6. Human papillomaviruses (HPVs) and genital warts
What are HPVs?
More than 40 types of HPV, which are the cause of genital warts (also known as condylomata acuminata or venereal warts), can infect the genital tract of men and women. These warts are primarily transmitted during sexual contact. Other, different HPV types generally cause common warts elsewhere on the body. HPV infection has long been known to be a cause of cervical cancer and other anogenital cancers in women, and it has also been linked with both anal and penile cancer in men.
HPV infection is now considered to be the most common sexually transmitted infection in the US, and it is believed that at a majority of the reproductive-age population has been infected with sexually transmitted HPV at some point in life.
HPV infection is common and does not usually lead to the development of warts, cancers, or specific symptoms. In fact, the majority of people infected with HPV have no symptoms or lesions at all. The ultimate test to detect HPV involves identification of the genetic material (DNA) of the virus.
Of note, it has not been definitively established whether the immune system is able to permanently clear the body of an HPV infection. For this reason, it is impossible to predict exactly how common HPV infection is in the general population.
Asymptomatic people (those without HPV-induced warts or lesions) who have HPV infections are still able to spread the infections to others through sexual contact.
Diagnosis of HPV and genital warts
A typical appearance of a genital lesion may prompt the physician to treat without further testing, especially in someone who has had prior outbreaks of genital warts. Genital warts usually appear as small, fleshy, raised bumps, but they can sometimes be extensive and have a cauliflower-like appearance. They may occur on any sexually-exposed area. In many cases genital warts do not cause any symptoms, but they are sometimes associated with itching, burning, or tenderness.
HPV can sometimes be suspected by changes that appear on a Pap smear, although Pap smears were not really designed to detect HPV. In the case of an abnormal Pap smear, the clinician will often do advanced testing on the material to determine if, and which kind, of HPV may be present. HPV can also be detected if a biopsy (for example, from a genital wart or from the uterine cervix) is sent to the laboratory for analysis.
How is HPV treated?
Treatment of external genital warts
There is no cure or treatment that can eradicate HPV infection, so the only treatment is to remove the lesions caused by the virus. Unfortunately, even removal of the warts does not necessarily prevent the spread of the virus, and genital warts frequently recur. None of the available treatments are ideal or clearly superior to others.
A treatment that can be administered by the patient is a 0.5% solution or gel of podofilox (podophyllotoxin). The medication is applied to the warts twice per day for three days followed by 4 days without treatment. Treatment should be continued up to three to four weeks or until the lesions are gone. Podofilox may also be applied every other day for a total of three weeks. Alternatively, a 5% cream of imiquimod (a substance that stimulates the body's production of cytokines, chemicals that direct and strengthen the immune response) is likewise applied by the patient three times a week at bedtime, and then washed off with mild soap and water 6-10 hours later. The applications are repeated for up to 16 weeks or until the lesions are gone. Sinecatechin 15% ointment, a green-tea extract with an active product (catechins), is another topical treatment that can be applied by the patient. This drug should be applied three times daily until complete clearance of warts, for up to 16 weeks.
Only an experienced physician can perform some of the treatments for genital warts. These include, for example, placing a small amount of a 10% to 25% solution of podophyllin resin on the lesions, and then, after a period of hours, washing off the podophyllin. The treatments are repeated weekly until the genital warts are gone. An 80% to 90% solution of trichloroacetic acid (TCA) or bichloracetic acid (BCA) can also be applied weekly by a physician to the lesions. Injection of 5-fluorouracil epinephrine gel into the lesions has also been shown to be effective in treating genital warts.
Alternative methods include cryotherapy (freezing the genital warts with liquid nitrogen) every one to two weeks, surgical removal of the lesions, or laser surgery. Laser surgery and surgical excision both require a local or general anesthetic, depending upon the extent of the lesions.
Treatment of precancerous changes (dysplasia) of the cervix related to HPV infection
Women who have evidence of moderate to severe precancerous changes in the uterine cervix require treatment to ensure that these cells do not become invasive cancer. In this case, treatment usually involves surgical removal or destruction of the involved tissue. Conization is a procedure that removes the precancerous area of the cervix using a knife, a laser, or a procedure known as LEEP (loop electrosurgical excision procedure, which uses an electric current passing through a thin wire that acts as a knife). Cryotherapy (freezing) or laser therapy may be used to destroy tissue areas that contain potentially precancerous changes.
What should a person do if sexually exposed to someone with genital warts?
Both people with HPV infection and their partners need to be counseled about the risk of spreading HPV and the appearance of the lesions. They should understand that the absence of lesions does not exclude the possibility of transmission and that condoms are not completely effective in preventing the spread of the infection. It is important to note that it is not known whether treatment decreases infectivity. Finally, female partners of men with genital warts should be reminded of the importance of regular Pap smears to screen for cervical cancer and precancerous changes in the cervix, since precancerous changes can be treated and reduce a woman's risk of developing cervical cancer. Similarly, men should be informed of the potential risk of anal cancers, although it is not yet been determined how to best screen for or manage early anal cancer.
The HPV vaccine
A vaccine available against four common HPV types associated with the development of genital warts and cervical and anogenital carcinomas. This vaccine (Gardasil) has received FDA approval for use in males and females between 9 and 26 years of age and confers immunity against HPV types 6, 11, 16 and 18. Another vaccine directed at HPV types 16 and 18, known as Cervarix, has been approved for use in females aged 10 to 15.