4. Ticks
1)
Characteristics:
a) Body parts:
i) _______________________
ii) _______________________
b) _____________________________
c) Legs:
i) Larval: ___
ii) Nymph:____
iii) Adults:______
iv) Haller’s organ: Sensory pore located on Tarsus of forelegs
d) Hypostome: ______________________________
1
2)
Families:
a) Argasidae: _____________________
b) Ixodidae: _________________________
2
Morphology
1) Capitulum (head) composed of:
a) ____________________________
b) ___________________________
c) _____________________________
d) ______________________________
2) Basis capituli: ___________________________________
3) Hypostome:
a) _______________________________
b) _________________________________________
c) _____________________________________
4) Chelicerae:
a) ________________________________________
b) ______________________________
c) _______________________________
5) Palps:
a) ______________________________________
b) _____________________________________
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6) Feeding:
a) Chelicerae pierce the host’s skin
b) The barbed hypostome is thrust deeply into wound
c) Salivary glands produce a secretion that prevents blood clotting
d) Blood is pumped in by the pharynx and forced backward into the
esophagus and midgut
e) Diverticulum, attached to the midgut, becomes greatly distended to store a
large quantity of blood
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Tick Transmitted Diseases
1) Ticks are among the most efficient vectors of disease.
Table 1: Ticks commonly found on dogs and cats
Tick
Common
Name
Geographic
Distribution in U.S.
Tick-associated Disease(s)
in Dogs and Cats*
Amblyomma
americanum
Lone star tick
Southeast, Midsouth and
coastal Northeast
Ehrlichiosis, tularemia, Rocky Mountain
spotted fever, tick paralysis
Anblyomma
maculatum
Gulf Coast tick
Gulf Coast to Midsouth and
lower Midwest
Hepatozoonosis
Dermacentor
variabilis
American dog
tick
Eastern 2/3 of U.S.; West
Coast
Ehrlichiosis, tularemia, Rocky Mountain
spotted fever, cytauxzoonosis, tick
paralysis
Dermacentor
andersoni
Rocky Mountain
wood tick
Northwest; Northern Rocky
Mountain states
Rocky Mountain spotted fever, tularemia,
cytauxzoonosis, tick paralysis
Ixodes
scapularis
Eastern blacklegged tick (deer
tick)
States east of and adjacent
to Mississippi River; Eastern
TX and OK
Lyme disease, anaplasmosis, tick
paralysis
Ixodes pacificus
Western blacklegged tick
West Coast and Eastern NV
Lyme disease, anaplasmosis
Rhipicephalus
sanguineus
Brown dog tick
Throughout U.S
Ehrlichiosis, Rocky Mountain spotted
fever, babesiosis, anaplasmosis,
hepatozoonosis, haemobartonellosis
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Tick Bite Paralysis
1) ________________________________________
2) ______________________________________________________________
______________________________________________________
3) Symptoms:
a) 6-7 d after attachment; while engorgement is occurring
b) ___________________________________________________________
________________________________________________________
c) ___________________________________________________________
4) Humans:
a) Most often occurring in children under 7 (rare in grown persons)
b) Rather high fatality rate (U.S.; 1950- 94 cases, 12 deaths)
c) Occurs most commonly in northwest & southeastern regions
d) Typical site of bite: __________________________________
e) Treatment:
i)
__________________________________
ii)
_____________________________________________
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Lyme Disease
1) AKA:
a) Lyme borreliosis
b) Borreliosis
2) Symptoms:
a) EM:
i)
Erythema chromium migrans
ii)
_______________________________________________
iii)
May become over 12” and becomes clear in the center (bull’seye)
iv)
Typically not painful
b) _______________________________________________________
3) Causal agent: _______________________________________________
4) Vectors:
a) Eastern U.S.: Deer tick (black-legged tick),
b) Northwest U.S.: black-legged tick, Ixodes pacificus
c) Texas: Probably ______________________________________
5) History:
a) _______________________________________________________
b) Associated with a cluster of childhood arthritis cases in that county
c) Cases:
i)
100,000 cases since 1975 in 44 states
ii)
Most commonly reported vector borne disease in the U.S.
