Human papillomavirus (HPV) is a virus which affects humans. Some of its effects are classed as sexually transmitted disease (STD).

Scientists have identified more than 100 types of HPV, most of which are harmless. About 30 types are spread through sexual contact. Some types of HPV that cause genital infections can also cause cervical cancer and other genital cancers.

Like many STDs, genital HPV infections often do not have visible signs and symptoms. One study in the USA sponsored by the National Institute of Allergy and Infectious Diseases (NIAID) reported that almost half of the women infected with HPV had no obvious symptoms. People who are infected but who have no symptoms may not know they can transmit HPV to others or that they can develop complications from the virus.

Prevention

The only way to prevent getting an HPV infection is to avoid direct contact with the virus, which is transmitted by skin-to-skin contact. If one's sexual partner has warts that are visible in the genital area, one should avoid any sexual contact until the warts are treated. Studies have not confirmed that male latex condoms prevent transmission of HPV itself, but results do suggest that condom use may reduce the risk of developing diseases linked to HPV, such as genital warts and cervical cancer.

Effects

Genital warts

Genital warts (condylomata acuminata or venereal warts) are the most easily recognized sign of genital HPV infection. Many people, however, have a genital HPV infection without genital warts.

Common skin warts

Some types of HPV (e.g. HPV 1) cause common skin warts, such as those found on the hands and soles of the feet (plantar wart). These types of HPV do not cause genital warts.

Cancer

Some types of HPV (HPV 16,18,31) can cause cervical cancer, anal cancer, and cancer of the penis (a rare cancer). These viruses have also been associated with cancers of the head and neck. These tumours often have HPV viral sequences integrated into the cellular DNA. Some of the genes encoded by these viruses are known to act as oncogenes. The viral E6 protein binds to and degrades the cellular protein p53 while the viral E7 protein interferes with the retinoblastoma protein.

HPV 30, 40 cause laryngeal carcinoma.

Most HPV infections do not progress to cervical cancer. If a woman does have abnormal cervical cells, a Pap smear will detect them. It is particularly important for women who have abnormal cervical cells to undergo colposcopy so that precancerous and cancerous lesions can be detected and treated early, if necessary.

Research

Scientists are doing research on two types of HPV vaccines. One type would be used to prevent infection or disease (warts or pre-cancerous tissue changes). The other type would be used to treat cervical cancers.[1] (http://news.bbc.co.uk/2/hi/health/3964263.stm) Researchers are testing both types of vaccines in people.

USA

Human papillomavirus is one of the most common causes of sexually transmitted disease in the United States. For example, health experts estimate that there are more cases of genital HPV infection than of any other STD in the United States. According to the American Social Health Association, approximately 5.5 million new cases of sexually transmitted HPV infections are reported every year. At least 20 million Americans are already infected.

External links

• American Social Health Association (http://www.ashastd.org)
• National Cancer Institute (http://cancernet.nci.nih.gov)