Newswise — West Nile virus is present in almost every corner of our country and this is the peak season. A new analysis from the Centers for Disease Control and Prevention on U.S. West Nile virus cases in 2007 found that most (89%) of the 3,630 cases were reported during July, August and September. All but six states reported cases of WNV infections in humans last year. The CDC says the mosquito-borne disease is underreported and under-diagnosed and estimates that approximately 175,000 Americans may have been infected with West Nile last year. There are at least 44 confirmed cases of WNV across 15 states so far this year.
The CDC and state and local public health agencies nationwide recommend the use of EPA-registered insect repellents to help protect against West Nile virus. The most popular of these recommended repellents is DEET, which is used by at least one-third of Americans every year. Despite its popularity, or perhaps because if it, many myths persist about DEET.
Myth: No more than 10% DEET should be used on children. Fact: Federal regulators say that all concentrations can be used by people of all ages when label directions are followed. The American Academy of Pediatrics says products containing up to and including 30 percent DEET can be used on children two months of age and older. The AAP also says that products containing DEET are among the most effective repellents available and should be used when necessary to protect against bites from insects and ticks that may carry disease.
Myth: Some popular skin creams and "natural" repellent products are safer than DEET. Fact: "DEET has been shown to be an extremely safe and effective repellent," said Lyle R. Petersen, M.D., director of the CDC's division of vector-borne infectious diseases. University of Florida scientists Jonathan Day and Roxanne Rutledge wrote: "Natural is a word that is sometimes used to promote 'safe' products. Unfortunately, the wording can be misleading for the uninformed individual. 'Natural' products are usually essential oils distilled from plants"¦ These oils can be toxic and irritating in high concentrations. 'Natural' repellents are not necessarily safe repellents." DEET is one of the most widely tested consumer products of any type and has been used reliably by consumers for more than 50 years. According to a New England Journal of Medicine article (Fradin & Day, 2002), DEET "has a remarkable safety profile."
Myth: Garlic, bananas and vitamin-B ward off mosquitoes. Fact: "There is no scientific evidence that eating garlic, vitamins, onions, or any other food will make a person repellent to mosquitoes," said Day and Rutledge of the University of Florida. "It is also unlikely that B-1 skin patches will work either," Day says. DEET is regarded as the "gold standard" against which other repellents are tested.
Myth: New devices are effective against mosquitoes. Fact: "There is no evidence that wearing devices that emit sound will repel mosquitoes," say Day and Rutledge. "Bug zappers do not control mosquitoes and can reduce the populations of beneficial insects," says Ken Gioeli, University of Florida natural resource agent. Some experts suggest that zappers actually attract mosquitoes to your property.
Myth: Dryer sheets and other home remedies repel bugs. Fact: "The truth is although many home remedies and oddball uses of everyday products do serve to repel mosquitoes somewhat, they don't work very effectively for very long," writes Barbara Mikkelson on the popular Web site, www.snopes.com.
Myth: DEET is smelly and oily. Fact: Fifty years of product development has yielded DEET-based products that are pleasant to use—they have a pleasant "feel" on the skin and fresh fragrances. Some even go on as a dry formulation similar to spray deodorant that is powder-like.
Myth: Higher concentrations mean better protection. Fact: Higher concentrations of DEET mean longer protection, not better. A 5% product will provide about 90 minutes of protection and a 100 % product protects for about 10 hours. Protection time increases as the concentration increases. So, the longer you are outside, the higher the concentration you should use. However, protecting against ticks requires at least 20% DEET, and no other repellent works as well against ticks.
Most folks who are going outside for a backyard barbecue should choose a product that protects them for up to two hours, a repellent in the 10% range. It's often fine to use a concentration below 30% for most outdoor activities. When you are exposed for long periods to hoards of mosquitoes, though, a 100% product is advisable.
Myth: I don't need repellent unless I'm headed out into a wooded or waterfront location. Fact: Mosquitoes can be anywhere, even in a city, and many carry disease. Most people who have contracted WNV were bitten by mosquitoes lurking in their own yards. Cases of malaria have occurred in recent years in Washington, D.C. And other mosquito-borne diseases sometimes occur elsewhere in the United States.
Myth: DEET is an insecticide. Fact: DEET does not kill mosquitoes, as insecticides do. It repels them by confusing their ability to locate humans.
Myth: DEET causes seizures in children. Fact: Scientific reviews do not show a causal relationship between DEET and seizures (Murphy, et al, 1997; Bell, et al, 2002). This myth stems from a handful of isolated reports in both adults and children that cannot be definitively linked to DEET. Experts report that two percent of typical children have one or more seizures from unknown causes by age 10. A multi-year review of adverse events yielded a handful of neurological cases (given millions of product uses per year) that could not be tied to use of DEET-based repellents. These neurological adverse events were not more common in children than in other age groups and were not tied to concentration of DEET in the products.
Myth: Some popular skin creams and "natural" repellents work as well as DEET. Fact: Scientifically controlled studies show very few repellents are effective as DEET (Fradin & Day, 2002). The CDC urges consumers to pick only repellents with EPA registrations to assure appropriate efficacy. The most effective, according to the CDC, are DEET, picaridin, oil of lemon eucalyptus (recommended with limitations) and IR3535 (www.cdc.gov).
[Journalists: Photos of mosquitoes and ticks and more information is available by calling 215-504-2035.]