More Information about HPV : Part 1
Boris JIVKOV, Obstetrician and Gynecologist
Strictly speaking, viruses are not living creatures. The word “virus” originates from Latin, and means “poison”. They are more like chemical compounds, neither defined by birth and death, nor able to consume, produce or store energy, nor to reproduce themselves. They have been around much before humankind appeared, and have been inherent part of our evolution, mostly being a quiet parasite, sometimes inflicting bothersome, but temporary discomfort, like the common cold, but also causing life threatening conditions and death.
One of them, the human papilloma virus (HPV), causes infections in the outer layer of human skin, visible and palpable, the common warts. It is actually a group of more than 150 closely related viruses, that all have preferences for certain body parts and types of skin: the hands, or feet, the mouth or ano-genital mucosa (the pink, moist skin that covers the insides of the mouth, vagina, anus, or the penis). Because of the specific preferences to skin type, it is unlikely, for example, for finger warts to cause genital warts.
About 40 subtypes of the HPV have a preference to the mucosa of the human genitalia and the anus, and are so common, that it is considered that 80% of all people have been infected at some point in their lives. Before becoming sexually active, it is extremely unlikely to find them on our mucosa! Yet, even women who had not experienced penetrative intercourse with a male partner, but have same-gender partners, are at risk. Inherently, our immunological defense systems build antibodies and while we can disseminate the virus even without having genital warts, we also are very likely to get rid of it over time.
Out of this smaller group, 13 HPV sub-types are linked to ano-genital cancer. While cancer of the anus and the penis are rare, these have caused in 2018 alone 570 000 cases of cervical cancer and 311 000 deaths worldwide. In a group of women, infected by the virus, the immune response does not work well, either being compromised by environmental factors like tobacco use, or weakened by the virus of AIDS . At the tip of the uterine cervix exists a particular weakness point, the transition of the mucosa, covering the inside of the uterus to the mucosa, covering the vagina. In this so called Transformation Zone (TZ) HPV thrives and may persist for many years, bringing on gradual changes of the normal human cells. This process is slow, over 10 or more years, and while initially the changes are not cancerous, they are very specific. Way before we knew about the role of the virus, in the nineteen twenties, a Greek physician, George Papanicolaou , working at Cornel University in the USA, realized that by taking a superficial gentle scrape from the cervix, smearing it onto a glass slide and analyzing it under the microscope, one can detect these changes before they turn into cancer.
To date, the Pap smear, named after its inventor, has been one of the first and most effective screening tests in medicine, instrumental in reducing the number of cervical cancer worldwide. It had been calculated, that by having a gynecological visit once a year after becoming sexually active, the Pap smear would detect 95-97% of early pre-cancer changes and prompt adequate treatment.
On the other hand, by understanding the role of HPV, the ability to detect its’ presence in the body and the development of the HPV vaccine, the early detection and prevention of cervical cancer has changed dramatically. We will discuss this in our next month’s article.