Ticks are blood-sucking ectoparasites belonging to the order Acarina, class Arachnida. In Japan, eight genera and 46 species are known. Tick bite patients frequently present to dermatology clinics. The main causative species of human tick bites are Ixodes persulcatus and Ixodes ovatus in northern to central Japan, and Amblyomma testudinarium and Haemaphysalis longicornis in western Japan. Tick bites often occur from April to September, particularly in May through July, consistent with the active period for ticks. Although erythema usually does not develop at the tick bite site, a small area of erythema may be seen in some cases. Occasionally, an erythema larger than 50 mm in diameter are formed at the bite site, known as tick-associated rash illness. It is thought that the erythema is a delayed-type allergic reaction to the substances in tick saliva. Repeated tick bites induce immunoglobulin E production against galactose-1,3-α-galactose, one of the substances in tick saliva, which may trigger an immediate allergic reaction. The most reliable method to remove a tick sucking blood is en bloc resection of the tick and surrounding skin under local anesthesia. Insect repellent spray containing icaridin or DEET are effective to prevent ticks from attaching and tick-borne infections. It is important to educate not only dermatologists but also the general public regarding tick bites.
Keywords: allergic reactions; tick; tick bites; tick-associated rash illness; tick-borne infections.
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