| Arthropod Repellents |
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 | Arthropod Repellents |  |
Globalization and increased travel continues to spread disease vectors and subject people to biting arthropods and disease. For example, west Nile fever (transmitted by Culex pipiens; Diptera: Culicidae) made its U.S. debut in New York City in 1999; the Asian tiger mosquito, Aedes albopictus (Culicidae; a potential vector of dengue and Japanese encephalitis), is established and spreading in the U.S.; and reports of Lyme disease (transmitted by the deer tick, Ixodes scapularis) have increased dramatically since the first recognized U.S. cases in 1975. Moreover, disease organisms are becoming resistant to drugs, vaccines are lacking for many diseases (e.g. dengue and malaria), and drugs used to treat exotic diseases often have serious adverse side effects. Thus, the demand for arthropod repellents is increasing, yet public and military acceptance, usage compliance and confidence in DEET (by far the mainstay of repellents) has suffered because of concerns about health risks associated with the compound.
The ICEL has a long history of working with the DoD on arthropod repellents. Most recently, a new, more efficient method for quantitative evaluation of candidate repellent compounds using human test subjects has been developed. Using this new methodology, stereoisomers of 1-[3-cyclohexen-1-ylcarbonyl]-2-methylpiperidine, the racemate of which was previously shown to equal or exceed the arthropod repellency of DEET (N,N-diethyl-3-m-toluamide), were synthesized and tested. The stereoisomers differ significantly (but in the same relative pattern) in repelling Anopheles stephensi and Aedes aegypti (Culicidae), mosquito vectors of yellow fever and malaria. This is the first demonstration, to our knowledge, of differential repellent activity of a compound based on chirality.