What is the difference between high-risk HPV and low-risk HPV?

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There are more than 50 types of human papillomavirus, or HPV, although some of them are far more common than others. Most people will only ever hear the names of the four most common types of the virus, and the numerical designations the variants are given may seem confusing - or even meaningless. That's why most doctors talk about the type of HPV someone has been infected with rather than the specific variant.

They break the types of virus down into the broad categories of high-risk and low-risk HPV.

High-Risk HPV

High-risk HPV types include HPV 16, 18, 31, 33, 35, 45, 52, 58 and 59. These types are also known as oncogenic HPV, because of their link to a variety of cancers - including cervical, penile, anal, and throat. However, it's important to know that not everyone who is infected with high-risk HPV will develop cancer. In fact, the majority of people infected with high-risk HPV will clear the infection on their own without ever having a problem.

Low-Risk HPV

Low-risk HPV types include HPV 6 and 11, as well as a number of less common variants. Low-risk types are also known as non-oncogenic HPV, as they are associated with more benign conditions such as genital warts. Infections with low-risk types of HPV are not generally associated with an increased risk of cervical and other cancers. Furthermore, as with high-risk HPV, most people with low-risk HPV will clear their infections within two years.

Vaccination to Prevent HPV

There are currently two commercially available HPV vaccines - Cervarix and Gardasil. Both vaccines protect against the two most common high-risk HPV types -- HPV 16 and HPV 18 -- and there is some data suggesting that their may be cross-protection against other high risk HPV types as well.

In addition, Gardasil also protects against the two types of HPV most commonly associated with genital warts -- HPV 6 and HPV 11.

What is the Real Risk of HPV?

HPV infection is associated with a number of potentially negative outcomes, but most people infected with HPV will never experience any consequences of that infection -- let alone serious consequences. That's why, despite the fact that most of the sexually active population will be infected with HPV at some point during their reproductive lives, many doctors don't consider HPV infection to be that big a deal. It's important to keep an eye out for persistent infections, infections that last two years or longer, but such infections are the exception rather than the rule.

Therefore, if you've been exposed to, or diagnosed with, HPV, don't panic. Talk to your doctor about what you need to do in terms of HPV testing and cancer screening, but avoid assuming the worst. There's a very good chance that everything will be just fine.

Sources:

Arbyn M, Tommasino M, Depuydt C, Dillner J. Are 20 human papillomavirus types causing cervical cancer? J Pathol. 2014 Dec;234(4):431-5

Bzhalava D, Eklund C, Dillner J. International standardization and classification of human papillomavirus types. Virology. 2015 Jan 8;476C:341-344.

Struyf F, Colau B, Wheeler CM, Naud P, Garland S, Quint W, Chow SN, Salmerón J, Lethinen M, Del Rosario-Raymundo MR, Paavonen J, Teixeira JC, Germar MJ, Peters K, Skinner R, Limson G, Castellsagué X, Poppe WA, Ramjattan B, Klein TD, Schwarz TF, Chatterjee A, Tjalma WA, Diaz-Mitoma F, Lewis DJ, Harper DM, Molijn A, van Doorn LJ, David MP, Dubin G; for the HPV PATRICIA Study Group. Efficacy of human papillomavirus (HPV)-16/18 AS04-adjuvanted vaccine against incident and persistent infection with non-vaccine oncogenic HPV types using an alternative multiplex type-specific PCR assay for HPV DNA: post hoc analysis from the PATRICIA randomized trial. Clin Vaccine Immunol. 2014 Dec 24. pii: CVI.00457-14.

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