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Parasitology 2018 > Lecture 3: Nematodes (heartworms) > Flashcards

Lecture 3: Nematodes (heartworms) Flashcards

1
Q

canine heartworm

A

dirofilaria immitis

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2
Q

adult dirofilaria immitis are found where

A

right ventricle, pulmonary arteries

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3
Q

filaria do not produce eggs but

A

free living larval stages called microfilaria

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4
Q

vector/IH of dirofilaria immitis

A

mosquitoes

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5
Q

must differentiate heartworm MFF from

A

acanthocheilonema reconditum (filaria trans by fleas but not considered a pathogen)

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6
Q

number of MFF in blood of acanthocheilonema vs dirofilaria

A

few - acantho

many - dirofilaria

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7
Q

motion of dirofilaria vs acanthocheilonema MFF

A

Dirofilaria are stationary, wiggle and stay in view

acanthocheilonema is progressive and will move out of view

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8
Q

shape of dirofilaria vs acanthocheilonema

A

acantho is curved, thinner, shorter, has curved thin tail

dirofilaria is straight with a tapered head, longer

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9
Q

occult infections

A

dog harbors male and/or female adults

single sex
low numbers

“hidden” infection = MFF NOT detectable in blood

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10
Q

best way to dx occult HW infection

A

Ag test

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11
Q

when are dirofilaria MFF most active in circulation

A

nocturnal and incomplete periodicity (never disappear from peripheral blood)

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12
Q

how many mosquito spp are common vectors for HW

A

14

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13
Q

__ are released by the female worm, mosquito feeds on dog and picks this stage up

A

MFF

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14
Q

MFF develop to infective __ in the mosquito in about 8 days (temp dependent)

A

L3 larvae

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15
Q

L3 larvae are deposited at the skin surface when mosquito takes blood meal; L3 enter DH via

A

mosquito’s bite wound

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16
Q

larvae migrate and molt and eventually mature in the

A

heart or lungs

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17
Q

prepatent period for dirofilaria immitis

A

6-7mo

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18
Q

what stage do the preventatives we give monthly affect

A

L3 the first 3d in circulation while molting to L4

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19
Q

worms are not detectable consistently using most test procedures until they are __ old

A

6-6.5mo

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20
Q

Ag positive test but do not see MFF

A

gravid female is detected by Ag test before birthing MFF

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21
Q

how many spp of mosquitos are known to transmit HW

A

24

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22
Q

Disease in dogs is mainly due to the

A

adult worms in the PA

23
Q

rough internal surface of PA is termed

A

villous endarteritis

24
Q

changes in circulation caused by HW

A 
Vascular resistance (right ventricle hypertrophy) 
decreased CO (exercise intoleracne, liver and kidney dz)
25
overrun with worms, infect atrium and vena cava
vena cava syndrome
26
diagnose HW
Detection of Ag and detection of circulating microfilariae
27
when are most dogs Ag positive that are not on routine preventatives
~7mo PI, can be as early as 5mo
28
when would dogs who missed a dose of preventative become Ag positive
~9mo PI pets on macrocyclic lactones may never develop MFF or they are transient in small numbers
29
what sample do you need for SNAP, witness, Heska POC Ag test
serum, plasma, or whole blood
30
what is the gold standard HW Ag test
diroCHEK HW Ag test (serum or plasma)
31
if get a positive on a POC test what should you do next
check for MFF and check a different POC test
32
what test measures MFF present
modified knotts
33
who should be tested for HW Ag and when
every dog annually pets not on preventative dogs over 7mo , retest 7-12 mo after starting prevents dog misses dose, retest 7-12 mo after restart AHS guidelines suggest testing at 6 and 12 mo
34
if switch HW preventatives when should you retest for Ag
4.5 and 9 mo after switch
35
should you trust HW Ag test results
yes, high sensitivity and specificity
36
What can cause a positive Ag test but negative MFF test
- young infection, no circ MFF yet - using preventatives w/o removing adults - female only infection - immune mediated occult - failure to use MFF concentration test
37
what can cause a negative Ag test but positive MFF test
- different spp of MFF - MFF aquired transplacentally - adults removed or died but still have circulating MFF - contaminated test
38
if antigen test is variable and MFF is negative or positive
fluctuating Ag levels (# worms, age worms, quality sample)
39
what is the susceptibility gap
the early stages are suseptible to macrocyclic lactones the later stages are susceptible to melarsomine inbetween no treatment will touch "teenage stage" = susceptibility gap
40
symbiotic gram negative bacteria related to Ehrlichia that is present in ALL life stages of dirofilaria immitis
Wolbachia pipientis
41
what do we know about Wolbachia and Dirofilaria
it contributes to pulmonary and renal inflammation, is important for biology and reproductive functions, necessary for worm survival
42
killing adult worms
melarsomine dihydrochloride (immiticide) NO activity against worms <4mo AHS recommends 3 dose protocol
43
what can help control clinical signs of PTE during HW tx
Steriods
44
What can help treat wolbachia and weaken HW before immiticide tx
doxycycline
45
What is a potent preventative that treats MFF but a modified knotts should always be done first to quantify MFF present
moxidectin (advantage multi)
46
cats infected with HW get what condition
heartworm associated respiratory dz (HARD); vascular and airway dz from death of IMMATURE HW in cats
47
stage 1 of HARD in cats
immature adults in PA, immune rxn suppressed and cats tolerate the worms
48
Stage 2 of HARD in cats
worms dying = inflammation and PTE worms rarely mature in cats
49
cats IS is killing the worms causing inflammation and death usually occurs from __ not the worms
PTE
50
dz in canines vs felines depends on
dogs: number of worms and size of dog cat: few worms cause dz
51
worms are __ lived in dogs/cats
long (dogs) | short (cats)
52
MFF in cats
usually amicrofilaremic
53
what organs are affected in dogs v cats
dogs: hear and lungs cats: lungs
54
treatment of HW in dogs vs cats
dogs: treatment available cats: only symptomatic tx, cannot use melarsomine in cats

Parasitology 2018 (8 decks)

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