Houseman, Richard M.

University of Missouri: MOspace

Ticks are close relatives of mites, spiders and scor-pions. Ticks pass through four stages in their life cycle:egg, larva, nymph and adult. All stages except the eggare blood-sucking parasites. Tick larvae hatch from theeggs, are small, have only six legs, and are often calledseed ticks. Immature and adult ticks are most likely tobe encountered in wooded or brushy areas where theirhosts are most abundant, but they can also be found inlawns if their hosts are present there.The larvae and nymphs often feed on smalleranimals and birds. Some nymphs and adults typicallyfeed on larger animals, including humans and theircompanion animals.Ticks locate their hosts by “questing.” During quest-ing, ticks climb to the tips of vegetation and extend theirfront legs out away from their bodies. They hold on tothe vegetation with the remaining legs. Because they aresensitive to drying out, they usually return to the baseof vegetation several times a day to stay hydrated. Aspotential hosts pass by questing ticks, the hooks on theends of the front legs become attached to the host andpull the tick from the vegetation. Once on the host, ticksseek areas to settle, insert their mouthparts and beginfeeding. Ticks will also travel short distances toward acarbon dioxide source to locate potential hosts. The two most frequently encountered ticks inMissouri are the lone star tick, Amblyomma americanum(Figure 1), and the American dog tick, Dermacentorvariabilis (Figure 2). Another species, the brown dog tick,Rhipicephalus sanguineus (Figure 3), may also be commonon domestic dogs. The brown dog tick only feeds ondogs, but may be brought into homes with dogs andbecome an indoor pest. Many other species of ticks canbe found in Missouri, but they come into contact withpeople less frequently.Ticks do not have a true head, only mouthpartsprojecting from the front edge of the body. The size andshape of the mouthparts are often used to identify differ-ent tick species. A tick uses these mouthparts to cut asmall hole in the host’s skin. The mouthparts are theninserted into the host’s tissues to obtain blood. Maleticks have a hard, shieldlike plate that covers the entiretop surface of their body, but in females this plate coversonly about one-third of the front part of their body. Thisdifference in body structure allows females to swellgreatly by stretching the nonhardened portion of their$.50 G 7382 Printed on recycled paperMU GuideAGRICULTURALPUBLISHED BY MU EXTENSION, UNIVERSITY OF MISSOURI-COLUMBIA muextension.missouri.edu/xplor/Home and GardenTicksRichard M. HousemanDepartment of EntomologyFigure 1. Lone star tick. Female (A); Male (B), Mouthparts (C). Figure 2. American dog tick. Female (A); Male (B), Mouthparts (C). Figure 3. Brown dog tick. Female (A); Male (B), Mouthparts (C). Archivvrsion -- See extension.missouri.edubodies while they imbibe large amounts of blood duringfeeding. Males take small amounts of blood while feed-ing and do not become enlarged and swollen.Ticks and human diseaseTick bites may be irritating, but the possibility oftick-transmitted diseases causes greater concern.Rocky Mountain spotted feverRocky Mountain spotted fever is a rickettsial diseasecaused by Rickettsia rickettsii. Although a few cases ofthis disease do occur in the Rocky Mountains, most arereported in midwestern states such as Oklahoma,Missouri, and eastward to Virginia. Symptoms of RockyMountain spotted fever include a rash that often firstappears on the wrists and ankles. Later this rash spreadsto all parts of the body. The rash is usually accompaniedby headache, backache, high fever and general malaise.Signs may appear initially, or two days to two weeksafter an encounter with an infected tick. In a few cases,no rash occurs at all. Early diagnosis and antibiotic treat-ments are important. In Missouri, Rocky Mountain spot-ted fever is transmitted primarily by American dog ticksand lone star ticks. Prompt removal of ticks from theskin greatly reduces the chance of transmission forRocky Mountain spotted fever, because this pathogen isnot likely to be transferred during early stages of tickattachment.Lyme diseaseLyme disease is caused by the spirochete Borreliaburgdorferi. It probably is the most frequently reportedtick-borne disease in the United States. Since its discov-ery in the early 1970s near Old Lyme, Connecticut, it hasbeen reported widely throughout most of the country.The areas of greatest incidence in the United States arethe Northeast, the Atlantic seaboard, the Great Lakesstates, and northern California. Symptoms of Lymedisease may develop within 2–30 days following aninfective tick bite. These symptoms include fever,fatigue, headache, aching