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6) Disease cycle:
a) For disease to occur in an area, three elements must be present:
i)
_________________________________________
ii)
_______________________________________
iii)
____________________________________________
b) Adults:
i)
_______________________________________
ii)
Mate in the fall & winter
iii)
Eggs laid in spring & summer
c) Larvae:
i)
Feed once (several days) on small rodents, birds and man
ii)
_____________________________________________
iii)
Molt in the fall or spring to nymphs
d) Nymphs:
i)
About the size of a pin-head
ii)
___________________________________________________
e) Disease transmission:
i)
Biological transmission
ii)
_____________________________________________________
iii)
_____________________________________________________
_____________________________________________________
iv)
Surface structure of the bacteria changes as it passes and
increases in number
7) Vaccine (CDC):
a) LYMErix
b) Kills pathogen within the gut of the feeding tick
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Rocky Mountain Spotted Fever
1) Casual agent:
a) _________________________________________________
b) The most severe tick-borne disease in the U.S.
2) Name: _____________________________________________________
3) Distribution: All states except Hawaii, Alaska
4) Vectors:
a) Western U.S.: Rocky mountain wood tick, Dermencentor andersoni
b) Eastern U.S.: American dog tick, D. variablis
c) Texas: Lone star tick, Amblyomma americanum
d) Pacific coast: Pacific coast tick, D. occidentalis
5) Reservoirs:
a) Reservoir ticks: Transovarial & transadial transmission
b) Reservoir hosts: Rodents
6) Disease cycle:
a) __________________________________________________
b) ___________________________________________________
c) Rodent populations play an important role in maintaining the disease in an
area
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Tularemia (Rabbit fever)
1) Pathogen:
a) ___________________________________________
b) ________________________________ (formerly Pasteurella tularensis)
2) Hosts:
a) Wide variety of hosts
b) _________________________________________________
3) Vectors:
a) Ticks:
i)
Dermacenter spp.
(1) Rocky mountain wood tick
(2) American dog tick
ii)
Amblyomma spp. (Lone star tick)
iii)
Haemaphysalis spp
.
b) Transmission:
i)
Ticks:
(1) Transovarial
(2) Transstadial
ii)
Humans:
(1) _____________________________________
(2) _____________________________________________
(3) ____________________________________________
(4) ______________________________________________
4) Distribution: Continental U.S.
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Hard Ticks
1) Family __________________________
2) Characteristics:
a) _______________________________________
i)
_________________________________________
ii)
Male- large; visible when feeding
b) Capitulum extends forward from anterior end of cephlothorax
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3) Development (Four stages):
a) Egg
b) Active stages:
i)
Larvae: 6-legged
ii)
Nymph:
(1) 8-legged
(2) One instar
iii)
Adult: 8-legged
4) Feeding:
a) All stages are blood feeders
b) Generally one blood meal between each active stage
c) Only females become distended when feeding
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5) Hosts:
a) One-host ticks: Virtually entire life cycle passed on one host
b) Two-host ticks:
i)
Larva attached to one host
ii)
Molts to the nymphal stage leaves that host
iii)
Molts to adult stage find second host
c) Three-host ticks: Requires three hosts to complete its life cycle
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6) Genera:
a) Amblyomma
b) Boophlius
c) Dermacentor
d) Haemaphysalis
e) Ixodes
f) Rhipicephalus
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Genus: Amblyomma
1)
Characteristics:
a) Most species have whitish markings
b) Long palpi
c) Long hypostome
d) Festoons on posterior margin of the abdomen
e) Anal groove below anus
2)
Species:
a) World - 90; U.S. - 8
b) More common in the tropics
c) U.S.: East of central Texas to the Atlantic coast and north to Iowa
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Amblyomma americanum
Lone star tick; Speckback tick
1) Characteristics:
a) Females: Solitary white or gold colored spot on posterior scutum
margin
b) Males:
i)
Smaller than females
ii)
Several scattered whitish spots on scutum
c) Larvae: No distinctive marks
2) Distribution: West Texas north to Missouri east to the Atlantic coast
3) Hosts:
a) Three host ticks:
i)
Each stage detaches from host after obtaining a blood meal
ii)
Molts to the next stage
iii)
Adult female drop to ground and deposit eggs, then dies
b) Larvae and nymphs: Generally on smaller wild animals and ground
inhabiting birds
c) Adults: Larger wild and domestic animals including man
d) Feeding location:
i)
Axillaries
ii)
Udders
iii)
Scrotum
iv)
Neck
v)
Tailhead
vi)
Escutcheon
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e) Common hosts:
i)
Man
ii)
Livestock
iii)
Dogs
iv)
Deer
v)
Birds
4) Biology:
a) Life cycle:
i)
Larvae engorge for 3 - 9 d fall to the ground and molt in 12 - 30 d
later into nymphs.
