A non-sensational look at ticks

Ticks

Winter tick Lyme disease

Ixodidae Argasidae Hard Ticks Soft ticks Hard dorsal plate over abdomen (♀ anterior half, ♂ entire E, L, N, Adult 1, 2, or 3 (90%) hosts, mostly mammals ♀ 1 very large blood meal, 5,000+ eggs in 1 mass – 1 / 2yr life cycle Seasonal activity pattern Leathery folded cuticle 2+ nymphal stages Multi-host life cycle, >3, mostly bats or birds ♀repeated small blood meals, several batches ~ 500 eggs, live many yrs No seasonal pattern

Ixodidae – hard ticks Prostriata Ixodes largest genus Blacklegged tick Metastriata Amblyomma Lone star tick Dermacentor American dog tick

Argidae – soft ticks Feed on birds or bats Dry environments - caves

Tick feeding Obligate ectoparasites - all ticks feed on blood during some or all life stages Seek, feed, drop, molt Generally long-lived Can survive 1 yr or more without feeding

Tick feeding Contact Host acceptance – recognition features Cut skin w/ cheliceral digits Insert hypostome Produce cement (ixodids) – Salivate – Feed Detach Drop

Tick feeding Anticoagulants Antihemostatic compounds - vasodialators Can block host response – itching, etc. Hard ticks (ixodids) feed gradually (2d larva, 13 d ♀- creates new cuticle to expand abdomen Soft ticks (argasids) small meals – 35 to 70 min

Ixodid life cycles 1, 2, 3 hosts 90% of ixodids

Host Recognition > 85% ixodix and argasid – relatively strict host specificity Odors – CO 2, “animal breath”, ammonia and other waste odors, butyric acid, lactic acid Radiant heat – small increases in T can be synergistic w/odors Visual images – for certain hunter ticks Vibrations – vegetation – questing height

Nidicolus ticks Live near nests of hosts – uniform temperature and humidity Behavior that restricts distribution – avoid bright sunlight, low humidity Active when hosts are present May wait long periods for host return

Diapause Survival during adverse time (cold, heat, excess moisture, drought Inactive - reduce metabolic rate, do not feed Newly molted larvae, nymphs, adults during declining photoperiod – host seeking diapause Morphogenic diapause delayed development or oviposition

Host Recognition 85% ixodix and argasid – relatively strict host specificity Many nidicolous ticks (nidus = nest) Only bats, only large ruminants Opportunistic feeders - wide host range Blacklegged tick – 120 hosts I. ricinus – 300 species

Water balance Retreat to shelter if becoming desiccated, leaf litter, thatch Hygroscopic salivary secretion – collect atmospheric water on mouthparts Desiccation tolerance can limit distribution Shade, increased humidity, host food plant

Drop-off timing Non-nidicolous ticks Associated with host behavior Disperse fed ticks in optimum habitats Photoperiod appears to be dominant factor When hosts are inactive – after nightfall During daylight for nocturnal hosts

Ticks and Diseases

Why are ticks good vectors? Obligate blood feeding – several hosts Long lived High reproductive potential Few natural enemies Sclertoized bodies – protected from environmental stress Slow feeding – acquisition and dispersal

Why are ticks good vectors? Transstadial passage of pathogen Transovarial passage Substances in saliva Large blood meal More gradual change during development compared to insects -

Blacklegged tick Ixodes scapularis (I. damni)

Blacklegged tick Pest of people and domestic animals in eastern & south-central, & midwest US Major vector of Lyme disease Borrelia burgdorfi L & N – late winter and early spring – feed on small mammals, lizards, birds A – fall & early spring white-tailed deer All stages will bite humans

Lyme Disease Most commonly reported vector-borne disease in US, Europe, temperate regions of northern hemisphere Reported as form of inflammatory arthritis mid-1970’s New Lyme, CT Causal agent found in At least 3 spp Borrelia spirochete

