WART REMOVERS
Common cutaneous warts are hyperkeratotic papulonodules that most often appear on the hands, arms, and legs of an individual. The Latin word for wart is verruca, meaning “little hill” or “eminence.” Of all the diseases that plague humankind, warts are thought by many to possess the highest number of folk remedy treatments. Throughout history, treatments for warts included application of plant extracts (e.g., willow bark), paring with a sharp penknife, burning with the ash of wine lees, use of corrosives (e.g., brimstone), and rubbing with pork fat, potatoes, green walnuts, broom straws, or intestines of black chickens. Ointments were often rubbed on warts and consisted of a variety of substances, such as dandelion juice, castor oil, and onion juice. Other types of treatments included rubbing warts with the blood of frogs or pigs, or with new pennies, or tying slugs to the wart. Most cures for warts, however, were based on the theory of transferring the warts to another person, animal, or object. While early eighteenth-century thought suggested that warts might be “congealed nutritious juices” that had seeped from damaged underlying nerve filaments up through the skin, it was not until the end of the nineteenth century that the infectious nature of warts was recognized. Soon afterward, in the early twentieth century, it was suggested that warts were caused by a virus, and by the 1950s, confirmation of this theory was possible with the visualization of virus particles using the electron microscope.
Warts are common, contagious, and usually benign proliferations of skin and mucosa caused by human papillomaviruses (HPV), which are double-stranded DNA viruses. The word papilloma is derived from pa- pilla, meaning pustule or pimple, and the suffix oma, meaning tumor. HPV is widespread in human populations, and currently more than 150 types of HPV have been identified. Thus, infection of epidermal cells with HPV can manifest in benign cutaneous tumors as warts. Warts are filled with overgrown skin cells containing live HPV virus particles. Cutaneous (nongenital) warts are generally classified by their clinical features and morphology (e.g., common, flat, filiform) or location (e.g., plantar [undersurface of the foot]). Warts are usually spread by direct skin-to-skin inoculation of the virus from one person to another. Self- inoculation may also occur, especially with direct cutting of the wart, as any trauma that introduces breaks in the stratum corneum facilitates epi- dermal infection. Interestingly, the virus can resist desiccation, freezing, and prolonged storage outside of host cells. Thus, HPV may remain on and contaminate various surfaces (e.g., clothing, towels, floors, instruments) and subsequently infect scratched or broken skin via direct con- tact. While the incubation period for HPV ranges from one to six months, the latency period is suspected to last three or more years.
Because papillomaviruses are specialized for replication in external epithelia, infection is usually confined to the epithelium exposed to the external environment and does not result in systemic dissemination of the virus. While viral replication occurs in differentiated epithelial cells in the upper epidermal layer, viral particles are also often located in the deep epidermal basal layer. The epidermis becomes thickened and hyperkeratotic, and keratinocytes (keratin-containing cells) in the epidermal granular layer become vacuolated as a result of viral infection. The mechanisms by which virions penetrate the stratum corneum and infect viable keratinocytes is poorly understood, as there is a lack of practical in vitro culture systems available for these viruses to serve as study aids.
While the natural history of cutaneous HPV infections is for spontaneous regression within a few months or years, treatments (via medical personnel or the consumer) are frequently used to avoid potential viral spreading, wart enlargement, and individual social discomfort. Home remedies include the use of a pumice stone to remove the callus and/or warm water soaks (forty-five degrees centigrade) for thirty minutes daily for approximately six weeks. Most over-the-counter wart treatments func- tion by chemically destroying the epidermis in which the virus is present and are recommended for the removal of only cutaneous common warts (with typical raised, rough “cauliflower-like” appearance) and plantar warts. These treatments include topical once- or twice-daily application of solutions or pastes containing keratolytic agents such as salicylic acid [2-hydroxybenzoic acid; C6H4(OH)CO2H] and/or lactic acid as an active ingredient. By dissolving the intercellular cement substance, salicylic acid desquamates the horny virus-infected layer of the skin without affecting the structure of the viable epidermis. Treatment duration with this caustic agent depends on the size of the wart and the degree of skin discomfort tolerable to the consumer but generally requires up to twelve weeks. A flexible collodion (a liquid that dries to a long-acting film) or pad/disc-type product containing 15 to 40 percent salicylic acid is often applied directly to the wart lesion to lengthen chemical action time and allow enhanced chemical penetration into the skin epidermis. Such products can contain additional inactive ingredients such as solvents (e.g., acetone, alcohol, ether), fragrances (e.g., from camphor, menthol), emollients (e.g., polysorbate 80, propylene or polyethylene glycol), preservatives (e.g., quaternium-15, denatonium benzoate), thickeners (e.g., karaya gum base, ethylcellulose), and natural products historically thought to in- crease wart healing (e.g., castor oil, plant extracts derived from willow bark naturally containing salicylic acid). Therapeutic effects are usually enhanced by frequently removing dead surface keratin manually.
