By: Thandiwe Kubere
Taking care of one’s health is a matter that can never be stressed in life. Good health does not only potentially extend one’s life, but it also helps in enjoying it. It has been said, people in good health are generally happier and have a more positive outlook on life. Therefore, the World Health Organization (WHO) advised individual to pay attention and beware of the Human Papillomavirus (HPV), as well as the life risks it comes with.
Human papillomavirus (HPV) is a small, non-enveloped deoxyribonucleic acid (DNA) virus that infects skin or mucosal cells. The circular, double-stranded viral genome is approximately 8-kb in length. The genome encodes for 6 early proteins responsible for virus replication and 2 late proteins, L1 and L2, which are the viral structural proteins. At least 13 of more than 100 known HPV genotypes can cause cancer of the cervix and are associated with other anogenital cancers and cancers of the head and neck.
The two most common genotypes (HPV 16 and 18) cause approximately 70% of all cervical cancers. HPV was estimated to cause almost half a million cases and 250,000 deaths from cervical cancer in 2002, of which about 80% occurred in developing countries. The two genotypes cause genital warts, a common benign condition of the external genitalia that causes significant morbidity. HPV is highly transmissible, with peak incidence soon after the onset of sexual activity, and most persons acquire infection at some time in their lives.
Pathologist Danny Milner, revealed that an individual can become infected with more than one type of HPV, and the disease is only known to affect humans. More than 40 types may be spread through sexual contact and infect the anus and genitals. Moreover, Risk factors for persistent infection by sexually transmitted types include early age of first sexual intercourse, multiple sexual partners, smoking, and poor immune function. These types are typically spread by sustained direct skin-to-skin contact, with vaginal and anal sex being the most common methods. HPV infection can also spread from a mother to baby during pregnancy, HPV is not killed by common hand sanitizers and disinfectants, increasing the possibility of the virus being transferred via non-living infectious agents called fomites.
According to Mayo Clinic, in most cases, the body’s immune system defeats an HPV infection before it creates warts. When warts do appear, they vary in appearance depending on which kind of HPV is involved:
There are genital warts. These appear as flat lesions, small cauliflower-like bumps or tiny stem-like protrusions. In women, genital warts appear mostly on the vulva but can also occur near the anus, on the cervix or in the vagina. In men, genital warts appear on the penis and scrotum or around the anus. Genital warts rarely cause discomfort or pain, though they may itch or feel tender.
Common warts. Common warts appear as rough, raised bumps and usually occur on the hands and fingers. In most cases, common warts are simply unsightly, but they can also be painful or susceptible to injury or bleeding.
Plantar warts. Plantar warts are hard, grainy growths that usually appear on the heels or balls of your feet. These warts might cause discomfort.
Flat warts. Flat warts are flat-topped, slightly raised lesions. They can appear anywhere, but children usually get them on the face and men tend to get them in the beard area. Women tend to get them on the legs.
Studies have revealed nearly every sexually active individual is infected by HPV at some point in their lives. This is because HPV is the most common sexually transmitted infection (STI), globally. Moreover, high-risk HPVs cause about 5% of all cancers worldwide, with an estimated 570,000 women and 60,000 men getting an HPV-related cancer each year. Cervical cancer is among the most common cancers worldwide, causing an estimated 604,000 new cases and 342,000 deaths in 2020. About 90% of these new cases and deaths of cervical cancer occurred in low- and middle-income countries. Roughly 1% of sexually active adults have genital warts. Cases of skin warts have been described since the time of ancient Greece, but that they were caused by a virus was not determined until 1907.
HPV vaccines can prevent the most common types of infection. To be most effective, inoculation should occur before the onset of sexual activity, and are therefore recommended between the ages of 9–13 years. Cervical cancer screening, such as the Papanicolaou test (“pap smear”), or examination of the cervix after applying acetic acid, can detect both early cancer and abnormal cells that may develop into cancer. Screening allows for early treatment which results in better outcomes and has reduced both the number of cases from cervical cancer.
Two prophylactic HPV vaccines have been available since 2006. Both vaccines are prepared from virus- like particles (VLPs) produced by recombinant technology. Purified L1 protein self-assembles to form empty shells that resemble HPV VLPs. These vaccines do not contain viral genetic material or live biological product, so they cannot multiply and are not infectious. These two vaccines are:
A bivalent vaccine comprised of HPV types 16 and 18 protein expressed and purified from insect cells infected with a recombinant baculovirus. This vaccine is formulated with a novel adjuvant, AS04, which contains aluminium hydroxide and monophosphoryl lipid A (MPL); and A tetravalent vaccine comprised of HPV types 6, 11, 16 and 18 expressed and purified from yeast cells containing the specific L1 expression plasmids.
The VLPs are adsorbed to an amorphous aluminium hydroxyphosphate sulfate adjuvant. Both vaccines induced high levels of serum antibodies against all vaccine-related types in more than 99% of females aged 9–45 years (quadrivalent vaccine) or 10–55 years (bivalent vaccine). Neutralizing antibodies to HPV are thought to be important in protection. However, so far, a serologic correlate of protection has not been identified, and the minimum antibody level required for clinical protection is unknown.
In 2006 WHO held a series of consultations to develop guidelines for prophylactic human papillomavirus (HPV) vaccines. The document provides background and guidance to national regulatory authorities and vaccine manufacturers on the production, quality control and evaluation of the safety and efficacy of recombinant HPV virus-like particle (VLP) vaccines.
Therefore, having been warned about the dangers which come with HPV, people are urged to be cautious and make sure to avoid the risk factors so as to lead healthy lives.