Although ticks are commonly thought of as insects, they are actually arachnids like scorpions, spiders, and mites. All members of this group have four pairs of legs as adults and have no antennae unlike adult insects which have three pairs of legs and one pair of antennae. Ticks are among the most efficient carriers of disease because they attach firmly when sucking blood, feed slowly and may go unnoticed for a considerable amount of time while feeding. Ticks take several days to complete feeding.
Ticks have four life stages: egg, six-legged larva, eight-legged nymph and adult. After the egg hatches, the tiny larva (sometimes called a "seed tick") feeds on an appropriate host. The larva then develops (molts) into the larger nymph. The nymph feeds on a host and then molts into an even larger adult. Both male and female adults find and feed on a host and then the females lay eggs sometime after feeding.
Ticks wait for host animals from the tips of grasses and shrubs (not trees). When brushed by a moving animal or person, they quickly let go of the vegetation and climb onto the host. Ticks can only crawl; they cannot fly or jump. Ticks found on the scalp have usually crawled there from lower parts of the body. Some species of ticks will crawl several feet toward a host. Though ticks can be active all year-round, the risk of human infection is highest in the late spring and summer months.
While at least 15 species of ticks occur in Illinois, only a few of these ticks are likely to be encountered by people: American dog tick, lone star tick, blacklegged (deer) tick and brown dog tick.
The American dog tick is the most commonly identified species responsible for transmitting Rickettsia rickettsii, which causes Rocky Mountain spotted fever in humans. The American dog tick can also transmit tularemia. Dogs and medium-sized mammals are the preferred hosts of adult D. variabilis, although it feeds readily on other large mammals, including humans.
The lone star tick transmits Ehrlichia chaffeensis and Ehrlichia ewingii, causing human ehrlichiosis.The Lone Star tick can also transmit tularemia and STARI. White-tailed deer are a major host of lone star ticks and appear to represent one natural reservoir for E. chaffeensis. A. Americanum larvae and nymphs feed on birds and deer. Both nymphal and adult ticks may be associated with the transmission of pathogens to humans.
The blacklegged tick, commonly known as a "deer tick", can transmit the organisms responsible for anaplasmosis, babesiosis, and Lyme disease. I. scapularis larvae and nymphs feed on small mammals and birds, while adults feed on larger mammals and will bite humans on occasion. It is important to note that the pathogen that causes Lyme disease is maintained by wild rodent and other small mammal reservoirs.
The deer tick has been found sporadically in many Illinois counties.
The brown dog tick can transmit Rocky Mountain spotted fever (Rickettsia rickettsia), canine ehrlichiosis (Ehrlichia canis) and canine babesiosis (Babesia canis vogeli and Babesia gibsoni-like) to dogs. Dogs are the primary host for the brown dog tick for each of its life stages, although the tick may also bite humans or other mammals. The brown dog tick is tropical in origin and does not survive Illinois winters outdoors. The brown dog tick is not considered an important carrier of human disease in Illinois.
While it is a good idea to take preventive measures against ticks year-round, be extra vigilant in warmer months (April-September) when ticks are most active.
Avoid wooded and bushy areas with high grass and leaf litter.
Walk in the center of trails.
Use repellents that contain 20 to 30% DEET (N, N-diethyl-m-toluamide) on exposed skin and clothing for protection that lasts up to several hours. Always follow product instructions. Parents should apply this product to their children, avoiding hands, eyes, and mouth.
Use products that contain permethrin on clothing. Treat clothing and gear, such as boots, pants, socks and tents with products containing 0.5% permethrin. It remains protective through several washings. Pre-treated clothing is available and may be protective longer.
Other repellents registered by the Environmental Protection Agency (EPA) may be found at cfpub.epa.gov/oppref/insect/.
Bathe or shower as soon as possible after coming indoors (preferably within two hours) to wash off and more easily find ticks that are crawling on you.
Examine gear and pets. Ticks can ride into the home on clothing and pets, then attach to a person later, so carefully examine pets, coats, and day packs.
Tumble clothes in a dryer on high heat for an hour to kill remaining ticks. (Some research suggests that shorter drying times may also be effective, particularly if the clothing is not wet.)
IDPH Common Ticks, available at
www.idph.state.il.us/envhealth/pccommonticks.htm (Accessed 9-22-14).
CDC Ticks, available at www.cdc.gov/ticks (Accessed 9-22-14).