Types of HPV Strains and Symptoms

Different HPV Strains Cause Different Symptoms

Doctor talking to a patient about the strains and symptoms of HPV infections
What are the different strains of HPV and what symptoms do they cause. Hero Images/Getty Images

The human papillomavirus (HPV) has been a popular topic in the media since the FDA approval of Gardasil, the first of three HPV vaccines. You've likely heard that HPV is extremely common and may have worried about whether you could be infected. At the same time, you may feel anxious hearing that the virus can cause both cervical cancer and genital warts.

Are there symptoms or signs you should watch for? Much of the confusion lies in understanding the different strains of HPV. Let's clear up some of the confusion and review what we know about this virus so you can be an empowered advocate for your own health care.

The Different Strains of Human Papillomavirus (HPV)

There are thought to be over 100 different strains of the HPV virus. Roughly 30 of these viruses are known to affect the male and female genitalia but do so in different ways. Not all strains are linked to cervical cancer. The strains of HPV which infect humans have been broken down into two categories based on whether they are considered high risk or low risk.

  • Low-Risk Strains: Strains classified as "low risk" are associated with genital warts and mild cervical abnormalities that are sometimes found on Pap smears. Low-risk strains do not cause cervical cancer and are considered "non-oncogenic strains." HPV 6 and HPV 11 are low-risk strains and are responsible for around 90 percent of genital warts. The strains which cause genital warts and those which cause cervical cancer are different. In other words, if you have had genital warts you do not need to worry that the same virus will cause cervical cancer.
  • High-Risk Strains: Strains of HPV classified as "high risk" are associated with both mild and severe cervical abnormalities found on a Pap smear and are the strains which can lead to cervical cancer. In other words, these are the "oncogenic strains" of HPV. Strains that have been associated with cancer include HPV 16 and 18 (which cause 70 percent of cervical cancers) as well as HPV 31, 33, 35, 45, 52, 58, and 59. Most of the time, the virus is present for a lengthy period of time and cervical changes progress from mild dysplasia to cervical dysplasia and eventually cancer. That said, cervical cancer has sometimes occurred within shorter periods of time after acquiring the virus. Less commonly, high-risk strains may cause atypical genital warts that can have precancerous and cancerous changes within them. It's important to note that HPV can lead not only to cervical cancer but has been implicated in penile cancer, anal cancerhead and neck cancer (responsible for one in two cases), and, perhaps other cancers such as lung cancer.

    Engaging in high-risk sexual behavior increases your risk of contracting both high and low-risk strains of HPV.

    It's important to note that you can be infected with more than one strain of HPV, and the risk factors which predispose a person to acquire one strain (or developing any sexually transmitted disease) can lead to infection with other strains.

    The good news is that for most people, both high and low-risk HPV infections clear up without medical intervention. We don't know why HPV persists in some people instead of others. We do know that risk factors such as a suppressed immune system and smoking can make this more likely.

    HPV Symptoms

    In looking at the symptoms of HPV it's important to break these down into the symptoms related to genital wart-causing strains and the symptoms of cervical cancer-causing strains. Most of the time a person will not have any symptoms if infected with these viruses.

    Symptoms of HPV-related genital warts: The strains of HPV known to cause genital warts in men and women cancer may or may not result in the formation of warts. When they do, the cauliflower-like growths (both very large and very small) can appear in and around the genitals and surrounding areas.

    The appearance of warts can occur immediately, or instead many years after you contract the virus, so the appearance of warts is not a good way to determine whether you are infected or not.

    Symptoms of HPV-related cervical cancer: Early on, the cancer-causing strains of HPV do not generally produce symptoms. For this reason, following the guidelines for regular Pap smears is critical. Pap smears can very often (but not always) detect abnormal cervical changes caused by HPV long before they turn cancerous. The most common symptoms of cervical cancer include abnormal bleeding (bleeding between periods, after intercourse, or after menopause), pelvic pain, and vaginal discharge.

    Since there are many conditions which can cause these symptoms—many of which are more common than cervical cancer—there isn't a simple way to watch for the signs. Regular Pap smears and talking to your doctor about any symptoms which concern you is key to detecting changes early.

    Diagnosing HPV in Women

    For women, a regular pelvic exam and Pap smear is the best way to detect an HPV infection. During a pelvic exam, your doctor may examine your vagina for signs of genital warts. If genital warts are discovered, she will discuss the treatment options available. If you do have genital warts, please keep in mind that the HPV strain that causes warts (with the exception of atypical warts) is not a strain that can lead to cervical cancer. A regular Pap smear very often detects a high-risk HPV infection that could lead to cervical cancer.

