Sir Francis Bacon is said to have cured his warts by rubbing them with pork fat. The fat was hung in the sun and five weeks later, after the fat had melted away, his warts were gone. Huckleberry Finn favored rubbing warts with a dead cat, while Tom Sawyer thought the best medicament was stagnant water from a dead tree. Other popular historical treatments have included paying vagrants to carry the warts away and rubbing the warts, without being observed, on the father of an illegitimate child.
Our modern understanding of warts began in the 1890s, when it was first demonstrated scientifically that warts were contagious. In 1907 warts were shown to be the result of a viral infection when a researcher developed warts after injecting himself with wart tissue material filtered so finely that only a virus could have passed through. Today, researchers have found that there are more than 50 different types of wart virus (known as human papillomavirus, or HPV) and that each type produces different forms of warts and on different parts of the body. Indeed, new HPV types are continually being identified and there is now, say Alexander and James Berman, of the Medical College of Wisconsin, a previously unparalleled scientific interest in warts.
A good deal of this interest stems from the discovery that several types of wart virus, particularly those known as HPV 16 and HPV 18, are highly associated with certain cancers. These HPV types cause warts on the genitalia, and in women infection with HPV 16 and 18 is so closely linked with cancer of the cervix that researchers now consider them the probable cause of most cases of cervical cancer–the second most common form of cancer in women. Genital HPV infections (which may or may not produce visible warts) have also been found to be highly contagious, being passed between sexual partners as often as two-thirds of the time. Genital wart infections, if suspected, should always be brought to a physician’s attention for proper diagnosis and treatment.
In contrast, common warts are generally harmless and are far less contagious than genital warts. Such warts are most likely to occur on the hands, soles of the feet and shaved areas of the face, where cuts or breaks in the skin make it possible for wart virus particles to reach the deep, living layers of the skin where they are able to reproduce. A person’s susceptibility to warts also depends on the functioning of his or her immune system. For instance, people given drugs that suppress their immune system frequently develop warts. Similarly, children are more prone to warts than the elderly, perhaps because older people have had the chance to develop a stronger resistance to wart virus infections as a result of repeated exposures over the years.
Studies show that 20 percent of all common warts disappear on their own within three months of first appearing and that two-thirds do so within two years. This happens because the body’s immune system finally overcomes the wart virus infection, which helps to explain the apparent success of many folk remedies: most warts will eventually go away no matter how they are treated. Accordingly, experts say that when common warts are treated (for reasons of aesthetics or comfort), the method chosen should cause the least possible pain, scarring and expense.
Common warts can often be successfully treated with one of the many wart medications available without prescription. Most of these preparations contain salicylic acid, which works in part by causing the hardened wart tissues to soften and slough off. An article in the journal Drugs points out that though over-the-counter wart products are able to cure some 80 percent of common warts, their effectiveness depends greatly on their “correct and sufficient applications.”
For warts that are persistent, painful or in sensitive areas, a variety of treatment techniques are available to physicians. Among the more commonly used are repeated freezings with liquid nitrogen, surgical removal (this method is not highly recommended by experts, in part because up to 30 percent of all warts removed surgically recur) and treatment with drugs applied either on top of the wart or injected directly into it. Just as with over-the-counter treatments, these methods all require persistence. In one report, for instance, a three-year-old wart on the sole of a man’s foot was finally eliminated only after weekly freezings had been continued for five months. Other techniques include laser vaporization, hypnosis (which may work by stimulating the body’s immune resources), injection with interferon, and contact immunotherapy, in which a person is first allergically “sensitized” to a chemical which is then applied to the wart, provoking a heightened immune reaction in and around the wart.
Still other warts treatments are now being studied, including a salicylic acid skin “patch” designed to alleviate the inconvenience associated with traditional paints and pastes. And there is even the possibility, say the Bermans, that recombinant DNA technologies will one day make it possible to develop a vaccine to prevent warts and the viral infections that cause them.