Human Papilloma Virus (HPV) Overview

Papillomaviruses are a group of DNA-based viruses which affect the skin and mucous membranes of a wide variety of animals. There have been detected more than 100 types of Human Papillomaviruses and it is estimated that approximately 80 % of the population is infected with a strain of HPV at some point in their life.

HPV strains or types are divided into two categories. The first ones, the "low-risk" HPV strains that can cause benign skin warts or papillomas, are transmitted through the environment or by skin-to-skin contact. A separate group of about 30 HPV strains are sexually transmitted. Some of them can cause genital warts (such as types 6 and 11), others don't have any noticeable symptoms. Among the sexually transmitted HPV strains, there is a group so-called "high-risk" HPVs (including types 16 and 18) which can lead to the development of cancer of the cervix, vulva, vagina, anus, or penis.

In the United States the number of patients identified with HPV disease has increased markedly during the past 20 years because of heightened awareness of the various manifestations of HPV disease and because of increased use of HPV DNA testing. Approximately 7-10% of the population has nongenital cutaneous warts.

Approximately 20 million people are currently infected with HPV.The worldwide prevalence of HPV in cervical cancer is 95-99.7% and in anal cancer is 88%.

The incidence of genital HPV infection increases at the age when people begin to engage in sexual activity (see figure). Most of the genital HPVs don't have any noticeable symptoms and are fought against and cleared by the immune system in a couple of months. Nevertheless, in some cases, the immune system may fail to bring the infection under control. Lingering infection with "high-risk" HPV types, such as HPVs 16, 18, 31 and 45, can cause cervical cancer or other types of cancer. HPV types 16 and 18 are together responsible for over 70% of cervical cancer cases (Baseman and Koutsky, 2005; Cohen, 2005). Type 16 causes 41 to 54% of cervical cancers (Noel et al., 2001; Baseman and Koutsky, 2005) and accounts for an even greater majority of HPV-induced vaginal/vulvar cancers (Edwards et al., 2005), penile cancers, anal cancers and head and neck cancers (Bolt et al., 2005).

SIGNS AND SYMPTOMS

"Low risk" HPV types usually cause no symptoms at all or only one: genital warts.

Genital warts (also called condylomata acuminata or venereal warts) are usually soft, moist, pink, or flesh-coloured swellings that appear usually in the genital area. They can be raised or flat, single or multiple, small or large, and they sometimes look like cauliflower florets. In women the warts occur on the outside and inside of the vagina, on the opening (cervix) to the womb (uterus), or around the anus. In men the symptoms of the disease may be less obvious. When present, they usually are seen on the tip of the penis. They can also be found on the shaft of the penis, on the scrotum, or around the anus.After sexual contact with an infected person, warts may appear within weeks or months, or not at all. Genital warts can rarely develop in the mouth or through of a person who has had oral sex with an infected person.

Genital warts are very contagious. If you have an active outbreak of genital warts, it is best to refrain from any sexual activity until the warts have been treated.

It is very important to remember that HPV strains that can cause genital warts are NOT the same ones that cause cervical cancer!
TREATMENT

Currently, there is no cure for HPV infection. In most cases the immune system manages to clear the infection. The treatments available are directed to the effects of HPV on the skin or the mucous membrane. The treatment varies depending on several factors such as the size and location of your genital warts. Some of the medicines used to treat genital warts are: Imiquimod (an immune response modifier), Interferon alfa (cytokine), Podofilox (an antimitotic drug), Podophyllin (resin derived from the Mayapple), 5-Fluorouracil (antimetabolite interferes), Keratolytics (TCA and BCA).
If the warts are small they may be removed by freezing (cryosurgery), burning (electrocautery) or laser treatment. Bigger ones that have not responded to treatment can be removed by surgery.

COMPLICATIONS

Approximately 10 of the 30 identified genital HPV types (including types 16, 18, 31 and 45) can lead, in rare cases, to development of cervical cancer as well as anal cancer, vulvar cancer, head and neck cancers, and penile cancer.

Cervical cancer is the second most common type of cancer to affect women. However not all strains of genital HPV can cause cervical cancer. The ones that cause genital warts are extremely rare associated with this type of cancer.

Women who have genital warts during pregnancy may pass the warts to the child if they have an active outbreak, especially during a vaginal birth. HPV then develops in the child's throat and it can be life threatening.

PREVENTION

On June 8, 2006, the FDA approved Gardasil, a prophylactic HPV vaccine which is marketed by Merck. This vaccine was shown to be effective against initial infection with HPV types 16 and 18 (some of the HPV strains responsible for cervical cancer).

People with a greater number of sexual partners are more exposed to HPV infections. A way to prevent becoming infected with HPV is to reduce the number of sexual partners. Recent studies have shown that the condom offers little protection against this sexually transmitted disease. There are however some momentary solutions like topical microbicides or some sexual lubricant brands that use a gelling agent called carrageenan.

A way of preventing cervical cancer is to regularly have a Papanicolaou screening, colloquially known as "Pap" smear testing. This can also help prevent anal cancer. Also, it has been scientifically proved that tobacco smoking increases the risk of developing invasive cervical cancer and other HPV-induced cancer types. Smoking decreases the ability to absorb folic acid (used to treat cervical dysplasia, a symptom of HPV infection).