Non-sexually Acquired Human Papillomavirus Infection - An Overview

Introduction:

Human papillomaviruses (HPVs) are viruses that do not have an outer coating and carry genetic material. There are over 200 kinds of HPVs. All types of HPV are attracted to and infect the squamous epithelial cells found in the skin and mucous membranes. HPV infections are very common. In the United States, about one percent of sexually active adults and three percent of sexually active teenagers have them. Every year, around 14 million people get infected, and a whopping 79 million have had an HPV infection at some point.

What Is Non-sexually Acquired Human Papillomavirus Infection?

Human papillomavirus (HPV) is a tiny virus of DNA (deoxyribonucleic acid) that comes in many types. Over 200 of these viruses have been identified so far. Each type infects a specific part of the body and causes different symptoms. Non-sexual HPV transmission happens when infected skin or skin cells touch broken or moist skin directly. HPV is thought to trigger about 99 percent of cervical cancers, 90 percent of anal cancers, 65 percent of vaginal cancers, 50 percent of vulvar cancers, and 45 to 90 percent of oropharyngeal cancers.

What Are the Various Modes of Transmission for Human Papillomavirus Infection?

HPV is commonly transmitted through sexual contact. This mode of transmission is well-documented, particularly in the spread of sexually transmitted infections.

Other modes of transmission are mentioned below:

1. Horizontal Transmission - This mode of transmission refers to the spread of HPV through non-sexual means. This can occur through various routes:

• Direct Contact: HPV can be transmitted through direct skin-to-skin or skin-to-mucosa contact. While sexual contact is the most studied form of direct transmission, studies suggest other potential sources of direct contact transmission.

• Contaminated Surfaces and Equipment: HPV can survive on surfaces and equipment for days. Contaminated gynecological equipment and medical settings have been identified as potential sources of HPV transmission, especially in private practices.

• Self-inoculation: Self-inoculation refers to the transmission of HPV from one part of the body to another. Studies have found HPV DNA on the fingers and under the fingernails of infected individuals, suggesting the possibility of self-inoculation.

2. Vertical Transmission - Vertical transmission occurs when HPV is passed from mother to newborn. This can happen during childbirth through exposure to infected genital mucosa or amniotic fluid. Studies have shown that HPV infection prevalence among pregnant women is low but can lead to transmission to newborns.

3. Waterborne Transmission - Although waterborne transmission of HPV has not been definitively proven, studies have identified HPV DNA in water habitats such as sewage and rivers. HPV in sewage and swimming water suggests a potential waterborne transmission route, although further research is needed to confirm this hypothesis.

Who Develops Human Papillomavirus Infections Through Non-sexual Means?

HPV infections without sexual contact are common among:

• Children and young adults.

• Workers who handle meat, poultry, and fish sometimes lead to 'butcher warts' caused by HPV 7 (human papillomavirus type 7).

Extensive and long-lasting HPV infections are often linked with:

• Weakened immune systems, such as in individuals with HIV (human immunodeficiency virus) infection or AIDS (acquired immunodeficiency syndrome) or those who have had organ transplants and are taking immune-suppressing medications.

• Atopic dermatitis (a skin condition characterized by inflammation and itchiness).

What Are the Causes of Non-Sexually Acquired HPV Infections?

Non-sexual HPV infections are usually caused by certain types of HPV, such as 1, 2, 3, 4, 7, and 10. These types commonly lead to warts on the skin, including common, flat, and plantar warts.

Examples of how non-sexual HPV infections can happen include:

1. The virus spreads to other body parts through touching a wart, especially in children.

2. Passing the virus from a caregiver's hand to a baby during a diaper change.

3. Transmitting the virus from a mother to her baby during childbirth.

How Do Non-sexually Acquired Human Papillomavirus Infection Appear Clinically?

When someone gets infected with HPV on their skin, they might develop a visible bump called a wart. Sometimes, the infection is not visible but persists, making the skin look normal. It can take up to a year for warts to appear after being infected, as demonstrated in cases where warts emerge a year after an organ transplant or after scientists inject wart tissue to observe its spread.

Non-sexual HPV infections manifest differently depending on their location on the body and their appearance. Warts can appear as a single bump or multiple bumps, often in lines, because the virus spreads when one touches them and then touches another part of the skin.

Do Everyday Hygiene Practices Prevent HPV Transmission Effectively?

Regular hygiene practices may not effectively prevent HPV transmission. Studies examining HPV samples on contaminated medical equipment after standard disinfection have shown the continued presence of the virus, particularly type 16. There is limited research on the resistance and susceptibility of HPV type 16 to common disinfectants.

However, one study indicated that HPV 16 is resistant to alcohol-based disinfectants like ethanol and isopropanol but sensitive to hypochlorite and high concentrations of peracetic acid-silver-based disinfectants. This suggests the potential for self-inoculation and horizontal transmission of HPV. It highlights the need for updated disinfection protocols for healthcare equipment.

Simple steps to reduce the risk of non-sexually acquired HPV infection transmission include:

• Do not touch warts unnecessarily.

• Do not share tools, like nail files used on a wart.

• Try not to shave areas with warts, especially on the face, if someone has warts there.

• Wear shoes in public places, like showers, to avoid contracting the virus.

How Are Non-sexually Acquired HPV Infections Diagnosed and Treated?

Dermoscopy can show round keratin structures with red or black dots indicating blood vessels. Sometimes, a skin biopsy might be needed, especially if there is a rough lesion that looks like it could be squamous cell carcinoma (SCC), especially in people who have had organ transplants. Warts have certain features that can be seen under a microscope, which doctors can check for.

Various treatments are available for warts:

1. Topical treatments include:

• Podophyllotoxin and Podophyllin can induce wart necrosis (with a recurrence rate of 38 percent).

• Imiquimod (an immunomodulator).

• Polyphenol E (derived from green tea extract).

2. Intralesional immunotherapy involves injection with antigens such as candida, mumps, or trichophyton skin test antigens.

3. For treating conditions caused by HPV infections, such as warts, systemic treatments can include medications like Interferon and Isotretinoin.

Other treatments include:

• Cryotherapy: Freezing the wart with liquid nitrogen is a common treatment. It needs to be done multiple times, usually soon after the top layer of the wart falls off but before it has a chance to grow back. This treatment can be painful and may cause a blister to form. Other freezing methods, like carbon dioxide snow or spray cans, are usually less effective.

• Trichloroacetic acid causes chemical burns and can cauterize and erode skin and mucosa.

• Potassium hydroxide dissolves keratin and can penetrate the skin.

• Surgical excision.

• Photodynamic therapy.

• Carbon dioxide laser.

Conclusion:

Most skin warts caused by HPV go away on their own in kids within two years. For adults, warts might take longer to disappear and could last for several years. The spread of HPV without sexual contact is an important but sometimes forgotten part of HPV infection. Proper education, vaccinations, and good hygiene are all important parts of effective plans to fight HPV infections that are not spread through sex. These measures help lessen the impact of non-sexually acquired HPV infections on people and healthcare systems.