Ticks

Question 1

What are these structures?

Answer 1

Things on either side are palps, middle thing is a hypostome

Question 2

What are the ticks established in Western Canada?

Answer 2

• Dermacentor variabilis (AB, SK, MB)
• D. andersoni (BC, AB, ~SK)
• D. albipictus (all)
• Ixodes scapularis (Southern MB)
• I. pacificus (BC)
• wildlife ticks are occasionally found on pets: Ixodes kingi, Ixodes cookei, Haemaphysalis leporispalustris (rabbit tick usually found on Fe)

Question 3

Pathogenesis of tick infestation?

Answer 3

• All ticks: anemia; dermatitis, alopecia; local bacterial infection of bites
• some ticks: paralysis: salivary toxin of female tick; alpha-gal syndrome (red meat allergy); pathogen transmission

Question 4

What are the 3 main questions to ask when ID’ing ticks?

Answer 4

• What is the shape of the capitulum?
• Is the scutum ornate?
• Are there festoons?

Question 5

How is sexual dimorphism obvious in ticks

Answer 5

• males: scutum over whole back
• females: anterior scutum

Question 6

How to ID ticks?

Answer 6

• Is the scutum coloured (ornate)? (if YES, is it white or yellow? - White splatter (Dermacentor spp); - yellow dot (Amblyoma sp. female).
• if NO, is the basis of the capitulum parallel-sided or angled? Parallel (Ixodes spp.); Angled (Rhipicephalus spp)
• Dermacentor, Amblyomma, & Rhipicephalus all have festoons

Question 7

Who is Dermacentor variabilis?

Answer 7

• American Dog tick
• 3 host tick
• potentially transmits: Rocky Mountain Spotted Fever (rickettsia), Tularemia (bacterium), Ehrlichia canis (& other spp; rickettsia)
• dominant tick in SK, MB, & east
• pathogen prevalence in ticks in western Canada is v low

Question 8

Who is Dermacentro andersoni?

Answer 8

• Rocky mountain wood tick
• transmits: Rocky Mountain Spotted Fever (rickettsia), Tularemia (bacterium), Colorado Tick Fever (virus)
• causes Tick paralysis in interior BC
• dominant tick in BC & AB
• pathogen prevalence in ticks in western Canada is v low

Question 9

What are the defining features of Dermacentor spp?

Answer 9

• ornate scutum w/ white markings, festoons, short capitulum

Question 10

what are spiracles & how can we use them to tell species apart?

Answer 10

• how the ticks breath
• small circular spots around the spiracle for Dermacentor viriabilis, large circular balls around the spiracle for Dermacentor andersoni

Question 11

What is the life cycle of Dermacentor variabilis and Dermacentor andersoni?

Answer 11

• adults lay eggs in the environment -> eggs hatch into larvae -> larvae (6 legs) go on host #2 (Rodents, rabbits, etc.) -> takes a blood meal & then drops off into the environment -> larvae become nymphs -> nymphs (8 legs) go one host #3 (rodents, rabbits, etc.) -> takes a blood meal & then drops off into the environment -> nymphs become adults -> adults (8 legs) go on to host #1 (Dogs, people, ungulates) -> take a blood meal & then drop off into
  environment IN SPRING
• environment = soil surface/ vegetation
• can take as little as 8 weeks, usually 2 years

Question 12

Who is Rhicephalus sanguineus?

Answer 12

• Brown dog tick
• 3 host tick (all hosts are dogs - rarely people)
• transmits: Rocky Mountain Spotted Fever (rickettsia), Ehrlichia canis (rickettsia), Babesia canis (piroplasmosis, protozoan; not in Canada), Hepatozoon canis (apicomplexan; not in Canada)
• introduced from warmer regions; seen in kennels & houses

Question 13

Defining features of Rhipicephalus sanguineus

Answer 13

• inornate scutum
• festooned
• Darth Vader helmet capitulum

Question 14

Rhipicephalus sanguineus life cycle?

Answer 14

• adults lay eggs in the environment -> eggs hatch into larvae -> larvae (6 legs) go on host (DOG, 4 days) -> takes a blood meal & then drops off into the environment -> larvae become nymphs -> nymphs (8 legs) go one host (DOG, 4 days) -> takes a blood meal & then drops off into the environment -> nymphs become adults -> adults (8 legs) go on to host (DOG, 8 days) -> take a blood meal & then drop off into environment
• environment = often indoors
• takes months to years

Question 15

Who are the Ixodids?

Answer 15

• Ixodes scapularis (I. dammini): eastern deer tick/ black legged tick
• Ixodes pacificus: western deer tick/ black legged tick
• 3 host ticks
• transmit: Anaplasma phagocytophilum, Borrelia burgdorferi (LYME DISEASE). Borrelia miyamotoi (RELAPSING FEVER), Babesia microti, Ehrlichia muris, Francisella tularensis, POWASSAN VIRUS

Question 16

Defining features of Ixodes pacificus?

Answer 16

• inornate scutum, no festoons, long parallel capitulum
• genital pore
• anal groove ANTERIOR to anus
• on dogs in BC in fall & winter

Question 17

Life cycle of Ixodes scapularis?

Answer 17

• generally takes 2-3 yrs
• adults lay eggs in the environment IN WINTER -> eggs hatch into larvae -> larvae (6 legs) go on host #2 (white foot mice, rodents, rabbits) -> takes a blood meal & then drops off into the environment -> larvae become nymphs -> nymphs (8 legs) go onto host #3 (rodents, songbirds, pets, people) IN SPRING -> takes a blood meal & then drops off into the environment -> nymphs become adults IN SUMMER -> adults (8 legs) go on to host #1 (white tailed deer, pets, people) IN FALL -> take a blood meal & then drop off into environment

Question 18

What is three-tiered tick prevention?

Answer 18

• Client education (modify behaviour & environment; tick checks & identification to genus level; remove w/in 12-24 hrs)
• tick prevention (repellents: topical insecticides, collars; systemic: oral isoxazolines, topical spot-ons)
• testing & vaccination for Lyme disease? (test only if clinical signs & plausible exposure; vaccinate only if living in or travelling to endemic regions (S. MB, ON, QC, NS, NB, eastern USA)

Question 19

What does lyme disease look like in Ca?

Answer 19

• few dogs exposed in non-endemic regions
• many dogs exposed in endemic regions
• exposure can be detected using serology (ex: 4DX snap) @ least 6-8 WEEKS AFTER TICK BITE
• 95% will never develop clinical signs
• @ 2-5 months post exposure, may see: shifting lameness (arthritis), anorexia, fever; nephritis is the most common clinical sign; rarely neurological, cardiac, & ocular issues