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PARASITOLOGY - 1 > 6a – Heartworms (Non-GI Nematodes) > Flashcards

6a – Heartworms (Non-GI Nematodes) Flashcards

1
Q

Dirofilaria immitis (heartworm): species

A
  • Dogs
  • Rarely cats (rarely patent)
  • Very rarely people (not patent)
    o Can get subcutaneous and lung nodules when infected
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2
Q

Dirofilaria immitis (heartworm): adults

A
  • R. ventricle and pulmonary arteries
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3
Q

Dirofilaria immitis (heartworm): L1 larvae (in blood film)

A
  • Tapered head
  • Very small
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4
Q

Dirofilaria immitis (heartworm) vs. Acanthocheilonema reconditum

A

5 R’s of Reconditum:
- Round head
- Rare
- Reduced size and number
- Recurved tail
- Rapid movement
- *history is important (if not in area with heart worm it will likely be A. reconditum)

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5
Q

Dirofilaria immitis (heartworm): lifecycle (IMPORTANT!!!!)

A
  • Adults in heart
  • Microfilariae (L1) into blood
  • Picked up as L1 by vector (mosquitoes)
  • L1->L3 in vector (2 weeks, if above 14 degrees at ALL times or will take longer)
  • L3 goes into salivary glands, when take second blood meal=infects host with L3
  • Directly to heart and develop
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6
Q

Dirofilaria immitis (heartworm): PPP

A
  • 6-7 months
  • *long period between being infected and being patent
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7
Q

Dirofilaria immitis (heartworm): adults and L1 lifespan

A
  • Adult: 5-7 years
  • L1: 2 years
  • *history is important)
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8
Q

Dirofilaria immitis (heartworm): pathogenesis

A
  • Often asymptomatic
  • Decreased exercise tolerance
  • Coughing
  • Anorexia
  • Weight lose
  • *parasite antigen/antibody complex can cause glomerulonephritis and proteinuria
  • Caval syndrome
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9
Q

Dirofilaria immitis (heartworm): severe cases

A
  • R. heart failure
  • Hepatic congestions
  • Ascites
  • Syncope
  • Death
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10
Q

Dirofilaria immitis (heartworm): caval syndrome

A
  • Small dogs, rare in cats
  • Worms block caudal vena cava/tricuspid valve
  • *requires immediate surgical removal of worms
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11
Q

Dirofilaria immitis (heartworm): diagnosis

A
  • HISTORY (location and travel)
  • Clinical signs
  • Radiographs/ultrasound
  • Diagnostic tests
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12
Q

Dirofilaria immitis (heartworm): radiographs

A
  • Enlarged pulmonary arteries and right heart
  • May see worms, check for caval syndrome
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13
Q

Dirofilaria immitis (heartworm): diagnostic tests

A
  • Microfilarial concentration test (Knotts)
    o Looking for L1 in blood
  • Immunodiagnosis (SNAP test)
    o Adult female antigen detection (DOGS)
    o Antibody detection (CATS)
  • **do BOTH annually
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14
Q

Dirofilaria immitis (heartworm): testing recommendations

A
  • Who? Pets living in or travel to endemic regions
  • What tests? Antigen, Knotts or Abs
  • Where? Annually in endemic regions
  • When? At least 6 months after last possible exposure
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15
Q

Dirofilaria immitis (heartworm): why test?

A
  • Prior to starting preventatives
  • If suspect non-compliance in endemic region
  • To monitor success of treatment
  • Many drug companies will NOT cover cost of adulticidal treatment if pets are NOT tested annually
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16
Q

Why would a dog who is positive on antigen test be negative on Knotts test for microfilaria?

A
  • False positive
  • Tested too early in the day=not in blood yet (sync when they are likely to go into a mosquito)
  • Only females=no microfilaria
  • Senescence: not producing larvae
  • *if on monthly preventatives=masking (can kill of microfilaria but not the antigens)
17
Q

Why would a dog who was negative on antigen test have microfilaria in the buffy coat of a PCV tube?

