Parasitology Ticks Flashcards
Phylum, class, families of ticks
Phylum Arthropoda
Class Arachnida
Family Argasidae- soft ticks
Family Ixodidae- hard ticks
Why are ticks important?
Are vectors of many disease- bacterial, viral, rickettsial, fungal, and protozoal
Can cause disease directly
Cost billions of dollars a year to control and to treat tick transmitted diseases
Why are ticks good vectors?
most are persistent blood feeders, feed slowly
highly scerlotized
have few natural enemies
have wide host range
long lived, with high reproductive potential
Transmission of pathogens is transovarian, transstadial, and/or intrastadial
Transovarian transmission
female can transmit disease to eggs
larvae come out infected
(not in lyme disease transmission)
Transstadial transmission
stage-to-stage
Diseases and disorders caused directly by ticks
dermatoses
feeding introduces biologically active substances or toxins
can cause: exsanguination, tick paralysis, otoacarisis (ear infection caused by soft tick)
Basic identification of hard ticks
Body composed of capitulum and idiosoma (with scutum)
Capitulum is composed of mouth parts plus basis capituli
Parts of the capitulum
Basis capituli (aka base of capitulum) Mouth parts: palps, chelicerae, hypostome
Purpose of chelicerae
cuts and slices
Purpose of hypostome
anchors tick
also with cementing substace
Structure of hard ticks
teardrop shaped capitulum visible festoons, ornate (+/-) scutum sexual dimorphism
Anal groove will be
anterior
posterior
or absent
Structure of soft ticks
body oval, leathery
capitum not visible, no scutum
no festoons
no sexual dimorphism
Prostriate tick mating
mate while still in the environment
males may mate again while on host
usually more females on host than males
Ex. Ixodes
Metastriate tick mating
males require a blood meal before they become sexually mature
sexual maturity doesn’t complete until male and females have fed
usually more males than females on host b/c females fall off and males seek out new females to mate with on host
Ex. Rhipicephalus, Dermacentor, Ambylyomma
What are the 3 types of host finding
questing
nidicolous
non-nidicolous
Nidicolous host finding
live in host den or nest (soft ticks)
Non-nidicolous host finding
found along paths, trails, etc. where hosts are likely to pass
Tick feeding
pool feeders; excrete substances that effect hemostasis and immune response
concentrate blood meal-water back into host (toxins, pathogens)
intracellular digestion- blood stays in gut long periods- helps protect pathogens
most ticks require several days to complete feeding- if don’t feed long enough no transmission occurs (except H. americanum by A. maculatum)
Important pathogens have adapted to survive in the tick
Pathogen transmission
Different pathogens require different times to be re-activated or undergo development in the tick, may also have to migrate to the mouth parts to be transmitted
Immunity of the host may increase transmission time
Different pathogens may take different times to be transmitted by the same tick species
Different genera of ticks may take different times to transmit the same pathogen
Otobius megnini
soft tick
spinose ear tick
cattle and dogs
Hot, drier range areas, rocky habitats, shelter or barn
Nymphs in ear, adults are free living and breed off of host
Ixodes scapularis, basics
black-legged deer tick
3 host tick
life cycle can take up to 2 years
anal groove is anterior; genital opening is missing in nymphs
Disease transmission of Ixodes scapularis/pacificus
Lyme disease spirochete (Borrelia burgdorferi)
Babesia in humans
Anaplasma phagocytophilium
Feeding habits of Ixodes scapularis larvae and nymphs
small mammals and birds
this is where they pick up lyme disease
Feeding habits of Ixodes scapularis adults
deer and other larger mammals (dogs)
have to be attached for 2 days to transmit lyme disease
Amblyoma americanum, general info
lone star tick, 3 stage host
Larvae and nymphs feed on birds and small mammals
Adults feed on large mammals
Diseases transmitted by Amblyoma americanum
Minor role with RMSF
Ehrlichiosis chaffeensis- human monocytic ehrliciosis
E. ewingi- canine and human granulocyticehrliciosis
STARI (southern tick associated rash illness; B. lonestari- closely related to lyme disease)
Amblyomma maculatum
Gulf Coast tick of cows and dogs
Transmits Hepatozoon americanum (not the same as hepatozoonosis in other parts of the world), often fatal and difficult to treat
Is a 3 host tick
Dermacentor variabilis
American dog tick, very common
3 host tick
larvae and nymphs feed on mice and small mammals
adults feed on large animals including dogs, cattle, humans
life cycle 1 or 2 years
What does Dermacentor variabilis transmit?
RMSF (Rocky Mountain Spotted Fever)
Cytoxzoan felis to cats
E. canis to dogs
Rhipicephalus sanguineus, general
brown dog tick
3 host tick, but dog is preferred for all stages
will reproduce in home and kennel environments
can complete life cycle in 2 months
What diseases are transmitted by Rhipicepalus sanguineus
Ehrlichia canis
possibly A. platys
Babesia canis and Babesia gibsoni
Hepatozan canis (dogs
Brief details of appearance of Rhipicephalus sanguineus
Basis capituli has lateral expansion
Is not ornated
Festoons
Rhipeecephalus (Boophilus) annulatus
Texas cattle fever tick
1 host tick
eradicated from US but still in Mexico
Reportable tick
Tick paralysis
Ascending motor paralysis
Toxic stuff in salica
Tick(s) usally found on neck or near head (can be caused by one, but often several are present)
Removal of tick is the treatment
All spp can cause it but in US is usually Dermacentor variabilis, Dermacentor andersoni, Amblyomma americanum, and Ambylomma maculatum
Tick control
chemical toxicants (drugs)
biological control
habitat modification
host manipulation
Lyme disease control
vaccination
doxycycline has been used in humans if tick has been found, not proven in dogs
Removing a tick
Do not squeeze it
Use blunt forceps
Grasp the basis capituli and apply steady constant pressure
