CHICAGO - Molluscum contagiosum is a harmless viral skin infection that you don't hear much about until the small, pinkish growths suddenly appear on your child's face, arms and legs.

Then you find out it's actually so darn common that you've likely seen other children affected by the highly contagious virus, while, say, at your local swimming pool.

The good news is that this probably isn't a big deal. Although some reports show that the spread of molluscum contagiosum is increased in pools - which might be why we often see it at this time of year - the U.S. Centers for Disease Control say the virus is more likely spread through shared towels or toys, rather than the water.

Usually, there's no need to treat it. The lesions, which can be itchy, may last between two weeks and four years - the average is two years - but they eventually go away on their own. Still, the CDC suggests covering all visible bumps with watertight bandages before letting a child swim, and avoiding direct contact sports such as wrestling.

You can also try "beetle juice" or cantharidine, under a doctor's supervision, said Dr. Amy Paller, chair of the dermatology department at Northwestern University's Feinberg School of Medicine. "It's as effective as anything except perhaps scraping each one individually, which is bloody and can be painful," she said.

Cantharidine, a powerful chemical extract derived from a beetle, has been used by the Chinese for thousands of years for a number of maladies. When the physician applies it to each molluscum, it creates a blister that can crust and disappear within a week.

But like other treatments - freezing, draining the fluid or using lasers or creams - beetle juice doesn't trigger the immune system to clear the molluscum, which is what ultimately happens when they spontaneously vanish, said Paller. You can kill out the old lesions, "but new ones could pop up elsewhere or even in the same general area if they were 'incubating' at the time of treatment," Paller said.

Do not buy beetle juice or other "cures" over the Internet because they could be dangerous if not administered by a trained individual, Paller added.

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"Safe" pesticides cause poisonings. Pesticides called pyrethroids, commonly used to control insects in the home, on pets and on people, are generally believed to be less toxic than organophosphates, which were derived from nerve gas. But how safe are they?

"Perils of the New Pesticides," an important investigation by the Center for Public Integrity, shows that pyrethrins and pyrethroids were responsible for a quarter of serious (and sometimes fatal) incidents involving pesticides in the United States in 2007, "up from just 15 percent in 1998 - a 67 percent increase."

CPI, a Washington-based watchdog group, analyzed adverse reaction reports filed with the EPA by pesticide manufacturers, a database that hasn't been public until now. The EPA did not specify whether poisonings were caused by ingestion, inhalation or direct skin contact.

Pyrethins, which come from flowers, and their synthetic relatives, pyrethroids, can be found in thousands of consumer products, including anti-lice shampoos, flea collars and bug repellents. Some municipalities, including the North Shore Mosquito Abatement District, spray for adult mosquitoes with a product called Anvil (sumithrin), which contains pyrethroids. (The EPA says that, unlike insects, humans and other mammals have the ability to break down pyrethroids.)

To look up poisonings in your hometown related to certain chemicals or products, go to publicintegrity.org/investigations/ pesticides.