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SP1 Parasitology > Lecture 19 4/22/24 > Flashcards

Lecture 19 4/22/24 Flashcards

1
Q

What are the important characteristics of ticks?

A

-obligate blood sucking arthropods
-second most important pathogen vector for humans; first for animals
-affect wildlife, livestock, pets, and humans
-world wide distribution

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2
Q

Which features are used to identify ticks?

A

-basis capitulum
-scutum
-presence/absence of festoons

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3
Q

How can male ticks be distinguished from female ticks?

A

-females have a partial scutum
-males have a full scutum

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4
Q

What are the characteristics of hard ticks?

A

-present scutum
-anterior mouth parts that are visible from above
-one nymphal stage
-feeding time of several days
-female takes one blood meal
-female has one egg laying event w/ large quantity

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5
Q

What are the characteristics of soft ticks?

A

-absent scutum
-ventral mouth parts not visible from above
-several nymphal stages
-feeding time of 30-60 minutes
-female takes several blood meals
-female has several egg laying events w/ smaller egg quantities

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6
Q

What are the characteristics of Otobius megnini?

A

-soft tick
-often feed at night
-only larvae and nymphs are parasitic
-common on cattle
-can cause ear canal damage
-vector of Borrelia recurrentis

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7
Q

What are the types of hard tick host cycles?

A

-one host ticks: all three stages feed on same host without detaching; some Rhipicephalus spp.
-two host ticks: not common
-three host ticks: all three stages have separate feeding events; most common

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8
Q

Why is it important that ticks spread disease via their salivary glands?

A

the salivary glands are in the body, not the mouthparts, so it is okay if the mouthparts are left behind during removal

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9
Q

How can Ixodes spp. be identified?

A

anterior anal groove on ventral side of all life stages

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10
Q

What are the characteristics of Rhipicephalus sanguineus?

A

-aka brown dog tick
-mainly feeds on dogs
-hexagonal basis capitulum/Darth Vader helmet

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11
Q

What are the characteristics of Amblyomma americanum?

A

-aka lone star tick
-female has white spot on sputum
-long mouth parts
-short basis capitulum

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12
Q

What are the characteristics of Dermacentor variabilis?

A

-aka American dog tick
-ornate scutum
-all three palp segments appear stubby

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13
Q

What are the characteristics of Amblyomma maculatum?

A

-aka gulf coast tick
-long mouth parts
-short basis capitulum
-ornate scutum

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14
Q

What are the characteristics of Rhipicephalus annulatus?

A

-one host life cycle
-often seen in cattle
-“eradicated” from US, but occasionally comes into Texas
-“cattle tick” or “cattle fever tick”
-small, stubby palps

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15
Q

What are the characteristics of Rhipicephalus microplus?

A

-one host life cycle
-wider host range
-“southern cattle tick”
-small, stubby palps

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16
Q

What are the characteristics of Haemaphysalis?

A

-three host tick
-larvae and nymphs feed on birds and rabbits
-adults feed on larger mammals
-points on palps

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17
Q

Which species of Haemaphysalis are of importance?

A

-H. leporispalustris: rabbit tick
-H. chordeilis: bird tick
-H. longicornis: invasive tick with many hosts

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18
Q

What are the characteristics of Haemaphysalis longicornis?

A

-aka long-horned tick
-Asian tick recently introduced to US; started on east coast
-prefers cattle, sheep, and horses, but will feed on many hosts
-populations explode due to ability of female to reproduce without male

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19
Q

How do tick-borne diseases differ between direct and indirect?

A

-direct: tick causes the disease itself
-indirect: tick transmits an infectious organism

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20
Q

Which ticks are able to cause tick bites reactions?

A

all ticks, but esp. those with long mouthparts

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21
Q

What is the pathogenesis of tick bites?

A

-inflammation and blood loss
-deep painful bites are predisposed to bact. infections and myiasis

22
Q

What are the possible results of tick bites?

A

-tick worry
-tick anemia
-tick pyemia
-secondary infections
-myiasis

23
Q

How are tick bites treated and prevented?

A

-remove ticks and clean wounds
-provide supportive care
-provide topical or systemic parasiticides

24
Q

Which species are associated with tick paralysis?

A

-D. andersoni
-D. variabilis
-A. americanum
-A. maculatum
-Ixodes holocyclus

25
Q

What is the pathogenesis of tick paralysis?

A

-toxin is present in saliva
-acute ascending flaccid paralysis

26
Q

How is tick paralysis diagnosed and treated?

A

-find and remove tick; observe response
-supportive care
-dip animal if possible
-antitoxin available to Ixodes holocyclus

27
Q

What is transstadial transmission?

A

-pathogen is maintained within tick as it molts to next stage
-passed between different tick stages when they feed on infected hosts

28
Q

What is transovarial transmission?

