Garlic as a tick repellent.

In their Research Letter, Ms Stjernberg and Dr Berglund1 documented a repellent effect of garlic against an unnamed species of tick and stated that daily consumption of 1200 mg of garlic was an alternative to “other agents that might have more adverse effects.” Based on the design of their study, any conclusions concerning the relative effectiveness and safety of garlic as a tick repellent are unfounded. They compared garlic to a placebo, not to other currently available repellents, and they did not present any data on the comparative safety of garlic vs other repellents. The study by Stjernberg and Berglund raises 2 additional questions. First, does garlic effectively repel other arthropods of medical importance? Troops frequently are at risk of attack by several arthropod taxa and need a repellent that is broadly effective. The DoD Repellent System is extremely effective in repelling a number of arthropods in addition to ticks.4 Second, how difficult is it to ensure compliance with a daily regimen of 1200 mg garlic? That is, do troops find garlic acceptable, and can they be relied on to remember to take daily doses? Treatment of uniforms with permethrin can provide repellency for the life of the garment while requiring no action on the part of the wearer.4 For troops and other populations at high risk for arthropod bites, the use of DEET and permethrin remains the most effective and safe method of protection. In fact, consumption of garlic appeared to be only marginally better than doing nothing at all to prevent tick bites. By contrast, treatment of clothing with permethrin, a synthetic pyrethroid, has been shown to be 100% effective against Ixodes scapularis,2 the vector of Borrelia burgdorferi in the northeastern United States, and to provide nearly 100% protection against Amblyomma americanum and Dermacentor variabilis.3 Diethyltoluamide (DEET)-based repellents also are effective in repelling ticks2 and can be applied to skin, as well as to clothing. The US Department of Defense (DoD) promotes the concurrent use of a 33% DEET-based lotion on exposed skin, treatment of uniforms with permethrin, and proper wearing of the uniform. This strategy has been termed the DoD Repellent System and is believed to be the most effective method for reducing the risk of arthropod bites.4 Chad P. McHugh, MPH, PhD Air Force Institute for Environment, Safety and