HPV - Human Papilloma Virus
HPV stands for the human papillomavirus. HPV denotes a group of related virus (more than 150) and each one of them is a given a number to identify them uniquely. This unique identification is referred to as the type of HPV virus (for example HPV type 16 and so on).
Papilloma stands for small wart-like growths on the skin and mucous membrane which originates from the epidermis and is usually benign in nature. That is why HPV is named so since some of the important HPV types commonly cause warts in humans. We know of at least 13 HPV types that may also cause cancer in both males and females. Of the 13 HPV types, HPV 16 and 18 are the most dangerous and are known for their cancer-causing nature. Thus increasing one's knowledge regarding the HPV and equipping oneself with adequate protective measures (such as getting vaccinated) is the best thing one can do when combating the HPV. In fact, HPV cancer is one of the only two cancers that may be prevented by vaccination!
HPV Cancers common to both men and women are:
- Mouth cancer
- Throat cancer
- Rectal cancer
- Anal cancer
HPV Cancers that occur in women:
- Cervical cancer
- Vaginal cancer
- Vulvar cancer
HPV Cancers that occur in men:
- Penile cancer
Structure of the HPV
HPV is a small non-enveloped DNA virus. DNA stands for deoxyribonucleic acid and contains the genetic information of the virus. The HPV DNA is double-stranded, circular in shape and has a length of about 80-kb. "kb" stands for kilobase(pairs) which is a unit of measurement in molecular biology. 1 kb stands for 1000 bp (base pairs) whereas 1 bp is equivalent to 3.4 Å (Ångström) or 340 pm (Picometre). Thus 80 kb means around 27200000 pm or 27200 nm (Nanometre) or 0.0272 mm (Millimeter).
The HPV DNA contains information which the HPV use to create different proteins:
- 6 early proteins responsible for HPV replication
- 2 late proteins (L1 and L2) responsible for HPV structure
The circular HPV DNA is surrounded by a protective layer called the capsid. Capsid is basically the protein shell of a virus. Capsid protects the blueprint of the HPV - the DNA - and transfers it from one host to the next.
Even though the HPV is non-enveloped, which means it does not have an extra layer of protective membrane (usually made of lipid) covering the capsid, it can survive in harsh environment and are extremely virulent (Virulency denotes the ability of a microorganism such as a virus to cause a disease). Since the virus does not have any envelop, capsid contains all the protein and enzymes necessary for the HPV to copy itself and survive.
HPV transmission: How does one get infected with HIV?
HPV is the most common sexually transmitted infection (STI) in the world. Chances of acquiring HPV is increased by the following factors:
- Early age of first intercourse
- Multiple sexual partners
Sexual Transmission of HPV
Any form of sex (vaginal, anal, oral) with an infected individual can lead to HPV infection.
Vertical Transmission of HPV
HPV may also be transmitted from a mother to her child during childbirth (vertical transmission)
HPV Transmission by sharing objects
HPV may also be transmitted by using infected objects like razors.
Blood Transfusion may transmit HPV
It has been suggested that blood transfusion may be a possible route of transmission of the HPV. Some studies found HPV DNA in blood samples donated by healthy donors. However, detecting the HPV DNA in blood is not the same as detecting the HPV itself in blood and as such no conclusive conclusion regarding whether HPV can be transmitted via blood transfusion has been reached. This is particularly important since HPV infected individuals are not prevented from donating blood and the blood samples are not routinely screened for HPV.
Hospital Transmission of HPV
Surgeons or anyone in the operating room are at high risk of acquiring the HPV. This can occur during removal of HPV warts by either electrocautery or laser surgery which releases a large number of the HPV in the air which is then inhaled by the OT stuff. In fact, it has been reported that a laser surgeon was infected with serious HPV infection in the throat after he operated on a patient with HPV warts.
HPV Infection: Symptoms and Signs (Clinical Features)
Before discussing the sign and symptoms of HPV infection, it is crucial that we define what the term "infection" actually means.
What is the definition of "INFECTION"?
Infection may be defined as the invasion and subsequent multiplication of a microbe (bacteria/virus/parasite) in or on a host which may or may not result in the development of symptoms.
This definition of the term infection makes sense when we realize that most people infected with HPV do not have any symptoms or health problems. It is particularly important to understand and pay attention to this concept because subclinical infections (infections with no symptoms) result in the development of High-risk HPV infection which ultimately may give rise to serious complications such as HPV cancer. That is why it important to go for regular check-ups, even if one shows no sign of infection.
Symptoms of HPV vary by the HPV type. As mentioned before, some HPV infection do not manifest in any symptoms. This is particularly true for HPV 5, which may cause infection for a lifetime but not result in the development of clinical symptoms. On the other hand, some other HPV infection may manifest as anogenital warts or laryngeal papillomatosis. Some High-risk HPV infection may even unfortunately present as HPV cancer.
2, 7, 22
1, 2, 4, 63
3, 10, 28
6, 11, 42, 44 and others
6, 16, 18, 31, 53, 58
Anal dysplasia (lesions)
Highest risk: 16, 18, 31, 45
Other high-risk: 33, 35, 39, 51, 52, 56, 58, 59
Probably high-risk: 26, 53, 66, 68, 73, 82
more than 15 types
Focal epithelial hyperplasia (mouth)
6, 7, 11, 16, 32
That's all for today!
In the next article, we will discuss more in-depth about the HPV treatment, HPV vaccine, High-risk HPV and other aspects of the HPV.