HPV - or human papilloma virus - is commonly called the wart virus. More than 100 types of HPV have been identified, and they can cause problems ranging from warts on hands and feet to genital warts and precancerous changes in the cells of the cervix.
Genital HPV
From your question, I suspect you're referring to genital HPV, so I'll focus on these types of infection, which are transmitted by sexual contact.
About 40 types of HPV can cause genital disease, the most important being HPV types 6, 11, 16, and 18 (these type numbers are particularly important because new vaccines against HPV only protect against certain types).
It's important to bear in mind that the types of HPV that cause warts are generally different to those linked to cervical cancer. HPV 6 and 11 are most commonly associated with genital warts, while HPV 16 and 18 are found in most cases of cervical cancer. These HPV infections are also linked to cancer of the penis and anus in men.
HPV is now believed to be the most common sexually transmitted infection, and it’s thought that at least 75 per cent of people of reproductive age have been infected this way at some point. But many of these people will never have had warts, cancer or any other symptoms - laboratory tests are the only clue that infection once occurred.
But among sexually active young adults, up to 46 per cent currently have the virus, so there's a high risk of catching it if you have unprotected sex.
The virus is passed on very easily. It's important to remember the wart virus is most often spread during intimate contact, when infected skin rubs against uninfected skin, rather than being spread by semen, vaginal secretions or blood.
As the wart virus is found on a wide area of skin around the genitals, condoms don't provide enough protection to guarantee against infection - they help to reduce the risk, but skin-on-skin contact may be enough to lead to infection.
To complicate things further, the affected person may show no visible signs of having the virus and it's impossible to know whether your partner could be infecting you. Many people pass on the virus for years without any visible warts themselves - only one person in 100 with HPV will show any warts.
The virus may never be eliminated
If you have warts, most doctors now suggest that only the large visible ones are treated. This is a cosmetic exercise and won't change your ability to pass on the virus.
Most visible HPV infections disappear without treatment, usually after several months. Treatment aims not to eliminate the virus but to overcome it, and the most important factor is your immune system.
You may carry the virus for the rest of your life, passing it on any time you have visible warts - and possibly even when there's no detectable infection. But if it's been many years since you last had warts, your risk of spreading the virus is low.
If your partner has never had warts, you should use condoms and a spermicide, although in long-term relationships some couples accept the risk that the partner may get infected. Recurrences of warts are thought to be caused by reactivation of the HPV, not reinfection from a sexual partner.
HPV doesn't interfere with having children
Having HPV shouldn't get in the way of having children or enjoying any other aspect of normal life. Warts do tend to grow larger during pregnancy, probably due to the increasing levels of progesterone, and very occasionally cause practical problems during delivery. But they shouldn't be treated without consulting your doctor, as some treatments may harm the unborn child.
The link to cervical cancer
Other types of HPV found widely among the population are known to be linked to cervical cancer. Almost every woman who develops cervical cancer will test positive for HPV, but this doesn't mean HPV always leads to it. Rather, HPV can result in precancerous changes in the cervix (known as dysplasia).
Even if these mild changes do occur, in up to 70 per cent of cases the cervical cells return to normal without treatment.
In some cases though, mild dysplasia can progress to more significant cancer, and two particular factors can increase the risk:
- Smoking
- Nutritional deficiencies
Women with mild dysplasia should give up smoking and encourage their partners to do the same, because the harmful chemicals can be passed on during sex.
They should also eat five servings of fruit and vegetables a day or take a daily multivitamin that contains antioxidants such as vitamin E and beta-carotene, and have regular cervical smears.
Vaccine against HPV
A vaccine against some of the more common types of HPV linked to cervical cancer (and to some extent to genital warts) is licensed in the UK. This will help protect women from cervical cancer and may be added to the standard immunisation schedule to protect young women before they become sexually active.
There is also a strong argument that the vaccine should be given to young men, too, because as well as protecting against the rarer cancers of the anus and penis, it provides a degree of protection to both sexes against genital warts which, while not life threatening, can be a source of huge misery.
This article was last medically reviewed by Dr Trisha Macnair in May 2008
