Ticks in Arizona
Jeff Schalau, Agent, Agriculture & Natural Resources
University of Arizona Cooperative Extension, Yavapai County
Ticks belong to a group called arachnids and related to spiders and mites. There are hundreds of species of ticks found worldwide and more than 25 species occur in Arizona. Of that number, most people are likely to encounter only a few species. The most common in Arizona is the Brown Dog Tick, Rhipicephalus sangiuneus.
Ticks have four stages in their life cycle: egg, larva, nymph, and adult. Once hatched, a tick needs to have a blood meal before it can develop into the next stage. The larvae, or “seed ticks” are less than 1/16 inch long and have six legs. After a meal of blood it will molt and enter the nymph stage. Nymphs are still small, less than1/8 inch long, and have eight legs. In the final adult stage a blood meal allows the female to lay eggs. She will deposit as many 5,000 eggs and then die. Ticks at any stage of development can live many months without feeding; an adult brown dog tick can survive for as long as two years without a blood meal.
Because ticks feed on blood, they can transmit disease from animal host to animal host, which makes them a health concern. Tick-borne diseases are rare in Arizona, but they can be serious. Different types of ticks transmit different diseases. Rocky Mountain Spotted Fever (RMSF) is the most common tick-borne disease in Arizona, although there are usually less than a dozen cases per year. In Arizona, the brown dog tick can be a “vector,” transmitting the bacteria that cause RMSF from host to host. The brown dog tick is found worldwide. It has adapted to living both indoors and out, so it can survive cold climates by staying inside a house. Its principal hosts are dogs, but if there is a large population, they may also feed on humans.
Control of ticks on pets and in the local environment is the best prevention for RMSF. The Rocky Mountain wood tick, Dermacentor andersoni, can also transmit RMSF. This tick is only known in the very northern part of Arizona in brushy areas. The first symptoms of Rocky Mountain spotted fever are fever, chills, muscle ache, and headache. A spotted rash often develops two to five days later. Early treatment for RMSF is effective. If a tick bite is suspected it should be mentioned to the doctor so the disease can be diagnosed quickly and treated with the appropriate antibiotic.
One other disease of concern is known to be vectored by ticks in Arizona. Tick-Borne Relapsing Fever is very rare, but is transmitted by a “soft tick,” genus Ornithodorus. These ticks are occasionally encountered in rustic cabins and woodpiles. The ticks are night feeders and only remain attached for a short time, 15 to 30 minutes.
Lyme disease is a serious problem in many parts of the U.S. However, as of 2007, no one has contracted Lyme disease as the result of a tick bite that occurred in Arizona. The vector for disease in the west is the Western black-legged tick, Ixodes pacificus. This family of ticks needs high humidity to survive and usually cannot live in the arid Arizona climate. In Arizona the western black-legged tick has a very limited distribution. It is only known in the higher elevations of the Hualapai Mountains and only in late winter and early spring.
If a tick is found on the skin it should be removed immediately. A tick normally needs to be attached for at least several hours before it will transmit disease to its host; so prompt removal dramatically reduces the likelihood of infection. Removal should be done with fine tweezers. Grasp the tick as close to the skin as possible and gently pull it straight up. Do not twist the tick or the mouthparts may break off and be left in the skin. Also be careful not to squeeze the tick’s body, which can cause it to release fluids into the tissue. After removal, clean the bite area with soap and water, disinfect the tweezers and wash your hands. Preserve any tick taken from a human in a small leak-proof container in rubbing alcohol and label with the date, contact information, and area of origin.
There are a number of chemical ways to provide protection for pets, including collars, dips, sprays, shampoo, and “spot-on” methods. Some tick treatments that are suitable for dogs can be toxic to cats. Your veterinarian can provide information on appropriate applications considering the age and health of your pet. The information above was excerpted from the Yavapai County Cooperative Extension publication titled “Ticks in Arizona” by Master Gardener Debbie Allen. The entire publication is linked to the on-line version of this column.
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Link to Yavapai County Bulletin #77: Ticks in Arizona, by Debbie Allen, Yavapai County Master Gardener Click Here
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Last Updated: November 21, 2011
Content Questions/CNovember 21, 2011g.arizona.edu