Human papillomaviruses (HPV) are common sexually transmitted viruses that can cause many types of cancer and other illnesses like genital warts. HPV can spread through skin to skin contact as well as sexual intercourse.
A brief history
There are more than 100 types of HPV, at least 13 of those are types known to cause cancer. Types 16 and 18 are responsible for around 70% of all cervical cancers. The HPV types that cause warts are different from the types that cause cancers. Types 6 and 11 cause approximately 90% of genital warts and are also known to cause respiratory papillomatosis (warty growths on the throat or vocal cords).
Three years after becoming sexually active around two thirds of women have been exposed to HPV (regardless of the number of sexual partners). Most infections resolve without any problems within two years. However, about 2% of infections are still present after five years. Persistent infection can cause abnormal cervical cell changes and if not diagnosed or treated can lead to cancer.
A vaccine has been available since 2006 in the US, and 2008 in New Zealand, which protects against strains 6, 11, 16, and 18.
There is no current information in New Zealand to show the percentage of people infected with HPV.
In a study of more than 2,000 women in the Wellington area, over a 9 month period between 1989-1990, 10.9% tested positive for HPV.
Every year in New Zealand around 160 women are diagnosed with cervical cancer and around 60 die from the disease. Many other women have abnormalities in the cells of their cervix which are detected by cervical screening. These require invasive treatment to prevent the development of cancer. In New Zealand cervical cancer is the third most common cause of cancer in women aged 25-44 years. There are significant disparities with rates 2-3 fold higher for Māori.
Some HPV types cause warts but do not lead to cancers. Other HPV types cause no obvious infection at the time, but can persist in cells of the genital tract.
If left undetected, HPV can lead to cervical cancer as well as other cancers affecting the mouth, throat, vulva, vagina, cervix, penis and anus. It takes usually about 10-20 years 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 vulva, areas inside or surrounding the vagina, cervix and anus. In men, warts can appear on the scrotum, penis and area 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 menstrual periods have stopped (after menopause), unusual discharge from your vagina, persistent pain in your pelvis, or pain during sexual intercourse.
Individuals can be infected with HPV without showing any signs or symptoms. For this reason, it is important for women to undergo regular Papanicolaou (Pap) cervical smear tests (every three years if no abnormalities are present).
How do you get it?
HPV is very contagious and sexual intercourse is not the only way to spread the virus. The virus can be spread through skin to skin (hand-genital) contact, oral sex (mouth-genital contact) and from infected mothers to their newborn baby during the birth process.
Most HPV infections do not show any symptoms so most people do not know when they are infected. An infected person can still spread the virus to others even if there are no signs or symptoms of HPV infection.
What are the risks?
Many people with HPV infection will clear the virus without any complications.
- About 25% of people with HPV infection will develop genital warts which can be uncomfortable and embarrassing.
- Some types of HPV cause cancers including cancers of the mouth, throat, vulva, vagina, cervix, penis and anus.
- Cervical cancer can spread to the bladder, intestines, lungs and liver and is ultimately fatal. Early detection is very important.
Who is the most at risk?
HPV is very common and most men and women will be infected at some point in their lives.
- Individuals with multiple sexual partners are at higher risk for HPV.
- In New Zealand, women over 40 years of age, and women who are Māori or Pacific are at higher risk for cervical cancer if they are infected with HPV.
- Māori women are almost twice as likely to get cervical cancer and almost three times as likely to die from it compared to non-Māori women.
- Women who smoke or take a birth control pill are at higher risk for cervical cancer if they are infected with HPV.
- Additional risk factors include: early start of sexual activity, multiple sexual partners, women who don’t participate in regular cervical screening and smoking.
- Having regular cervical smears can reduce a woman’s risk of developing cancer by 90%.
Treating the symptoms
There is no treatment for persistent HPV infection itself, however, there is treatment for abnormal or precancerous cervical cells caused by HPV and for genital warts. Treatment for abnormal, precancerous or cancerous cervical cells vary depending on the severity of the cell changes and include causterisation (buring), laser surgery, cone biopsy or loop excision, hysterectomy, radiotherapy and chemotherapy.
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.
Preventing the disease from spreading
Use of condoms is recommended but cannot completely prevent the spread of HPV.
Having a Papanicolaou (Pap) 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.
Immunisation with the HPV vaccine is highly effective in preventing infection with four of the most common HPV types.
|Risk of disease vs. vaccine side effects
||Effects of disease
||Side effects of vaccine
Human papillomaviruses (HPV) are common sexually transmitted viruses that can cause many types of cancer and other illnesses including genital warts and respiratory papillomatosis.
