Lyme disease is on the rise – How about tick repellents? A global view

Ticks are widely recognized as important vectors of a broad range of disease causing agents. Recently, a noteworthy rise of Lyme disease cases has been reported, outlining the timely importance to develop novel and effective acaricides and repellents to reduce host-tick interactions. In this scenario, we provide a concise global view about the available tick repellent compounds, covering both commercially marketed products, with special reference to diethyltoluamide (DEET), ethyl butylacetylaminopropionate (IR3535), icaridin (saltidin) and p-menthane-3,8-diol, as well as promising compounds under investigation in these years. Among the most effective plant-borne repellents, we highlighted the noteworthy bioactivity of -pinene, geraniol, citronellol, carvacrol, thymol, nepetalactone DHN 1 and DHN 2, nootkatone, valencene-13-ol, eugenol, phenylethyl alcohol and cinnamyl alcohol. In the final sections, major challenges to formulate products maintaining their tick repellent power over time are discussed.