Human papillomavirus: characteristics and associated diseases

The human papillomavirus (HPV) is a term that encompasses diverse groups of DNA viruses belonging to the family Papillomaviridae. According to various professional sources, there are more than 200 types of HPV, of which about 40 are correlated with infections in the genital area and sexual contact.

We are facing a viral family that can cause from a slight self-healing wart over time to cervical cancer in women. Of course, it is impressive to know that within the same family, different members can generate such diverse problems in human beings. In addition, of the 16 existing genera, only 5 affect our species, the rest being pathogens for other animals.

To make things more interesting, we will say that it is estimated that more than 90% of people sexually active people have HPV at some point in their life, that is, practically every adult she is contagious. Incredible true? Here's everything you need to know about this multifaceted viral family.

• Related article: "The 4 types of pathogens (and their characteristics)"

What is the human papillomavirus? From wart to cancer

Human papillomavirus infections occur worldwide, that is, there is no country, ethnicity, age, or gender immune to this infectious agent. Before launching into the exciting epidemiology of the disease, let's briefly describe the causative agent.

Small but bully

As we have said previously, the term HPV does not correspond to a specific viral species, but to an entire family. Even so, all the pathogens included in this grouping share a series of characteristics. For example, all of them are DNA viruses (that is, their genome is made up of DNA) with double strands of about 8,000 base pairs. The genome of these pathogens can be divided into an early region (E), a late region (L), and a control region..

As far as morphological structure is concerned, it should be noted that they lack an envelope and have a diameter of about 50 nanometers. It is an extremely simple virus, since a single protein (L1) is sufficient for the complete formation of the capsid that protects the genetic information of the pathogen. There is another coat protein (L2) much less abundant, which still has functions not fully described.

Because the capsid-forming proteins of all papillomaviruses are antigenically similar, These viruses cannot be cataloged into different serotypes (that is, according to the antigens on the surface mobile). Thus, the subtypes described are based on the differences in the DNA double helix (for example, HPV 16 or HPV 1). It should be noted that for a specific virus to be considered a subtype, the genetic difference with respect to its peers must be 2 to 5%.

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A diverse pathogenesis

Once we have made a concrete mental image of this problematic pathogen, it is essential that we divide human papillomaviruses according to their dangerousness, that is, whether they are oncogenic or not. Go for it.

1. Cutaneous HPV

If any of the readers, when observing a wart on her body, thinks that he is dealing with a skin lesion due to trauma, he is wrong. It is surprising to know that warts form from HPV infection, yes, completely different subtypes from those that cause cervical cancer (in most cases).

So that, we can see common, flat, palmoplantar warts, etc. These respond to various papillomaviruses: HPV 1, HPV 2, HPV 3, HPV 4, HPV 26, HPV 41 and a very long list of numerical concatenations. In the vast majority of cases they are ubiquitous and asymptomatic infections, that is, widely distributed and that do not cause any harm, since they resolve themselves throughout weather.

This type of infection can affect up to 10% of children and adolescents, and the virus penetrates the epidermis and spreads spreads by autoinoculation, causing this characteristic formation that can last up to 18 months after infection primary. Of course, in the world of warts there is nothing to worry about.

• You may be interested in: "The 5 most important types of warts"

2. Genital HPV

Here things get complicated. It is necessary to limit that the vast majority of genital HPV infections in young women are temporary and of little long-term significance. To the relief of any reader, 70% of infections clear up on their own in one year, and 90% within two years. Even so, it is necessary to report the atypical, and it is that potentially oncogenic HPVs are found in this group.

Unfortunately, the HPV 16 and HPV 18 subtypes are responsible for 70% of cervical cancers and precancerous lesions in this same area. Although in most cases this type of infection is self-resolving, in a small percentage of the population it is become permanent conditions, which can turn normal cells into precancerous lesions or Cancer.

Of the more than 150 types of human papillomavirus, about 14 are considered oncogenic., but unfortunately HPV infection is the most common STI in the world. Therefore, it is estimated that in 2018 some 311,000 women died directly from the infection. More than 85% of deaths occurred in low- and middle-income countries. We are not only dealing with the female gender from a binary point of view, since oncogenic HPVs have also been correlated with cancer of the penis, anus, head and neck.

It should be noted that not all genital infection-forming HPVs are high-risk. For example, HPV 6 and 11 are correlated with the majority of wart occurrences on organs. but they are considered to have a low cancer risk, since their chances of generating cancer in humans it is low.

A cosmopolitan layout

Covering the symptoms and treatment of human papillomavirus is virtually impossible, since the existing subtypes manifest in different ways and the transmission methods are diverse (although they combine in the production of warts, for example).

We see much more interesting, in this case, to perform a global map of this viral family and contextualize it from a population point of view. Go for it:

• HPV 16 (unfortunately high risk) is the most common subtype in the world, with the exception of Indonesia and Algeria, where HPV 18 reigns.
• The highest prevalence of high-risk oncogenic HPV types 16, 18, 31, 33, 35, 45, 51, 52, 58, 59, is found in Africa and Latin America
• HPV 45 has a high incidence in West Africa.
• Subtypes 33, 39 and 59 are concentrated in Central and South America.
• About 6.2 million American adults or adolescents between the ages of 15 and 44 were infected with genital HPV in 2000.
• At any given time and region, about 30% of women between the ages of 14 and 59 are infected with at least one type of HPV.

From a purely epidemiological point of view we are facing a viral family of a fascinating nature, since its distribution is cosmopolitan and does not understand ethnicity, age or gender. Luckily most infections are harmless, otherwise we would find ourselves facing a serious global problem that is difficult to eradicate.

It should be noted that, due to their exaggerated prevalence, highly effective vaccines have been developed against the HPV 16 and 18 subtypes. Women are recommended to be vaccinated before starting their sexual activity, as this preventive treatment provides little benefit to a person who is already infected.

Resume

As we have seen, we are facing a fascinating (but relatively dangerous) viral family, with so much information and infectious dynamics that a book could be written about it without any difficulty. If we want something to be clear, it is that there are many subtypes of human papillomavirus, most harmless, but a few (at least 14) high risk, due to its potential to generate cancer in the individual.

When any reader analyzes a wart from now on, he will know the truth behind it: a harmless infection. Papillomaviruses are a multifaceted and problematic family of pathogens, but they are still fascinating viruses from an epidemiological point of view.

Bibliographic references:

• What is HPV? Plannedparenthood.org. Picked up on September 16 in https://www.plannedparenthood.org/es/temas-de-salud/enfermedades-de-transmision-sexual-ets/vph
• Human Papillomavirus and Cancer, Cancer.net. Picked up on September 16 in https://www.cancer.net/es/desplazarse-por-atenci%C3%B3n-del-c%C3%A1ncer/prevenci%C3%B3n-y-vida-saludable/el-virus-del-papiloma-humano-vph-y-el-c%C3%A1ncer
• Papillomavirus Infection, Centers for Disease Control and Prevention. Picked up on September 16 in https://www.cdc.gov/std/spanish/vph/stdfact-hpv-s.htm
• Human Papillomavirus (HPV) and Cervical Cancer, World Health Organization (WHO). Picked up on September 16 in https://www.who.int/es/news-room/fact-sheets/detail/human-papillomavirus-(hpv)-and-cervical-cancer
• Rivera, R., Aguilera, J., & Larraín, A. (2002). Epidemiology of the human papillomavirus (HPV). Chilean Journal of Obstetrics and Gynecology, 67 (6), 501-506.