It has been known for over 40 years that certain viruses can cause cancer. The first such “oncovirus” to be identified was Epstein-Barr virus (EBV), which was associated with lymphoma in 1964. Since then, several other human cancer viruses have been discovered; together, they account for an estimated 12% of malignancies worldwide.
There are two ways in which infection with a virus can lead to cancer, termed “direct oncogenesis” and “indirect oncogenesis.”
Not everyone infected with an oncovirus will develop cancer. In fact, in most people an oncoviral infection causes no symptoms at all, a mild illness only, or a non-cancerous condition (e.g hepatitis in the case of the hepatitis viruses).
Seven viruses are currently known to cause cancer in humans.
The recent discovery of MCV, suggests that other, currently unknown oncoviruses are likely to be identified in future studies.
The number of cases of cancer each year, particularly in developing countries, would be greatly reduced if these viral causes could be eliminated. Two vaccines against oncoviruses are currently available – HBV vaccine (given routinely to infants in many countries) and HPV vaccine (recommended for girls or young women, though also available for males). Creating vaccines against the other oncoviruses is the subject of major research worldwide.
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Herpes is caused by the virus herpes simplex and an estimated one in six people suffer from this disease worldwide. There are two common types of this virus: herpes simplex 1, which is milder and usually occurs around the mouth and lips and herpes simplex 2, which is more severe and usually occurs around the genitals.
Gonorrhea is a sexually transmitted infection (STI) caused by the bacterium Neisseria gonorrhoeae. This infection comes about through sexual contact with an infected person. This includes oral, anal and vaginal sex. A good number of victims may not show any signs or symptoms of the disease. In men, the condition manifests itself as a burning sensation with urination, discharge from the penis, or testicular pain. Females also reported a burning sensation when urinating, vaginal discharge, vaginal bleeding between periods, or pelvic pain.