    Depending on your age, a routine HPV test may be done as well. Current guidelines state that women over the age of 30 should be offered a routine HPV test along with their Pap smear. Not all doctors do this routinely, however, and you may need to ask to have the test done. For women under the age of 30, an HPV test may be recommended if your Pap smear is abnormal. As with women over the age of 30, it's important to be your own advocate and request testing if you feel it is needed. Doctors vary widely in their approaches to this issue.

    Diagnosing HPV in Men

    Unfortunately for men, there is no medical screening test that can determine if you are infected with HPV. A doctor can visually examine the genitals for the presence of male genital warts, but again, warts are not caused by the same strains that cause cancers such as cervical cancer, penile cancer, and more. It is rare for men to have any symptoms at all when infected with the cancer-causing strains of HPV. This is one reason, for those who are dating, to be careful even if a potential partner has had negative tests for sexually transmitted diseases. We simply do not have any good way to test for the presence of HPV in men at the present time.

    HPV Vaccines and the Strains They Cover

    In 2018 there are now three different HPV vaccines available. These differ in the specific strains of HPV they cover. Some people have preferences of one vaccine over another, but health insurance companies usually provide coverage for only one or two of these. Current vaccines include:

    • Gardasil. Gardasil was approved in 2006 as the first HPV vaccine. It is effective against HPV 6, 11, 16, and 18. Since the combination of HPV 16 and 18 are responsible for 70 percent of cervical cancers, the vaccine should, in theory, protect against 70 percent of cervical cancers. HPV 6 and HPV 11 cause 90 percent of genital warts, so the vaccine should theoretically prevent 90 percent of such warts.
    • Cervarix: Cervarix was approved in 2009 and protects against HPV 16 and HPV 18. As with Gardisil, since HPV 16 and 18 are thought to cause 70 percent of cervical cancers, the vaccine should theoretically prevent 70 percent of these cancers. The strains of HPV responsible for most genital warts are not present in this vaccine, so it likely offers little protection against genital warts.
    • Gardasil 9: Approved in 2014, Gardisil 9 offers further coverage, and is considered effective against HPV 6, 11, 16, 31, 33, 45, 52, and 58. Like the other vaccines, Gardasil 9 should prevent at least 70 percent of cervical cancers but likely protects against more due to offering protection against oncogenic strains 31, 33, 45, 52, and 58. It should also protect against most genital wart causing strains.

    Treatment of HPV

    The treatment of HPV will depend on the symptoms and strains of the virus. There are a number of treatment options for genital warts. As far as treatment of the cancer-causing strains of HPV, the specific treatments will depend on the  abnormalities found on a Pap smear.

    When only mildly abnormal and thought to be due to HPV, a Pap smear may simply be repeated. If there is some concern, a colposcopy is recommended. During a colposcopy, a cervical biopsy may be done to look at the cells of concern. Other procedures, such as a cone biopsy may be considered if further abnormalities are found. If cancerous cells are found, treatment options range from local treatment options to doing a hysterectomy.

    Though anti-viral medications are available for some viral conditions such as the flu, chickenpox, and HIV, we do not currently have an anti-viral medication which is routinely used to treat HPV. For this reason, the goal of treatment is to monitor people for the complications of the virus such as cervical abnormalities, cervical cancer, and genital warts, and treat them if they should occur.

    Bottom Line on the Strains and Symptoms of HPV

    There are many different strains of HPV and this is a source of great confusion. The media tells people that almost everyone has been infected, but not all, or even most, infections result in clinical symptoms. Some strains can lead to genital warts, for which there are many treatments available. Of greater concern is that some strains can lead to cervical cancer. Getting regular Pap smears is the key to prevention as HPV infections which lead to cancer rarely cause symptoms that can lead to early detection. Instead, Pap smears and HPV testing can direct people to further procedures such as a colposcopy to define the problem. At the current time, we don't have any specific treatments designed to rid the body of the HPV virus, though we do have immunizations available which can prevent many of these infections, and hence, the problems they cause.


    Centers for Disease Control and Prevention. Human Papillomavirus (HPV). Genital HPV Information—Fact Sheet. Updated 11/16/17. https://www.cdc.gov/std/hpv/stdfact-hpv.htm

    McNamara, M., Batur, P., Walsh, J., and K. Johnson. HPV Update: Vaccination, Screening, and Associated Disease. Journal of General Internal Medicine. 2016. 31(11):1360-1366.