joints, nausea and a small redbump at the site of the bite. This bump may enlarge tobecome a spreading red ring called erythema migrans.Rashes and other dermal involvement are most easilyseen on light-colored skin. If you don’t see a rash, don’tassume there is no infection. Some people developpalpitations, dizziness and shortness of breath. Lymedisease may develop to the chronic stage with any of thefollowing symptoms: rheumatoid arthritis (primarily inthe joints of the arms and legs), facial paralysis, stiffneck, severe headache, and cardiac involvement.Infection and symptoms vary. Lyme disease in its earlyphases responds readily to antibiotics.Several hundred cases of Lyme disease have beenreported in Missouri. However, health authorities areunsure whether these cases are in fact Lyme disease ora condition with similar symptoms but caused by adifferent bacterium. In the northeastern and northcentral United States, the blacklegged tick, Ixodes scapu-laris (Figure 4), transmits Lyme disease. The species isfound in Missouri but rarely on humans. In the West,Lyme disease is transmitted by the western blackleggedtick, Ixodes pacificus. These unusually small ticks aremost likely to transmit the disease after feeding for morethan two days. Transmission of Lyme disease by theAmerican dog tick and the lone star tick has not yet beendemonstrated.Other diseasesOther human diseases that are associated with tickbites are tularemia and ehrlichiosis. Tularemia, knownmost commonly as rabbit fever, is caused by thebacterium Francisella tularensis. This bacterium is highlyinfective and infections generally follow the skinning ofrabbits or rodents, or the bite of a tick or horse fly.Symptoms resemble an influenza attack, with an initialhigh fever, a short remission and a further fever periodof two weeks. A lesion at the site of infection, conjunc-tivitis and enlarged lymph nodes may follow thesesymptoms.Ehrlichiosis is caused by several species of bacteriain the genus Ehrlichia. These rickettsia-like organismscause disease mostly in dogs, cattle, sheep, goats andhorses but may also infect humans. Several human caseshave been diagnosed in Missouri. The disease occursprimarily in the southeastern and south central regionsof the country and is transmitted primarily by the lonestar tick. Initial symptoms occur 5–10 days after the biteof an infected tick and generally include fever, headache,malaise and muscle aches. Other signs and symptomsmay include nausea, vomiting, diarrhea, cough, jointpains, confusion and occasionally rash. Rashes are morecommon in children than in adults.ControlFirst, avoid ticks if you can. Most ticks inhabitwoods and brushy areas with abundant wildlife thatserve as hosts. People walking through these areas areprone to tick infestations. If you go into these areas,examine your body thoroughly for ticks the next timeyou remove your clothing. Ask someone else to examineparts of your body that you can’t see.Page 2 G 7382Figure 4. Blacklegged tick. Female (A); Male (B), Mouthparts (C). Removing ticksPrompt removal of ticks will reduce the likelihoodof infection dramatically. Most disease transmissionoccurs after ticks have been attached for longer than24–36 hours. The proper way to remove a tick is to usea strong set of tweezers or forceps. Grasp the tick at thefront of the body and as close to the surface of the skinas possible, and slowly yet forcefully pull the tickstraight out from the body. Allow the natural elasticityof the skin to provide pressure to remove the tick. Do notgrasp or squeeze the rear portion of the tick’s body,either with your fingers or with forceps. This can expelthe gut contents of the tick into your tissues and increasethe likelihood of disease transmission if the tick isinfected with disease-causing organisms. This can alsocause the tick to break, leaving the mouthparts in theskin where a hard nodule (tick bite granuloma) willremain until your body naturally breaks it down. Smearing petroleum jelly on the tick, squirtinglighter fluid on it or holding a lighted cigarette or hotmatch up against it will not be effective at all. Whenfeeding, ticks are embedded so firmly that they can notvoluntarily release themselves from your tissues. Theonly time they can release is after they have fully fedthemselves. The only effective way to remove a tick isto pull it off as described above. After tick removal, usea local antiseptic at the site of the bite and dispose of thetick.Sometimes people wander into large numbers ofseed ticks. This can happen even on mowed lawnswhere a female tick has dropped from a passing animal.Literally thousands of these larvae can crawl up the legsof an adult or all over a child’s body. The best thing youcan do in