A non-sensational look at ticks. Ticks Winter tick Lyme disease

A non-sensationallook at ticks

Ticks

• Winter tick http://www.youtube.com/watch?v=Rsd2i-qFHK4

• Lyme disease• http://www.youtube.com/watch?v=O72bnVlsQR4&feature=related

Ixodidae ArgasidaeHard 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 – CO2, “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 ticksLive 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 tickIxodes 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 1981 -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 tickAmblyomma 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

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 – bite2 – edge of rash3 – 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 tickDermacentor 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%

1994 - 98

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

1994 - 98

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

• CO2-baited traps – requires mobile ticks

• Host collections – live trapping, anesthetize, ID immature stages

Tick surveillance techniques

Tick surveillance techniques

• Caged sentinel hosts

• Aspiration of nests

• Artificial nest box traps

• From collector’s clothing

Ticks and theFEI 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.

Numbers1400 acres+

770 trapping days94 miles of fence lines

and field areas5 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