ii)
Nymphs engorge for 3-8 d fall to the ground and molt in 13-46d
iii)
Females:
(1) Engorge for 11-24 d
(2) Mate and drop off
(3) Oviposition 5-13 d (~ 3,000-4,000 eggs over ~21 d)
iv)
Egg hatch ~ 30 d
b) Habitat: Communities that provide support for wildlife and offer an
optimum microenviroment for engorge tick to oviposit or molt
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5) Parasitism:
a) The elongated mouthparts create deep, irritating wounds
b) Heavily infested animals suffer severely from the bite and may develop an
anemic condition due to blood loss
c) May cause tick paralysis in man and dogs
6) Diseases transmitted:
a) Spotted fever
b) Ehrlichiosis
c) Possibly:
i)
Lyme disease
ii)
Q fever
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Amblyomma maculatum
Gulf coast tick
1) Characteristics:
a) Numerous diffuse pale markings
b) Possesses spurs on second, third and fourth pairs of legs
c) More elongate than the lone star tick
2) Distribution:
a) Areas with high temperatures and humidity
b) Within 100 miles along the Gulf coast and south Atlantic coast
c) Have been found as far inland as Oklahoma
3) Hosts: Three host tick
a) Adults:
i)
Livestock (cattle, goats, sheep, horses)
ii)
Deer
iii)
Dogs, coyotes, wolves
iv)
Man
b) Larvae & nymphs:
i)
Ground foraging birds (meadowlarks, quail & others)
ii)
Small wild animals
c) Host location:
i)
Birds: Head and neck
ii)
Animals: Head; particularly the ears
19
4) Biology:
a) All stages are susceptible to desiccation
b) Larvae:
i)
Engorge for 3.5 – 7 d detach and fall off
ii)
Molt into nymph 9-12 d
c) Nymph:
i)
Attach about the head and neck
ii)
Feed for 4.5 - 7 d
iii)
Molt into adults in 19-28 d
iv)
Prevalent during late winter and spring
d) Adults:
i)
Prevalent during spring but most remain inactive until summer
ii)
Females do not engorge until fertilized
iii)
After engorgement (14-18 d) females drop to the ground and seeks
a secluded place to oviposit
iv)
Previpositon period: 2-5 d
v)
Excavates secluded hole; lays 8,000 to 9,000 eggs (13-75 d)
e) Males:
i)
Generally seek host prior to the arrival of females
ii)
Remain on host several weeks after females complete feeding
5) Parasitism:
a) Elongated mouthparts produce deep, irritating wounds which cause the
animals to rub their ears
b) Severely damaged ears may curl inward resulting in “gotched ear”
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Genus: Dermacentor
1) Characteristics:
a) Ornate; pale markings on the scutum
b) Festoons present (11)
c) Basis capituli quadrangular dorsally
d) Palps wider than long
e) Anal goove below anus
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Dermacentor variablis
American dog tick
1) Characteristics:
a) Pale whitish or yellowish markings on scutum
b) Engorged female specimen are slate gray
2) Distribution: East of the Rocky Mountains, Pacific coast, Idaho, Washington.