these cases is to remove and launder infestedclothing and bathe with soapy, hot water to remove theseed ticks. If you notice the problem before seed tickshave attached, use a cotton ball soaked with rubbingalcohol to wipe them off.Tick repellentsIf you are in a tick-infested area, use tick repellents.The best available are aerosols containing a 0.5 percentpermethrin insecticide that can be applied to your cloth-ing. These products should only be sprayed on clothing,and the clothing must be dry before you wear it. Onceapplied, these products repel ticks and remain effectivethrough several launderings. You can purchase them ata sporting-goods or outdoors store. Products containingDEET may also be used. This repellent can be appliedto the skin and is found in several commercial productsfor mosquito and insect control, but it is only variablyeffective against ticks. Always read and follow the labelbefore applying insecticides to clothing or to your skin.LawnsChemical control in yards and recreational areas isusually not recommended. These areas are usually toolarge to make this treatment practical. Even when youtreat mowed lawns and areas around the lawn, outdoorchemical control is only marginally effective. If youdecide to try this anyway, treat tick-infested lawns anda band about 20 feet wide outside of the mowed areawith an insecticide labeled for tick control on yards  (ifthe label does not specify tick control in yards, it is notlegal to use it in that situation). Always follow label direc-tions, and do not allow children or pets access to the areauntil the spray has dried. You may need to hire a profes-sional pest management company for this work. Againgeneral treatment of yards is not usually recommended.You may treat homes infested with brown dog ticksby applying insecticide to cracks and crevices where yousee ticks. This may require the services of a professionalpest management company.PetsTick control on animals is also important. Many petowners choose simply to remove ticks regularly fromtheir animals by hand. Other pet owners use chemicalproducts to treat their pets for ticks. Dust or shampootreatments that contain pesticides are often used, butremember that repeated applications are needed whenusing these products. Tick collars are another option.These collars contain pesticides that kill ticks around thehead and neck of pets. Manual inspection and removalof ticks on other areas of the body may still be necessarywhen using tick collars. In addition, collars need to bereplaced occasionally in order to remain effective. Whenusing tick collars, read the package carefully for instruc-tions on use. Do not attempt to use these products forcontrolling ticks on humans.Your local veterinarian can prescribe certain pesti-cides for tick control on animals. These products arespot-on, which means you apply a few drops betweenthe shoulder blades of your pet. The chemicals movethrough the oils of the skin to provide protection on allareas of the body. These products typically persist for upto a month. They are not repellents, so ticks may stilltemporarily attach to the animal, but those that attachtypically die within 24–48 hours.G 7382 Page 3Page 4 G 7382 Revised 5/02/7M Issued in furtherance of Cooperative Extension Work Acts of May 8 and June 30, 1914, in cooperation with the United States Department ofAgriculture. Ronald J. Turner, Director, Cooperative Extension, University of Missouri and Lincoln University, Columbia, MO 65211. UniversityOutreach and Extension does not discriminate on the basis of race, color, national origin, sex, religion, age, disability or status as a Vietnamera veteran in employment or programs.  If you have special needs as addressed by the Americans with Disabilities Act and need this publicationin an alternative format, write ADA Officer, Extension and Agricultural Information, 1-98 Agriculture Building, Columbia, MO 65211, or call(573) 882-7216. Reasonable efforts will be made to accommodate your special needs.OUTREACH & EXTENSIONUNIVERSITY OF MISSOURICOLUMBIAWarning on the use of chemicalsApply chemicals only where needed or justified. Beforeusing any chemical, please read the label carefully fordirections on application procedures, appropriate rate,first aid, storage, and disposal. Make sure that the chem-ical is properly registered for use on the intended pestand follow all other label directions. Keep insecticides inoriginal containers, complete with labels, and keep themout of the reach of children and pets. Do not allow chil-dren or pets near treated areas before these areas dry.Carefully and properly dispose of unused portions ofdiluted sprays and empty insecticide containers.

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