Lyme Disease Erythema migrans – creeping rash (60 – 80% patients, fever, headache Diagnosed from rash and tick exposure Can spread to joints, heart, nervous system Can be successfully treated with antibiotics No vaccine available

Lyme Disease NY focus area 30% N, 50% A infected 36 hrs of attachment needed Live near forests Reservoirs – maintain spirochetes for long time, frequent contact w/ticks, readily infect ticks White-footed mouse, eastern chipmunk, shrews White-tailed deer not reservoirs but sustain and disperse ticks

Why nymphs? Nymphal stage is mostly likely to transmit Lyme disease spirochetes to humans –Larger numbers compared to adults –Small size, easier to overlook –Abundant in summer when people are more active outdoors

Chronic Lyme effects - variable Cardiac stress Arthritis – joint pain, particularly knees Neurological problems – inflammation of brain, temporary paralysis, memory loss

Lone star tick Amblyomma americanum

Lone star tick L, N, & A will attack most any mammal & ground-feeding bird Often abundant with large deer populations N & A emerge from winter diapause in spring STARI, human erlichiosis

Lone star seed ticks

Tick Bite Allergies Localized inflammation Bites of soft ticks can cause severe systemic reactions – skin rash, nausea, vomiting, shock

Wildlife impacts

Southern Tick- Associated Rash Illness (STARI) 1 – bite 2 – edge of rash 3 – cleared area

Southern Tick- Associated Rash Illness (STARI) Similar to Lyme disease Rash, fatigue, headache, muscle & joint pain following bite of lone star tick “Bulls-eye” rash about 7 days after bite No chronic effects – joints, heart, nervous system Clears following use of oral antibiotics

American dog tick Dermacentor variabilis Pest of people and domestic animals in eastern & south- central, & midwest US L & N – late winter and early spring – feed on small mammals A – medium-sized mammals & humans – late spring & early summer Must be attached > 10h Rickettsia becomes virulent only after long tick attachment 1 – 3% tick infection rate Dog ownership is risk factor with RMSF No vaccine available Antibiotic treatment within 5 d

Rocky Mountain Spotted Fever Rickettsia intracellular bacterium Disease of circulatory system – multiply in blood vessels Fever, headache, joint pain Tiny pink or reddish spots Mortality rate 2 – 5%

Rocky Mountain Spotted Fever 50% of cases in south Atlantic states 2/3 cases children < 15 years old American dog tick, common in KY Transstadial transmission Transovarian transmission

Pathogen surveillance Direct or indirect fluorescent antibody techniques Serological surveys Hospital records

Vector management Reduce immigration – ticks have limited movement but hosts can carry them long distances –Habitat & food management Increase mortality – pesticide applications Reduce reproduction – bait stations for hosts

Tick surveillance techniques Drag cloths – questing individuals over specific distance CO 2 -baited traps – requires mobile ticks Host collections – live trapping, anesthetize, ID immature stages

Tick surveillance techniques

Caged sentinel hosts Aspiration of nests Artificial nest box traps From collector’s clothing

Ticks and the FEI World Equestrian Games The American dog tick – a known vector of equine piroplasmosis (EP) EP is not endemic in the US but epidemics were reported in Florida in 1961 and 1965 A tick management program must be implemented as part of the animal health effort for 2010.

Numbers 1400 acres+ 770 trapping days 94 miles of fence lines and field areas 5 ticks

Ky Horse Park Ticks American dog tick – field mice and raccoon Groundhog tick – possum, raccoon, striped skunk

Groundhog tick or carnivore tick Ixodes cookei Rarely quests on vegetation, lives in burrow of host Very low human contact

Squirrel tick I. marxi

Ky Ticks – Wildlife host study Dermacentor albipictus winter deer tick 1- host tick, eastern KY – deer, elk Amblyomma maculatum – Gulf Coast tick, 3-host tick, L & N small rodents and ground dwelling birds, A – ears of large mammals Ixodes scapluaris – blacklegged tick 3- host tick wide range of mammals and birds

Pesticide-treated cotton balls Mouse takes to den Ticks on mice are killed