3) Hosts:
a) Preferred host- dogs
b) Large mammals including man
c) Larvae and nymphs prefer smaller animals (rodents)
4) Biology:
a) More common near roads and trails
b) Adults commonly found in the spring in their “waiting position” on grass
and other low vegetation
c) The third pair of legs is used to cling to the grass while the other legs are
waved about ready to grasp any host that comes by
d) The male remains on the host indefinite alternating feeding and mating
e) Female feeds, mates, engorges, drops off to lay thousands of eggs
f) Attracted by the scent of animals
5) Parasitism: Often encountered by persons frequently outdoors
6) Disease transmission:
a) Rocky mountain spotted fever
b) Canine babesiosis
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D. albipictus
Winter tick
1) Characteristics:
a) Extensive white markings, white streaked with brown
b) Mouthparts short and blocky
2) Distribution:
a) Widely distributed
b) Occurs frequently in wooded areas
3) Hosts- Large animals:
a) Domestic:
i)
Horses
ii)
Cattle
b) Wild:
i)
Deer
ii)
Antelope
iii)
Moose
4) Biology:
a) One host tick
b) Usually found on animals during the winter
5) Parasitism: Heavy infestations can cause edematous condition called “water
belly”.
6) Disease vector: Probably bovine anaplasmosis
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Genus: Haemaphysalis
1) Characteristics:
a) Anal groove below anus
b) Palps wider than long
c) Festoons present
d) Basis capituli rectangular
Haemaphysalis leporispalustris
Rabbit tick
1) Characteristics:
a) Small
b) Inornate
c) No eyes
d) Festoons present
e) Second segment of the palpus produced laterally (angular projections)
2) Distribution: Entire continental U.S.
3) Hosts: 3-host tick
a) Rabbits and other small mammals (rodents, dogs, cats etc)
b) Man
4) Biology:
a) All stages active throughout the year in warmer climates
b) Female:
i)
Engorgement ~17 d
ii)
Drops off during the day when the host is resting
iii)
59-2400 eggs deposited
c) Eggs hatch in after at least 22 d
d) Larvae engorge for 4-10 days then detach; molting- 18-134 d
e) Nymphs attach and engorge for 4-8 d; molting- 13-124 d
5) Parasitism: Adults attach to the ears, around eyes and about the head
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Genus: Rhipicelphalus
1) Characteristics:
a) Anal groove below anus
b) Palps wider than long
c) Festoons present
d) Basis capituli hexagonal
Rhipicelphalus sanguineus
Brown dog tick
1) Distribution: World wide
3) Hosts:
a) Primarily dogs; frequently in ears and between toes; other small mammals
b) Rarely man
4) Biology: Three host tick
a) Oviposition begins three days after female drops off host.
b) Female lays 4,000-5,000 eggs in a 21-29 d period
c) Eggs laid under stones, in crevices, in walls; hatch in ~19d
d) Larvae congregate near bottom of walls waiting for a suitable host
e) Once attached, larvae engorge in ~3 days, detach and molting in at least
6d
f) Nymphs engorge for 4 days; molting occurs in 12 days
g) Life cycle ~ 63 d (favorable conditions); Several generations/ yr
5) Diseases transmitted:
a) Canine ehrlichiosis (malignant canine rickettsiosis)
b) Salmonella enteritidis, causes a parathyroid disease of dogs
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Genus: Ixodes
1) Characteristics:
a) Anal groove above anus
b) Palps longer than wide
c) NO festoons
d) Basis capituli rectangular
Ixodes scapularis
Deer tick, black-legged tick
1) Distribution: Eastern U.S.
3) Hosts: 2 or three host tick
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Genus: Boophilus
1) Characteristics:
a) Short palpi with a ridge dorsally and laterally on each segment
b) Hexagonal basis capituli
c) Posterior margin of the abdomen is without festoons
d) Anal groove below anus
2) Biology: One host ticks
B. annulatus
Texas fever tick, Cattle fever tick, Cattle tick
1) Prior to 1943 consider the most important livestock tick
2) Eradicated in 1943 and currently only sporadic sightings (12-18 times
per year) occur in the southern U.S. as a result of quarantines
3) Disease vectored:
a) Cattle tick fever, babesiosis (Babesia bigemia)
b) Anaplasmosis
B. microplus
Southern cattle tick
1) Similar in appearance, life cycle and habits to the cattle tick.
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Soft Ticks
1) Family: Argasidae
2) Characteristics:
a) Do not possess a scutum (dorsal shield)
b) Capitulum located on ventral side and not visible from above
3) Development:
a) Egg
b) Active stages:
i)
Larvae (6-legged)
ii)
Nymph
(1) 8-legged
(2) Several nymphal instars
iii)
Adult (8-legged)
4) Feeding:
a) All stages are blood feeders
b) Multiple feeders in the adult stage
5) Biology: Female may deposit several small batches between blood meal
6) Genera:
a) Argas
b) Otobius
c) Ornithodoros
28
29
Argas spp.
