition, most HPV infections regress spontaneously.

HPV-16 and HPV-18 causes 70% of cervical cancers, 80% of anal cancers, 60% of vaginal cancers, and 40% of vulvar cancers. These HPV strains also cause most oral cancer and some other rare genital cancers. On the other hand, HPV-6 and HPV-11 causes 90% of genital warts (WebMD, nd).

There are 100-plus types of other HPV virus.  The prevalence of infectious disease such as HPV can increase to a staggering number, which may create public health concern if appropriate screening and test programs are not in place.  Pap test (Pap smear) and HPV test are used to screen for HPV sequentially. Furthermore, HPV test, provides more information when Pap smear test is unclear (CDC, nd).  Due to the age barrier the HPV vaccines poses, people under the age 10 and people over the age of 25 years old are not immune from the virus.  Therefore, screening test should focus on the age groups outliers of the vaccines.   However, until all the 100-plus types of HPV are accurately characterized, the sensitivity, specificity, positive predictive value (PPV) or negative predictive value (NPV) of HPV screening may not be valid and reliable.  Most importantly, if the screening process is not reliable, the pre-clinical phase, clinical phase and clinical outcome may not be cost-effective (Gordis, 2009).

References

Center for Disease Control and prevention. (nd).  Human Papillomavirus (HPV): Screening. Retrieved from http://www.cdc.gov/hpv/screening.html.

Gordis, L. (2009).  Epidemiology (4th ed.). Philadelphia, PA: Saunders/Elsevier.

Pagliusi, S (nd).Vaccines against Human Papillomavirus.  Retrieved from http://www.who.int/vaccines/en/hpvrd.shtml.

Web MD. (nd).  HPV Vaccines.  Retrieved from http://www.webmd.com/sexual- conditions/hpv-genital-warts/hpv-vaccines-human-papillomavirus.