Human papilloma virus (HPV) is commonly transmitted between humans through their skin or moist membrane linings such as in the vagina, anus, mouth, or throat. Low risk HPV can result in no easily identifiable symptoms but high risk HPV can even lead to cancer. There are over 100 types of HPV viruses and each one is given a virus number to differentiate them.
Each of the different types, however, exhibits the key characteristics of viruses. Each infectious virus microbe will have a nucleic acid either in the form of deoxyribonucleic acid (DNA) or ribonucleic acid (RNA), surrounded by a capsid made out of protein. Being viruses, they can only survive by thriving in living cells that become hosts. They transfer genetic information to these cells and governing how they behave.
Low risk HPV viruses can cause warts around the skin areas where the virus has come into contact such as the genitals, anus, mouth, and throat. In very rare cases, it can also cause tumors in the nose, mouth and lungs. About a dozen high risk HPVs can lead to cancer.
There are more than 40 types of the virus that cause infections in the genital area. People do not always realise they have been infected with the virus as it does not always cause symptoms. Visible ways by which it is expressed are as genital warts which develop after sexual contact. When it is transmitted through skin to skin interaction in genital areas of the body, the virus is highly infectious.
A person only needs to have sexual contact with one person infected with the virus to become infected, although reducing the number of sexual partners can reduce the risk of this happening.
- In the US, this virus is the most common sexually transmitted infection. Every year about 14 million people are newly infected
- In the UK, it is the second most common sexually transmitted infection.
- About 79 million Americans are infected with HPV
Effect of HPV on the body
HPV can result in changes in the cells and lead to abnormal tissue growth. Some forms of the virus can lead to cervical cancer in women after genital infection. The types of HPV that cause warts usually have a quick transition through the body whereas the types that cause cancer can stay in the body for lengthy periods. These will create pre-cancerous and cancerous lesions in the affected area.
Cervical cancer is the fourth most common cancer affecting women across the world. In 2012 alone, there were about 266,000 deaths and 528,000 new cases of cervical cancer.
Some countries routinely screen women for signs of the disease. In the UK, women aged between 25 and 64 years are invited for screening. Cervical cancer affects the less developed countries disproportionately with 85% of the burden of the disease resting with them. Other cancers caused by HPV include cancers of the vulva, vagina, penis, anus, head, and neck.
Vaccines to protect against HPV infection have been developed. Some countries vaccinate girls to protect them against the most serious forms of the virus. The UK vaccinates them between 12 and 13 years of age.
Reviewed by Susha Cheriyedath, MSc