- Unsightly genital warts.
- Persistent infection can cause cancers of the mouth, throat, vulva, vagina, cervix, penis and anus.
- Invasive treatment for pre-cancerous lesions. Some of which increase risk of premature birth in subsequent pregnancies.
Common side effects
- Mild to moderate pain and inflammation at injection site.
Uncommon side effects
- Severe pain and swelling at injection site (less than 3 in 100 doses).
- Mild to moderate fever (less than 1 in 100 doses).
Rare/very rare side effects
- Anaphylaxis (3.2 in one million doses).
Human papillomaviruses (HPV) are a family of sexually transmitted viruses that cause cutaneous and genital warts and some cancers, most notably cervical cancer. HPV is the most common sexually transmitted infection (STI), it is easy transmissible, and it affects most men and women at some point in their lives. Many people clear HPV infections within 6-24 months, but certain strains can develop into genital warts or cancer. Of the 100 types of HPV, at least 13 are oncogenic.
HPV is present in the biopsies of more than 99% of cervical cancer specimens. Malignant progression is thought to be due to the direct action of two viral oncogenes E6 and E7, which inactivate two tumour suppressor genes. The oncogenes also cause genetic instability, which subsequently leads to dysplasia.
As well as cervical cancer HPV can cause oropharyngeal cancer (mouth and throat), cancer of the vulva, vagina, penis and anus.
Recurrent respiratory papillomatosis (RRP) is caused by HPV infection of the respiratory tract. It is a rare disease. It is usually benign but papillomas can sometimes block the respiratory tract, and in a few cases can become cancerous. The majority of cases occur in children, probably contracted from the mother during birth (this is called vertical transmission of the virus). RRP is most often caused by HPV types 6 and 11.
Double helix DNA viruses that infect skin or mucosal cells.
Clinical signs, symptoms and complications
Around 98% of infections resolve with no problems. About 2%, however, are still present after five years.
Presentation can vary according to type, of which there are more than 100, for example:
- Types 2 and 7 - common warts
- Types 1, 2, 4 and 63 - plantar warts
- Types 6, 11, 42, 44 and others - anogenital warts
- Types 6, 7, 11 and 16 - oral papillomas (non-cancerous growth)
- Types 6 and 11- throat papillomatosis
- Types 16 and 18 - most common types causing cervical, genital and anal cancers
- Type 16 - oropharyngeal (mouth and throat) cancers
“Low-risk” types of HPV cause benign warts and verrucae.
Low-grade cervical dysplasias identified in Papanicolaou (Pap) cervical smear tests indicate productive HPV infection; most resolve spontaneously, probably the result of cell-mediated immune responses. A small percentage progress to cancer.
Cervical intraepithelial neoplasia (CIN) is another method of signifying atypical cellular findings on a Pap smear, which commonly is HPV caused.
CIN is categorised into CIN 1, 2, or 3, depending on the severity of the abnormality and the thickness of the abnormal cell layer.
“High-risk” type 16 is associated with approximately 50% of cervical cancers and type 18 another 20%.
HPV causes over 99% of cervical cancers, 90% of anal cancers, 40% of external genitalia cancers, 12% of oropharyngeal cancers, and at least 3% of oral cancers.
HPV types 6 and 11 cause about 90% of external warts in the anogenital area.
Penile/perineal/perianal intraepithelial neoplasia (PIN), atypical cellular findings in males, are categorised into PIN 1, 2, or 3, depending on the severity of the abnormality. These are precursor states for penile/perineal/perianal cancer.
Method of transmission
HPV is sexually transmitted and highly infectious, yet sexual intercourse is not required for transmission.
Hand-genital, oral-genital contact and close skin-to-skin genital contact can also spread HPV.
Vertical transmission, or transmission from infected mother to newborn during birth is possible.
HPV can also be caught from contaminated clothes and objects, but this route is uncommon.
Public health significance
All sexually active people are susceptible to HPV infection.
- By three years post the onset of sexual activity, up to two thirds of women have been asymptomatically infected.
- Most people, male and female, will have had a genital HPV infection after 5 years of sexual activity.
- Genital warts are not usually fatal but cause significant morbidity and substantial health care costs.
- Ongoing infection, usually over many years can lead to cancer, although shorter time periods are also seen. Cervical cancer generally affects younger women in comparison to other cancers.
