VACCINATION AGAINST HUMAN PAPILLOMAVIRUS
Life Science Research Project
August 2020
By Isabella Rowley
Grade 11
,PART 1
Overview of HPV
Human Papillomavirus (HPV), is the name of a large group of viruses, most commonly
classified by infections in the genital area (mucosal HPV) or on the skin (cutaneous HPV).
Mucosal HPV one of the most common sexually transmitted diseases as it is spread by
sexual skin to skin contact. There are over 100 types of mucosal HPV infections, with most
people contracting HPV at least once in their lives. Over 90% of HPV infections present as
asymptomatic or disappear naturally within 2 years without posing a major health risk,
while a few strains (Types 6 and 11) can cause non-cancerous genital warts to appear.
These strains are collectively known as Low Risk HPV. However, there are about 12
strains of High Risk HPV that can lead to possible cancers, with two strains, Type 16 and
Type 18, that cause cervical cancer. Contracting a High Risk strain does not progress to
cancer in most people, as the body’s immune system typically rids it of the infection.
(Types of Human Papillomavirus, 2020)
In many Low Risk HPV infections there are no symptoms, although cauliflower shaped
warts can appear on or around the genitals in both women and men, causing discomfort
and irritation. Unfortunately, when infected with a High Risk HPV strain symptoms do not
present until it has caused serious health issues. Only when a strain of this kind has
progressed to cancer will symptoms be obvious. (Planned Parenthood, 2020). HPV can be
transmitted when the infected person has no symptoms of the infection, commonly through
vaginal, oral and anal sex.
How HPV leads to cervical cancer
High Risk strains of HPV can lead to many different types of cancer, such as cancer of the
vagina, penis, anus or back of the throat. These cancers usually only develop years after
contracting HPV, if not eliminated by the body’s immune system, making people with
weaker immune systems (such as those living with HIV/AIDS) more susceptible to health
problems. The cancer most commonly linked to HPV is cancer of the cervix. Factors
causing people to be more likely to develop cervical cancer from HPV also include
smoking, being overweight and the use of oral contraceptives. (Burnett, 2019)
Types 16 and 18 of HPV cause account for 70% of all cervical disease, including the more
common outcome of cervical dysplasia, referring to the cell changes in the cervix at the
opening of the uterus. (Trimble, 2020). These two strains are also responsible for 90% of
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, all cervical cancer cases, as if the cervical dysplasia is not monitored or treated it can
advance to cervical cancer, the second most common cancer in women in South Africa.
(Denny and Kuhn, 2017)
Cervical cancer occurs when the cells in the lining of the cervix begin to multiply at an
uncontrollable rate to form a malignant tumor. It begins as HPV enters the body through an
abrasion in the skin, and wounds in the epithelial tissue of the cervix. (Osmosis, 2019) It
begins to infect the basal cells of epithelium of the cervical mucosa, on the surface of the
cervix. These basal cells are responsible for cell differentiation which is the process of
changing a cell into a more specialized cell. HPV integrates it’s viral DNA
(Deoxyribonucleic Acid) with that of the host cell, also inserting oncogenes into the host
cell thus mutating into an abnormal cancer cell. The virus promotes proliferation, the rapid
increase and growth of the virus, in differentiating basal cells. (White, 2019) These
abnormal, basal cells now known as carcinomas, replicate uncontrollably forming more
cells with a damaged DNA structure and oncoproteins , resulting in a potentially malignant
tumor forming. As the cells continue to multiply, the tumor spreads into the deeper tissues
by breaking through the basement membrane of the epithelium of the cervix to invade
other areas of the body. (Burd, 2003)
Types of HPV Vaccines Available in South Africa
In South Africa two HPV vaccines are available to the public, Cervarix and Gardasil. They
both protect against many strains of HPV, but especially focusing on cancer causing
strains in both men and women. Gardasil is used to protect against a wide range of
strains, especially Type 16 and 18 of HPV, in women to reduce the risk of cervical cancer
and, in men to prevent anal cancer. Additionally, Gardasil does protect against the strains
causing genital warts. Cervarix is used only to prevent cervical cancer in women aged 9 to
25, and specifically preventing diseases caused by Type 16 and 18 of HPV which are
linked to cervical cancer. Both are given in 2 doses, usually when aged 11 or 12 years old,
or 3 doses when aged 15 to 26 years old. It should ideally be given before becoming
sexually active. In adults aged 27 to 45, the vaccines proved to be less effective as HPV
had usually been contracted prior to vaccination. Cervarix was reviewed and found to be
more cost effective that Gardasil, and therefore likely to be the first choice for patients.
There is no current evidence of long term side effects of either vaccine, and are
considered to be safe and efficient. (Scaccia, 2019)
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