Update: While many believe mosquitoes disappear in the fall months, all you need to do is take a walk along the shores of Utah Lake or the Great Salt Lake to see that isn't the case. And with cases of West Nile virus still being reported in the United States — and with its expected arrival in Utah in the near future — questions about which insect repellent to use are continually being asked.
According to a recent report in the New England Journal of Medicine, researchers at the University of Florida tested a variety of widely available insect repellents — including some botanical products — to determine which ones provide the best protection. Their study overwhelmingly showed that products containing N,N-diethyl-3-methylbenzamide (DEET) are the most reliable and protective.
Products containing different concentrations of DEET were tested, and researchers found that high doses resulted in longer-lasting protection. The only botanical repellent that came close to the efficacy of the lowest concentrations of DEET was one containing soybean oil. Products containing eucalyptus oil were introduced after the study was completed, and initial evaluation suggests that among botanical products, those products may offer the longest-lasting protection.
The researchers concluded that products containing DEET— rather than botanical preparations — should be used in areas where diseases, such as malaria, encephalitis or West Nile virus, can be transmitted in a single bite.
In the United States, DEET is sold in concentrations from 5 percent to 100 percent in lotions, solutions, gels, sprays and towelettes. While higher concentrations provide longer-lasting protection, for most uses there is no need to use the highest concentrations of DEET. Products with 10 percent to 35 percent DEET provide adequate protection.
The American Academy of Pediatrics currently recommends that repellents used on children contain no more than 10 percent DEET. The chemical has been found to be just as effective when applied to clothing as opposed to skin.
Products with a DEET concentration over 35 percent are probably best reserved for environments with a very high density of insects (e.g., a rain forest), where there is a high risk of disease from insect bites, or conditions that wash the repellent from the skin (e.g., rain or high temperature and humidity).
Update: Acute knee injuries (caused by being hit or twisted) are a common problem, accounting for 1.3 million visits to emergency rooms in the United States.
The Ottawa Knee Rules, developed and studied by a group of emergency physicians in Ottawa, Canada, are a set of criteria that help an emergency physician decide whether or not to obtain an X-ray in a patient with a knee injury. The goal is to reduce the number of unnecessary X-rays, yet never miss a fracture.
When correctly applied, the rules significantly decrease the number of normal (negative) knee X-rays ordered, yet still have a 100 percent rate for detecting fractures.
Specifically, the Ottawa Knee Rules apply only to those with an acute-knee injury with any of the following:
Age 55 years or older
Tenderness at head of fibula
Isolated tenderness of the kneecap (patella)
Inability to flex the leg to 90 degrees or
Inability to walk four steps both at the time of injury and hours later
If any of the above exists, the person should be seen by a physician because the knee is likely broken.
This test has been reported in several medical journals and will primarily be used by emergency physicians. However, the lay first aider might use the rules to help determine whether the knee is broken.
Then, depending upon the results, the person can either seek medical care (if a severe injury is suspected), or care for it by staying off of the injured leg, applying an ice pack (20 minutes at a time every three hours), applying a wide(4-inch to 6-inch) elastic bandage when the ice pack is off and keeping the leg elevated. All these should be done for 48 hours after an injury. If the injury does not improve, seek medical care.
Alton Thygerson, professor of health sciences at Brigham Young University, is the National Safety Council's first aid and CPR author and technical consultant.