A
  • Old infection: adults are all dead but microfilaria are alive still
  • Could be a different microfilaria
  • Maybe killed adults but not the microfilarias
18
Q

Dirofilaria immitis (heartworm): interpreting tests, false positive on antigen test

A
  • especially in low prevalence regions like western Canada
  • if suspect false positive=try a different test, then re-test in 3 months if still not convinced
19
Q

Dirofilaria immitis (heartworm): interpreting tests, false negatives on antigen and microfilaria tests

A
  • recent infections (immature females, PPP)
  • single sex infections
20
Q

Dirofilaria immitis (heartworm): interpreting tests, false negatives on antigen test

A
  • blocked antigen: antigen/antibody complexes
21
Q

Dirofilaria immitis (heartworm): interpreting tests, false positive on microfilaria tests

A
  • senescent infections (L1 may disappear after 9 months)
  • dogs on monthly preventatives (MASKING)
  • DIURNAL patterns in microfilaria activity in blood
22
Q

Dirofilaria immitis (heartworm): monthly preventatives (kill L3 and L4)

A
  • Ivermectin
  • Milbemycin
  • Selamectin
  • Moxidectin
    *resistance is developing
23
Q

Dirofilaria immitis (heartworm): antibiotic to kill

A
  • Wolbachia: Doxycycline
24
Q

Dirofilaria immitis (heartworm): adulticides (kill adults)

A
  • Melarsomine (Immiticide)
    *NOT in CATS=toxic (NEED TO DO HEART SURGERY TO PULL THEM OUT)
25
Q

Dirofilaria immitis (heartworm): microfilaricides (kill L1)

A
  • Ivermectin
  • Moxidectin
26
Q

Dirofilaria immitis (heartworm): salvage procedure if adulticide therapy is NOT possible

A
  • Use doxycycline with ivermectin or moxidectin
27
Q

Dirofilaria immitis (heartworm): treatments, preventatives

A
  • Start one month following first possibility of exposure
  • Continue until one month after the last possibility of exposure
  • (May-Oct in Canada)
28
Q

Dirofilaria immitis (heartworm): If treating adults

A
  • Need to be on bed rest
  • *risk of pulmonary thromboembolism
    o Depends on activity level of dog, intensity and extent of disease
29
Q

Dirofilaria immitis (heartworm): ecology and epidemiology

A
  • Domestic and wild canids are normal DH
  • Mosquitoe vectors
  • Endo-symbiotic bacteria
  • Seasonal transmission
  • Patchy geographic distribution
  • Low test positivity in dogs in Canada
30
Q

Dirofilaria immitis (heartworm): mosquito vectors

A
  • Aedes spp.
  • Anopheles spp.
  • Culex spp.
31
Q

Angiostrongylus vasorum (‘French heartworm’):

A
  • Dogs, wild canids, mustelids
  • In Canada: Newfoundland and Nova Scotia
  • Transmitted by gastropod IH
32
Q

Angiostrongylus vasorum (‘French heartworm’): life cycle

A
  • Adults in heart, shed L1 larvae
  • L1 picked up by slug or snail -> translate to L3
  • Eaten by host or paratenic host (ex. amphibians)
  • Go to heart and develop
33
Q

Angiostrongylus vasorum (‘French heartworm’): diagnosis

A
  • Clinical signs similar to Dirofilaria immitis
  • Can be more sever: DIC (rarely in CNS)
  • L1 detected on Baermann
  • L1 in bronchoalveolar lavage (BAL)
  • ELISA
34
Q

Angiostrongylus vasorum (‘French heartworm’): treatment

A
  • Monthly prophylaxis ML (moxidectin or milbemycin): April-November=slug season
  • ML or fenbendazole for adults

PARASITOLOGY - 1 (14 decks)

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