Fowl ticks; blue bugs
1) Three closely related species:
a) Argas persicus; northeastern U. S.
b) Argas radiatus; southeast and southwest
c) Argas sanchezi; southeast and southwest
2) Identification:
a) Oval
b) Body flattened with a suture line dividing dorsal and ventral sides
c) Leathery body covering
d) Color: red; blue-black; gray
3) Hosts:
a) Domestic fowl (especially chickens)
b) Attached under wings and areas where feathers are sparse
4) Biology:
a) Spend most time off host; in cracks and crevices of poultry house
b) Nocturnal feeders
c) Female lay 25-245 eggs in seven or more batches
d) Eggs hatch in 8-21 d
e) Larva feed for 2-10 d; molts in 4-16 d
f) Nymph
i)
Two (sometimes 3) instars
ii)
Require 7-28 d to molt to next stage
30
5) Parasitism:
a) Chickens are often unthrifty
b) Ragged plumage
c) Diarrhea
d) Decreased egg production
6) Diseases vectored:
a) Fowl spirochetosis
b) Fowl paralysis
c)
Fowl piroplasmosis
31
Otobius megnini
Spinose Ear tick
1) Characteristics:
a) Nymphs:
i)
Body spinose
ii)
Mouthparts are long and slender
b) Adults:
i)
Body granular
ii)
Devoid of spines
iii)
Hypostome without teeth (non-functional)
2) Hosts (commonly found in the ear):
a) Cattle (most common; only soft tick attacking cattle)
b) Horses and mules
c) Sheep, goats
d) Dogs and cats
e) Man
f) Wild animals (coyotes, deer cottontail and jack rabbits)
g) Prevalent in arid and semiarid regions; S. and SW Texas
3) Biology:
a) Adults do not feed
b) Females
i)
Mate once, oviposit 350-1600 eggs over a 6 month period
ii)
Eggs hatch in 10-23 d
c) Larvae: Crawl up weeds and wait for host then enters ear and seek folds
to begin feeding; molts in ear
d) Nymph:
i)
Remain in ear
ii)
Two instars
32
Ornithodoros species
1) Identification:
a) Globular body
b) No suture line between dorsal and ventral surfaces
c) Body roughened or warty appearing with tiny protuberances
d) Hypostome with well developed teeth
2) Hosts:
a) Cattle
b) Deer
3) Biology:
a) Nest ticks; secret themselves in animal bedding
b) Do not attach themselves to a moving host
c) Wait for host to recline
4) Diseases vectored:
a) Relapsing fever
b) Epizootic bovine abortion (Borrelia coriaceae; spirochete)
33
Tick Control
Surveys
1) Valuable in determining:
a) Tick species present
b) Ticks infected
c) Need for control
d) Results of control efforts
2) Methodology:
a) Hand picking from animals
b) Tick drags:
i)
White flannel cloth ~1 X 1.5 yards attached to a yard long stick
ii)
Attached to a cord
iii)
Drag over brush and low vegetation beside roads and paths
c) Carbon dioxide method:
i)
Ticks respond to CO2 breathed from animals
ii)
Place ~ 2 LBs of dry ice (frozen carbon dioxide) on a wire-mesh
screen in the center of a 3 feet square piece of white cloth
iii)
Place near roads or paths
34
Humans
1) Keep clothing buttoned
2) Tuck pants legs in tops of socks
3) Avoid sitting on ground
4) Inspect clothing and body regularly
5) Tick repellents: DEET is the best
Livestock
1) Control generally directed against infested host on which the ticks feed.
2) The goal is to prevent the engorgement of females
3) Methods and treatment techniques will vary depending on:
a) Whether the tick is a 1, 2, or 3-host tick.
b) One host ticks spend more time on the host
c) Attachment site (ear or body tick etc.)
4) Control methods:
a) Insecticide impregnated ear tags
b) Insecticide impregnated rubs
c) Ivermectin
d) Drench
e) Habitat modification
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