- In 2008 it was estimated that worldwide there were 530,200 cases and 275,000 deaths annually from cervical cancer.
- The current method of cervical cancer prevention worldwide involves identification of pre-malignant lesions by regular Papanicolaou (Pap) cervical smear tests.
New Zealand epidemiology
In 2004 there were 3822 new diagnoses of genital warts in males and females in sexual health clinics; population rates cannot be calculated. The age group most affected by genital warts is young adults aged 15−24 years. The number of new cases seen has increased over time, although some of the increase may represent changes in presentation at clinics rather than a change in incidence.
In considering options for timing an HPV vaccine for the immunisation schedule in New Zealand, it is useful to consider the results of the 2001 Youth Health Survey, which provides information on sexual behaviours. Among secondary school students in years 9 to 13, 17 percent of students aged 13 years reported they had had sexual intercourse, 33 percent of those aged 15 years, and 49 percent of students aged 17 years.
An Auckland study of 513 cervical swabs, mainly from women attending colposcopy clinics, found that 221 specimens (43 percent) were positive for HPV. Twenty-two different types of HPV were detected, and 141 were oncogenic types, representing 14 of the 18 known oncogenic types. Types 16, 18, and 31 were the most common detected, representing 39 percent, 10 and 10 percent of the oncogenic types found, respectively. The other 11 oncogenic HPV types ranged in prevalence from 7.4 to 0.6 percent.
New Zealand’s National Cervical Screening Programme, administered by the National Screening Unit of the Ministry of Health, became operational in 1991 and now achieves over 70 percent coverage of eligible women (ie, the 20–69 year age range). Over the past 10 years cervical screening has led to a 40 percent reduction in the incidence of invasive cervical cancer. However, incidence remains approximately twice as high among Mäori than among non Mäori women. Over the same period, mortality from cervical cancer has fallen about 60 percent. Again, ethnic inequalities remain, with mortality among Mäori still approximately 4 times that of non Mäori.
Both cervical cancer incidence and mortality have fallen dramatically in New Zealand (as in other developed countries) over the last decade, due to cervical screening however approx 160 New Zealand women are diagnosed with cervical cancer each year and on average 60 women die of the disease each year.
Condom use is recommended but cannot completely prevent HPV transmission as other infected areas of skin may be exposed.
Regular Papanicolaou (Pap) cervical smear tests (every 3 years) are recommended to detect any abnormalities around the cervix caused by HPV infection.
Gardasil® is the only HPV vaccine currently available in New Zealand which protects against genital warts strains (6 and 11) and cervical cancer strains (16 and 18).
A primary course of vaccine is recommended and funded for:
- Eligible girls* from 9 years to under 20 years of age with their family doctor or at school in year 8 with the public health nurses.
- HIV positive individuals aged 9 years to under 26 years of age.
- Individuals who are post-haematopoeitic stem cell transplantation.
- Individuals who are post-solid organ transplantation.
A fourth/booster vaccine dose is recommended and funded for:
- Individuals aged under 26 years who are post-chemotherapy AND who completed three doses of Gardasil® vaccine prior to commencing chemotherapy.
The vaccine is recommended but not funded for:
- Females who are not eligible* for funded vaccine and within the age group of 9 through 45 years.
- Males aged 9 through 26 years.
- HIV positive individuals aged 26 years or older.
* Non-resident girls aged under 18 years can only receive funded Gardasil vaccine if they are staying in New Zealand for longer than nine months.
* Non-resident girls aged 18 years or older are not eligible to receive funded Gardasil vaccine.
There is no treatment for HPV infection. Most HPV infections will clear without intervention.
Most genital warts clear up spontaneously over time. However, many people prefer to have them treated because they can be uncomfortable and/or unpleasant to look at. Treatments for genital warts include the application of chemicals, e.g., solutions and creams, cryotherapy (freezing the wart off), laser therapy and surgery. With the exception of surgery treatment of warts takes several applications/visits and may need a variety of approaches.
Treatment for cervical cancer means removing abnormal cells. In the early stages cauterisation (burning), laser surgery, cone biopsy or loop excision may be effective. In more severe cases hysterectomy, the surgical removal of the uterus and cervix or removal of the uterus and about two centimetres of upper vagina and tissues around the cervix may be required. The ovaries, fallopian tubes and lymph nodes in the pelvis may also need to be removed. Radiation treatment may be used when a woman is not well enough for major surgery or if the cancer has spread into the tissues surrounding the cervix. Chemotherapy may also be used alone or in combination with radiation treatment.