Human papillomavirus: features and associated diseases

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

We are dealing with a viral family that can range from a mild wart that resolves over time to cervical cancer in women. Of course, it is impressive to know that within the same family, different members can cause such diverse problems in humans. 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 over 90% of sexually active people have HPV at some point in their life, that is, virtually all adults are addicted. Incredible, right? Below, we show you everything you need to know about this versatile viral family.

    What is human papillomavirus? From wart to cancer

    Human papillomavirus infections occur all over the world, which means that no country, ethnicity, age or gender is immune to this infectious agent. Before embarking on the exciting epidemiology of the disease, we briefly describe the causative agent.

    Small but intimidating

    As we said before, the term HPV does not refer to a specific viral species, but to an entire family. However, all pathogens included in this group share a number of characteristics. For example, they are all double-stranded DNA (that is, their genome is made up of DNA) with around 8,000 base pairs. The genome of these pathogens can be divided into an early region (I), a late region (L) and a control region..

    Regarding the morphological structure, it should be noted that they do not have an envelope and have a diameter of about 50 nanometers. It is an extremely simple virus, because only one protein (L1) is sufficient for the complete formation of the capsid which protects the genetic information of the pathogen. There is another much less abundant covering protein (L2), 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 (i.e., according to cell surface antigens). For that, the subtypes described are based on differences in the DNA double helix (For example, HPV 16 or HPV 1). It should be noted that for a particular virus to be considered a subtype, the genetic difference from its peers must be 2-5%.

      A different pathogenesis

      Once we have a concrete mental picture of this problematic pathogen, it is essential to divide human papillomavirus according to their dangerIn other words, whether they are oncogenic or not. Let’s do this.

      1. Cutaneous HPV

      If any of the readers, upon observing a wart on his body, thinks he is facing a traumatic skin injury, he is wrong. It’s amazing to know that warts are formed by an HPV infectionOf course, completely different subtypes of cervical cancer causes (in most cases).

      So, we can see common warts, flat, palmoplantar, etc. These respond to various papillomaviruses: HPV 1, HPV 2, HPV 3, HPV 4, HPV 26, HPV 41 and a very long list of numeric concatenations. In the vast majority of cases, these are ubiquitous and asymptomatic infections, that is, widespread and not causing any harm, because they go away on their own over time.

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

        2. HPV genitals

        Here, things get complicated. It should be noted that the vast majority of genital HPV infections in young women are temporary and not significant in the long term. Much to the relief of any reader, 70% of infections will go away on their own in one year and 90% in two years. However, it is necessary to point out the atypical, and is that in this group are potentially oncogenic HPVs.

        Unfortunately, the HPV 16 and HPV 18 subtypes are responsible for 70% of cervical cancer and precancerous lesions in this same area. Although in most cases this type of infection resolves spontaneously, a small percentage of the population becomes permanent conditions, which can turn normal cells into precancerous lesions or cancer.

        Of more than 150 existing types of human papillomavirus, about 14 are considered to be oncogenic.But unfortunately, HPV infection is the most common STI in the world. Therefore, it is estimated that in 2018, around 311,000 women died from the direct infection. Over 85% of deaths have occurred in low- and middle-income countries. Not only do we evolve in the female sex from a binary perspective, as oncogenic HPVs have also been correlated with cancer of the penis, anus, head and neck.

        It should be noted that not all genital HPV-forming infections pose a high risk. For example, HPV 6 and 11 correlate with most cases of warts in the sexual organs, but are considered to have low cancer risk because their chances of causing cancer in men are low.

        A cosmopolitan distribution

        Covering the symptomatology and viral treatment of human papilloma is virtually impossible, Since the existing subtypes manifest themselves differently and the methods of transmission are diverse (although they bind together during 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 the point of view of the population. Let’s go to this:

        • HPV 16 (unfortunately at high risk) is the most common subtype in the world, with the exception of Indonesia and Algeria, where HPV 18 is prevalent.
        • 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 in a given region, about 30% of women aged 14 to 59 are infected with at least one type of HPV.

        From a purely epidemiological point of view, we are dealing with a viral family of a fascinating nature, as its distribution is cosmopolitan and does not include ethnicity, age or gender. Fortunately most infections are harmlessBecause otherwise we would face a serious global problem that is difficult to eradicate.

        It should be noted that due to its exaggerated prevalence, highly effective vaccines against HPV subtypes 16 and 18 have been developed.

        summary

        As we have seen, we are dealing with 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 there is one thing we want to clarify, it is that There are many subtypes of human papillomavirus, most of them harmless, but a few (at least 14) high risk, For its potential to cause cancer in the individual.

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

        Bibliographical references:

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

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