Human papillomaviruses (HPV): How can you be infected and what consequences can that have?

The viruses are nearly always spread through direct contact of skin and mucous membranes in the genital area. Because any part of the genital area can be infected, any intimate skin contact – not only sexual intercourse – could lead to infection. Viruses might also be spread during oral sex if mucous membranes in the mouth touch areas of skin infected with HPV. The viruses are not spread though semen, blood or saliva.

HPV infections are very common. That is why many sexually active men and women who are not vaccinated become infected at least once in their lives. The body’s immune system usually fights off the viruses successfully, and they disappear without having caused any symptoms or other problems. People can get infected with HPV more than once.

The rate of infection is similar in women and men, and they can then pass on the infection. The possible consequences of the infection, such as cancer, are less common in men, though. The risk of infection in women is highest up until the age of about 30.

The viruses are occasionally passed on to the newborn during birth. These infections are usually harmless, though, and they go away on their own after a while. In rare cases they can cause non-cancerous (benign) tumors in the larynx, called laryngeal papillomatosis. These tumors can cause hoarseness and breathing problems in children.

Human papillomaviruses, which may cause cancer, can be detected in an HPV test. This test is offered to women aged 35 and over as part of cervical cancer screening. It involves taking a "smear" sample of the cells from the lining of the cervix to see whether they have been infected by the virus. The HPV test is combined with a Pap test, which can detect changes in the tissue lining the cervix.

HPV infections usually go unnoticed, do not cause any symptoms and clear up on their own. More than 200 different types of HPV are currently known. Some cause warts on the skin (also called papillomas), which may appear on your face, hands or feet. About 40 different types of HPV can infect skin and mucous membranes in the genital area and are spread through sexual contact. People can have several different types of HPV at the same time.

Some kinds of HPV can cause unpleasant but harmless genital warts (also called condylomas). On average, about 1% of the population have these kinds of genital warts, but they are more common in sexually active young people. In about a third of the people who have them, these warts go away on their own. The most common harmless virus types are HPV 6 and HPV 11.

Certain HPV types often enter the cells of the mucous membrane around the opening of the cervix, where the vagina and cervix meet. This can lead to abnormal changes in the tissue (dysplasias). Over time, these changes can develop into cervical cancer. But that rarely happens. Twelve virus types are known to increase the risk of cervical cancer. The main ones are HPV 16 and 18. These are also the types of HPV that are most often found in tumor tissue.

HPV infections can also increase the risk of vulvar cancer, penile cancer and anal cancer, as well as cancers affecting the mouth and throat. These types of cancer are less common than cervical cancer, though.

Because HPV is so common, you can already become infected with HPV the first time you have sexual contact with someone. To be sure that you do not become infected, you would have to not have sex at all or only with people who definitely don't have an HPV infection and are not sexually active with anyone else.

Condoms lower the risk of infection, but don’t offer 100% protection from HPV because they don’t cover all of the possibly infected areas of skin in the genital area. Condoms and femidoms (condoms for women) can also help prevent many other sexually transmitted infections.

Girls and boys can be vaccinated to prevent infection with certain types of HPV. This also reduces the risk of cervical cancer and other types of cancer. The vaccine is recommended for children between the ages of 9 and 14 years. It is also possible to get the vaccination as an adult, but it is less effective then.

Because women are examined more frequently than men, they are also more likely to have an HPV infection detected – most likely during cervical cancer screening. It is then not possible to tell which of the partners in a relationship was infected first or how long they have had the infection. But that also has no consequences for the development of the infection, which is usually harmless. Either partner can infect the other again.

Some human papillomaviruses can cause genital warts. Many genital warts can’t be seen or felt, but some form hard nodules with an uneven surface. These warts typically develop around the opening of the vagina in women, or between the head and the shaft of the penis and at the base of the penis in men. Their size ranges from just a few millimeters to several centimeters, and they may be a reddish, brownish, or whitish color. They usually appear in clusters. Depending on their size and location, they can cause symptoms like itching or burning.

In about a third of the people who have them, these warts go away on their own. Genital warts can be treated with a cream or a solution, or they can be removed surgically. The treatment options will depend on the texture and location of the warts, and how far they have spread.