Human papillomaviruses (HPV) are a group of common viruses spread through skin to skin contact. Some are sexually transmitted and can cause causing genital warts, and a range of types of cancer. There are more than 150 types of HPV, at least 14 of these are high-risk types linked to cancer.
The HPV types that cause warts on the skin and genital region differ from the types that cause cancers. HPV types 16 and 18 are responsible for around 7 out of 10 cervical cancers while types 6 and 11 cause approximately 9 out of 10 cases of genital warts and warty growths in the throat. Other HPV types, HPV-31, 33, 45, 52, 58, are also linked to cervical cancer.
Without immunisation, around 80% of adults will have a HPV infection at some time in their life. Most infections resolve within two years. However, in about 2 in 100 people infection remains after five years. Persistent infection can cause abnormal changes to cells in the cervix, penis, genital, anal and throat tissues in women and men, which can lead to cancer if left untreated.
HPV is very contagious and can be spread through skin to skin contact, as well as sexual intercourse. Virus can be spread through hand-genital contact, oral sex (mouth-genital contact) and from infected mothers to their newborn baby during the birth process.
As most people do not know when they are infected, an infected person can unknowingly spread the virus to others.
Generally people have no symptoms of HPV infection, except as genital warts. It is therefore important for all women to undergo regular cervical smear tests, whether they have been vaccinated or not.
If left undetected HPV can lead to cancer, including cervical cancer, anal cancer and cancers affecting the mouth, throat, vulva, vagina and penis. It can take 20 years or longer from infection to the development of cancer.
Symptoms of genital warts include raised or flat bumps in the genital areas described as soft, moist or flesh-coloured and often taking a cauliflower shape. These can appear in the weeks or months following infection. In women, warts can appear on the areas inside or surrounding the vagina, cervix and anus. In men, warts can appear on the scrotum, penis and inside or surrounding the anus.
Symptoms of cervical cancer include bleeding or spotting between menstrual periods, bleeding or spotting after sexual intercourse, bleeding or spotting after menopause, unusual vaginal discharge, persistent pain in the pelvis, or pain during sexual intercourse.
Treatments for genital warts depend on the size, location and severity of the warts, and include creams and solutions that are applied directly onto the skin or infected area. Other types of treatment include burning, freezing, laser or surgical removal of warts. These treatments cannot prevent the genital warts from reappearing.
There is no treatment for persistent HPV infection itself, however, abnormal or precancerous cells caused by HPV can be treated. Treatment varies depending on the severity and location of the cell changes, and can range from burning, freezing or local removal to radiotherapy, chemotherapy and major surgery.
Most people with HPV infection will clear the virus without any complications.
About quarter of people with HPV infection will develop genital warts which can be uncomfortable and embarrassing.
As described, some types of HPV cause cancers. Early detection of cancer is very important. Cancer can spread to the bladder, intestines, lungs and liver and may ultimately be fatal.
Other risk factors for HPV-related cancer include:
HPV vaccine is highly effective in preventing infection with the most common high risk HPV types. The vaccine protects against HPV 6 and 11, which cause genital warts, and seven high-risk types, namely, HPV-16, 18, 31, 33, 45, 52 and 58, which are associated with oral and genital cancers, including cervical cancer. Since the vaccine became available in New Zealand in 2008, the incidence of genital warts has decreased by 75%..
The best time for HPV immunisation is prior to any sexual activity. The vaccine produces a better immune response in preteens than older teens.
HPV vaccine is recommended and funded for girls and boys aged 9 to under 27 years. A school-based vaccination programme is available in most areas of New Zealand.
The vaccine is also recommended, but not funded, for women aged up to 45 years to help to prevent reinfection with HPV following colposcopy treatment for cervical abnormalities. It is also recommended, but not funded for males and females aged 27 years or older who have had little exposure to HPV in the past and are now likely to be exposed, are men who have sex with men or are HIV-positive.
Use of condoms during sexual intercourse is recommended, but cannot completely prevent the spread of HPV.
Having a cervical smear tests every three years, if no abnormalities are present, is the best way to detect changes to the cells of the cervix that may later lead to cancer. Regular cervical smears can reduce a woman’s risk of developing cancer by 90%. Women who have had an HPV vaccine should still undergo cervical screening to detect the rarer HPV types not covered by the vaccine.