A prevalent sexually transmitted virus may be silently residing in the feet of millions of Americans, unnoticed but potentially leading to discomfort and serious health issues if ignored.
Human papillomaviruses (HPV) consist of over 200 different strains. Some high-risk types are sexually transmitted and can result in cancer, while others, considered low-risk, can be picked up from contaminated surfaces and cause stubborn warts.
HPV infections in the genital area often go undetected due to the absence of symptoms, yet they pose a future cancer risk. Fortunately, this risk can be significantly minimized with vaccination.
Although HPV is primarily recognized as a sexually transmitted infection, it can manifest on the feet as what is known as a verruca or plantar wart.
This particular strain, though less severe, can remain asymptomatic. However, similar to its sexually transmitted counterpart, ignoring verrucae can lead to significant problems.
These warts can penetrate deeply into the skin, resulting in pain, walking difficulties, rapid spread across the body, and potential secondary infections.
I see dozens of patients a week dealing with the unfortunate effects of warts, including one who was so worried about the possibility of the virus spreading across his foot that he followed an intensive treatment regimen for a month.
And an avid biker who came to see me was so concerned about the pain and size of the verruca on his heel that he instantly opted for microwave therapy to attempt to blast the virus.
While HPV is most known as an STD, when it shows up on your feet, it is called a verruca, or plantar wart (stock image)
What is a verruca?
Although benign, HPV verruca is highly contagious and relies on water to survive.
The bottom of our feet is the perfect location for this unassuming virus to penetrate small cuts, splits or wet damaged skin.
Once the virus enters and infects the top layer of skin it creates a reaction that triggers the overproduction of hard skin.
Pressure on this area of skin from walking causes the lesion to imbed deeper into the skin, which creates its ‘cauliflower’ appearance.
The infection caused by HPV in the skin of the foot causes small blood vessels called capillaries to clot, creating the black dots associated with the appearance of warts.
The virus uses this environment to survive and infect other parts of the body by entering and exiting the skin in a process called autoinoculation – the spread of an infection from one part of your body to another.
According to recent studies, around ten percent of the US population develops warts on their feet, 20 percent of these are school-aged children.
Recent studies have suggested that HPV infection of the foot is more common in women than men, and immunosuppressed individuals at higher risk.
How does HPV infect the foot?
Around ten percent of the US population develops warts on their feet (stock image)
Communal areas such as locker rooms, swimming pools and gyms are some of the most frequently associated places with HPV presence.
Small cuts and cracks in the skin are prime targets for the virus to enter undetected.
Scratching is a habit that not only creates targets for HPV infection, but also contributes to the spread of the virus to other parts of the body. As skin sheds, so does the virus, spreading across surfaces with ease.
There are approximately 250,000 sweat glands in our feet, so a dark, warm, moist environment allows HPV to survive outside the skin and re-enter when the skin is soft and more susceptible to infection.
Physical pressure can increase the likelihood of verrucae, as walking barefoot exposes the bottom of the foot to damp surfaces that suit HPV and can cause existing verrucae to grow inward, potentially causing more pain for those affected.
Contaminated objects such as shoes, socks and towels can be a higher risk for infection.
The key is to avoid use of garments or towels belonging to other people. Using your own shoes, socks and towels is crucial to minimizing the risk of HPV infection in the foot.
How would a verruca affect me?
Zinc oxide tape is a common treatment that covers the lesion to prevent its spread (stock image)
Many affected individuals do not even realize they are infected until the lesion appears. It can be months before the verruca is visible, and once the lesion appears it may take months or sometimes years to eventually disappear.
Pain and swelling during standing or walking can be felt by affected individuals.
Jonathan Brocklehurst (pictured) is a podiatrist based in the UK
HPV viral infection not only affects the standing and walking abilities of individuals, but can have a detrimental effect on mental health, especially when it comes to aesthetic self-consciousness in social group environments.
Major complications from verrucae could be rapidly spreading warts to other parts of the body and secondary bacterial infections caused by picking or scratching the wart.
Worse case scenarios often include severe pain, misdiagnosis of squamous cell carcinoma (cancer) or ulceration in people with diabetes and neuropathy.
If untreated, warts can spread, increase in size and become extremely painful, affecting day-to-day activities like walking.
How is HPV of the foot treated?
Minimally invasive treatments such as cryotherapy and microwave ablation have shown high rates of success of eliminating plantar warts (stock image)
Due to its autoimmune effects, the HPV virus will only become inactive once the immune system detects it and responds by combating infected cells.
Dermoscopy is an important means of assessment that helps podiatrists to confirm whether the lesion is a verruca or not.
It is important to avoid self-diagnosis and self-care until the suspected verruca is assessed by a podiatrist.
Once diagnosed, there are many treatment options for treating HPV infection of the foot.
Zinc oxide tape is a hypoallergenic conservative treatment that covers the lesion to prevent the autoinoculation process.
Topical agents including salicylic and lactic acid can be explored as options, however, existing evidence suggests a success rate of approximately just 30 percent.
More potent minimally invasive treatments such as cryotherapy and microwave ablation have shown higher rates of success, particularly in children and adolescents.
Jonathan Brocklehurst, MSc, MIRL, MRCPod, is a podiatrist based in the UK.
