Human Papilloma Virus

HPV – Human Papilloma Virus

 

Cervical cancer is the second most common cancer in women aged 15-45 years of age. Half a million women world-wide develop cervical cancer each year, with approximately half of these dying as a result. Cervical cancer is predominantly caused by the Human Papilloma Virus (HPV).  Previously the only way to prevent cervical cancer was through well organized screening and early detection programmes using PAP smears. In 2006 a vaccine was licensed to protect against four of the HPV types that cause cervical cancer. Now a second vaccine protecting against two types of HPV has been introduced. These are the first 2 anti-cancer vaccines that have been manufactured.

 

There are approximately a 100 different types of HPVs and about 13 of them are known to infect the cervix and can lead to cervical cancer (WHO, 2007). HPV can also cause skin warts and skin lesions as well as genital warts. Certain types of HPV are called “high risk’ as they are associated with most cases of cervical cancer. “Low risk” types cause genital warts and low grade cervical abnormalities. Most women who have an HPV infection will not realize that they do as they will not have symptoms. It is believed that 90% of the time the HPV virus will be cleared by the body’s natural defense system within two years. If an infection lasts longer than 12 months however, there is an increased risk of persistent infection. HPV 16 and 18 are the two types of HPV that account for 70% of all cervical cancers in women worldwide. The rest of cervical cancers are due to other types of HPV that are not so common.

HPV is highly contagious - the most common, though certainly not the only, means of transmission is through sexual intercourse. The use of condoms will only prevent 50% of HPV infections (as HPV is a skin infection), however they will protect against other sexually transmitted infections, such as HIV and Hepatitis B, when used correctly.

It is estimated that most men and about 80% of women in the world will come into contact with HPV. However, only a small proportion of women will develop cervical pre-cancer.

Currently there are two vaccines that both follow a 3 injection schedule:

Name of Vaccine

Protects against

Schedule

Cervarix

HPV 16 & 18 (most common viruses associated with cervical cancer)

Month 0, 1, 6

Gardasil

HPV 16 & 18, 6 & 11(most common viruses associated with genital warts)

Month 0, 2, 6

If this schedule is not followed, it is crutial that all three doses are given within one year.

It has been recommended to give the vaccine to females before they become sexually active and potentially exposed to HPV. It is usually incorporated into childhood or school vaccination programs, i.e. 9 – 13 years, as most children will be included in the programme that way. Also children’s immuno-conversion to vaccines is stronger than older teenagers so the vaccine offers greater protection. However older woman should also be vaccinated. Although the official cut off of the FDA is 26 yrs, the vaccine remains useful at least until the age of 55yrs. It is however, not treatment and will not affect the course of any abnormal cells or HPV infection that may already be present in the cervix.

It is important to note that despite vaccination, screening for cervical cancer with PAP smears will still play an important role in preventing cervical cancer as the pre cancer state can be cured before it becomes cancer. However the vaccination has gone a step further towards eradicating cervical cancer.