What are warts — and how do you get rid of them?

Throughout history, people have attributed

warts to contact with things like sea foam, boiled egg water,

and, of course, toads. We now know that toads are totally

innocent in the matter. They're bumpy because mucus- and poison-

secreting glands dot their skin. And we've figured out that warts are

actually caused by papillomaviruses. They form a broad virus family that

infects various species, including us. There are more than 200 different types

of specifically human papillomaviruses, or HPVs. As is the case with all viruses,

HPVs can't multiply independently. Instead, HPVs use our skin cells

to replicate. They do this by infecting the basal cells

that constantly produce new skin cells and line the base of our skin's

outermost layer, the epidermis. Your skin is your largest organ. It functions like a waterproof,

active immune barrier that protects your body

from the many pathogens perpetually poised to penetrate it. If any HPVs do make it past the skin's

outermost surveillance system, it can activate a barrage of defenses. But sometimes, HPVs still make it through. They have a better chance of getting all

the way to the skin's basal cell layer when your skin is wet, softened,

or injured, even with the tiniest of cuts. You're most likely to develop warts

on your hands and feet because they're most likely

to encounter foreign surfaces and get superficially injured, especially in shared, wet environments

like shower rooms. Once HPV reaches your skin's

basal cell layer, it unleashes its genome, which instructs the basal cells

to multiply at higher rates, defer cell death,

and replicate the virus. From there, the infected

skin cells proliferate, piling up as they move towards

the skin's surface, forming that telltale wart. But what exactly the wart looks

like depends on a few factors. It's not totally clear why, but different HPV types tend to infect

different parts of the body, cause unique-looking warts,

and range in seriousness. Common warts are often domed

and found on hands, elbows, and knees; plantar warts occur on the soles of feet,

where walking may flatten them; filiform warts, around the mouth and eyes;

and flat warts, on the legs and face. Warts can also feature little black dots, which are actually tiny blood clots

where capillaries in the skin have become obstructed. Regardless of how exactly the wart forms, when the infected skin cells

it's made of die, they release thousands of HPVs. This is why one wart can theoretically

infect other parts of someone's body— or other people, directly or indirectly. However, the likelihood of this happening

depends on what kind of HPV is involved and what part of the body

it's best at infecting. Most HPVs infect different areas of

the skin and cause benign warts. However, some HPVs prefer

the body's mucosal epithelia, the soft, moist tissues that line our

reproductive, digestive, and respiratory tracts. These HPVs are the most common sexually

transmitted infections. And while they're also usually benign,

they're more likely to be persistent and some types can cause cancers. Doctors might recommend topical

or surgical treatment for these infections. And HPV vaccines that are almost

100% effective in preventing infections from the riskiest HPV types

became available in 2006. The body often keeps HPV at bay or resolves infections

within a couple of years. But some people are more susceptible,

and some HPV types are more persistent. Handling meat and fish puts people

in contact with specific HPV types. Children and elderly people are thought

to be more vulnerable to HPV infections because their skin tends to be thinner

and have less organized immune defenses. And compromised immunity or skin flora— caused by things like smoking,

chemotherapy, HIV, and genetic variation— can make it harder for the body

to suppress HPV infections. And although most warts are harmless

and go away without intervention, they're still contagious, and dermatologists have methods

to help the body clear them. Some treatments work by stimulating

the immune system directly, while others— like salicylic acid

and cryotherapy— irritate the infected area,

indirectly activating an immune response. Thankfully, there are lots of options

available in addressing our wart worries— and simply no need to slander toads.