A

-pathogen maintained through vertical transmission within population
-transmitted to offspring via ova

29
Q

Which bacterial diseases are spread via ticks?

A

-Lyme disease
-tularemia
-ehrlichiosis/anaplasmosis
-Rocky Mountain spotted fever

30
Q

What are the characteristics of Lyme disease?

A

-caused by Borrelia burgdorferi
-vectors include Ixodes scapularis, pacificus, and ricinus
-maintained transstadially
-infection spread by nymphs and adults

31
Q

How do rodents and white-tailed deer differ as reservoirs for Lyme disease?

A

-rodents can actually pass the bacteria to the tick
-white-tailed deer provide blood meals for already infected ticks, but cannot pass the bacteria

32
Q

How do the clinical signs of Lyme disease differ between the subclinical, acute and chronic forms?

A

subclinical:
-no signs
-strong antibody titer
acute:
-erythema migrans
-flu-like symptoms
chronic:
-cardiac signs
-neurologic signs
-arthritic signs

33
Q

What are the characteristics of Lyme disease in dogs and horses?

A

-serological screening of healthy animals can lead to overdiagnosis and/or overtreatment
-seropositive animals should be evaluated for proteinuria and co-infection; treated only if necessary

34
Q

Which clinical signs are seen in Lyme disease cases in animals?

A

acute:
-no signs typically recognized
chronic:
-fever
-anorexia
-depression
-shifting
-leg lameness
-proteinuria
-muscle pain
-joint pain

35
Q

What are the characteristics of Rickettsiae?

A

-intracellular gram neg.
-nonspecific clinical signs; flu-like signs, anemia, thrombocytopenia
-transstadial transmission
-treated with tetracyclines

36
Q

What are the characteristics of Rocky Mountain spotted fever?

A

-caused by Rickettsia rickettsii
-invades endothelial cells of small vessels
-vectors include D. andersoni, D. variabilis, and R. sanguineus
-transstadial and transovarial transmission
-amplifiers include wild rodents, humans, and dogs

37
Q

What are the clinical signs of Rocky Mountain spotted fever in humans?

A

-fever
-headaches
-joint and muscle pain
-generalized rash
-death due to renal failure, shock, and/or encephalitis

38
Q

What are the clinical signs of Rocky Mountain spotted fever in dogs?

A

-fever
-anorexia
-lymphadenopathy
-polyarthritis
-coughing/dyspnea
-vomiting and diarrhea
-edema

39
Q

Why is it important to do serological testing for Rocky Mountain spotted fever instead of PCR?

A

-pathogen lives inside cells, not in samples that can be run on PCR
-must detect immune response

40
Q

What are the characteristics of tropical canine pancytopenia?

A

-caused by Ehrlichia canis
-invades monocytes/macrophages
-replicate in morulae
-infects dogs and wild canids
-vector is R. sanguineus
-predilection for german shepherds
-treated with doxycycline

41
Q

What are the acute clinical signs of Ehrlichia canis?

A

-fever
-anorexia
-lethargy
-depression
-dyspnea
-lymphadenopathy
-thrombocytopenia

42
Q

What are the chronic clinical signs of Ehrlichia canis?

A

-pancytopenia
-pyrexia
-ocular abnormalities
-scrotal and limb edema
-hemorrhage
-epistaxis
-weight loss
-shock
-death

43
Q

What are the characteristics of canine granulocytic ehrlichiosis?

A

-caused by Ehrlichia ewingii
-invades granulocytes
-vector is A. americanum

44
Q

What are the clinical signs of Ehrlichia ewingii in dogs?

A

-often asymptomatic
-mild fever
-anorexia
-lethargy
-midl pancytopenia
-polyarthritis (chronic)

45
Q

What are the characteristics of equine and canine granulocytic ehrlichiosis?

A

-caused by Anaplasma phagocytophilum
-invades granulocytes
-zoonotic
-vectored by Ixodes spp.

46
Q

What are the clinical signs of Anaplasma phagocytophilum in dogs and horses?

A

-usually mild, seasonal disease
-fever
-lethargy
-edema
-pancytopenia
-petechiae

47
Q

Which tick spreads Cytauxzoon felis?

A

Amblyomma americanum

48
Q

Which tick spreads Hepatozoon americanum?

A

A. maculatum; must eat tick to get disease

49
Q

What are the potential testing options for tick-borne diseases?

A

-serological testing
-blood smear for Cytauxzoon and Babesia
-PCR on blood, tissue, or ticks

50
Q

What are the key points of tick control?

A

-year-long prevention for pets
-keep cats indoors
-advise clients of potential for TBD
-tick ID
-removing low lying vegetation and leaf litter
-excluding wildlife
-deer pop. control

SP1 Parasitology (23 decks)

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