Non-GI nematodes

Question 1

Where do non-GI dwelling nematodes live?

Answer 1

Heart, lungs, urinary tract

Question 2

Heartworms

Answer 2

-Dirofilaria immitis
-effects dogs, rarely cats and humans (SQ and lung nodules)

Question 3

Dirofilaria immitis characteristics

Answer 3

Adult: Head has hemisphere on cone/point, live in SQ tissue

Question 4

Dirofilaria immitis lifecycle

Answer 4

PPP:6-7mths; adults live 5-7yrs, L1 live 2 yrs in blood
1.Adults in heart (L3 migrates to heart)
2. Microfilariae move into blood

PP:at least 14 days, temp greater than 14 degrees
3. Mosquitoes (L1-L2-L3 larvae)- L3 move into salivary gland and can reinfect dog DH

Question 5

Dirofilaria immitis pathogenesis

Answer 5

-often asymptomatic
-decreased exercise tolerance, coughing, anorexia, weight loss
Severe: R. heart failure, hepatic congestion, ascites, syncope, death
-parasite antigen/antibody= glomerulonephritis and proteinuria
-Caval syndrome: worms block caudal vena cava/tricuspid- need surgical removal

Question 6

Dirofilaria immitis Diagnosis

Answer 6

-be aware of geographical location of pets
-clinical signs; radiographs and Ultrasounds
-Tests: microfilarial concentration test, immunodiagnosis (Adult female antigen detection in dogs; antibody detection in cats)

Question 7

Heartworm testing

Answer 7

-pets living in or traveling to endemic regions
-at least 6 mths after last possible exposure (because testing for antigen; need adult to be present, not just L3)

Question 8

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

Answer 8

-false positive
-time of day (do not test early in day)
-female only infection (no males for reproduction)
-senescence infections (adults not producing larvae)
-masking (using preventatives)

Question 9

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

Answer 9

-old infection- dead adults but microfilaria still there
-different type of microfilaria

Question 10

False negatives on antigen and microfilaria tests

Answer 10

-recent infection (immature females, PPP)
-single sex infections

Question 11

False negatives on antigen test

Answer 11

-blocked antigen: antigen/antibody complexes

Question 12

False negatives on microfilaria tests

Answer 12

-senescent infections (L1 may disappear after 9mths)
-dongs on monthly preventatives= masking
-diurnal patterns in microfilarial activity in blood

Question 13

Heartworm adulticides

Answer 13

Melarsomine (Immiticide) for dogs
**toxic for cats

Killing adults can lead to thromboembolism

Question 14

Heart worm microfilaricides

Answer 14

Kill L1 stage

Includes ivermectin and moxidectin

Question 15

Monthly preventatives for heartworm drugs

Answer 15

-Ivermectin
-milbemycin

Question 16

Heartworm preventatives

Answer 16

-Start one month following the first possibility of exposure and continue until one month after the last possible exposure
**May-Oct in Canada

Question 17

Heartworm epidemiology

Answer 17

-DH: domestic and wild canids
-Mosquito vectors: Aades, Anopheles, Culex spp
-Endo-symbiotic bacteria= Wolbachia

-seasonal transmission, patchy geographic distribution
-low positivity in dogs in Canada

Question 18

French Heartworm

Answer 18

Angiostrongylus vasorum

-in dogs, wild canids, mustelids
-Newfoundland and Nova Scotia
-transmitted by gastropod intermediate hosts

Question 19

Angiostrongylus vasorum lifecycle

Answer 19

1. Adults in heart
2. First stage larvae in feces
3. Larvae (L1 to L3) in snail/slug IH
4. L3 in Paratenic host or direct digestion by canids

Question 20

French heartworm diagnosis

Answer 20

-clinical signs similar to Dirofilaria immitis
-can be more severe: Disseminated intravascular coagulation
-L1 detected by Baermann or bronchoalveolar lavage
-Adult detected by ELISA for antigen of adult

Question 21

French heartworm treatment

Answer 21

-Monthly prophylaxis April-Nov

Question 22

Aelurostrongylys abstrusus life cycle

Answer 22

1. Adults in lungs
2. First stage larvae in feces or BAL
3. Larvae in snail/slug IH
4. L3 in Paratenic host or direct digestion by felines

Question 23

Aelurostrongylys abstrusus epidemiology

Answer 23

-cats in BC and Atlantic canada
-often asymptomatic, may cause coughing and death
-ML or fenbendazole drugs

Question 24

Crenosoma vulpis

Answer 24

-DH:dogs, wild canids
-Adults in bronchi/bronchioles, shed larvae in feces, larvae stages in gastropods IH

Question 25

Filaroides osleri

Answer 25

-resides in airways
-DH: wild canids, hunting dogs
-nodules in tracheal mucosa

Question 26

Filaroides hirthi

Answer 26

-resides in lung parenchyma
-dogs in kennels; immunosuppressed

Question 27

Life cycle of Filaroides osleria AND hirthi

Answer 27

1.Adults (ovoviviparous)
2. Larvae released in feces or BAL; or in saliva and vomit (which can mean its transmitted to puppies)
3.Direct, internal autoinfection

Question 28

Pathogenesis of Filaroids osleri

Answer 28

-asymptomatic
-cough/retching triggered by exercise and cold
-nodules may obstruct air, cause cyanosis, and collapse

Question 29

Pathogenesis of Filaroides hirthi

Answer 29

-often asymptomatic
-clinical only when immunosuppressed
-occasionally fatal bronchopneumonia

Question 30

Management of Filaroides

Answer 30

-clean environment
-break vertical transmission
-repeat treatments with ML or fenbendazole

Question 31

Capillaria aerophila

Answer 31

-dogs and cats, wild canids
-adults in trachea and bronchi, eggs shed in feces

Question 32

Capillaria boehmi

Answer 32

-dogs and wild canids
-adults live in nasal and sinus cavities
-shed eggs in feces

Question 33

Capillaria plica

Answer 33

-dogs, cats, wild canids
-adults live in bladder
-shed eggs in urine

Question 34

Dioctophyma renale- Giant Kidney Worm

Answer 34

DH: dogs, wild canids, mustelids
-Adults= 1m long
-live in renal pelvis, often Right kidney; sometimes free in peritoneum
-destroy kidney parenchyma but usually subclinical
-incidental finding in spay
-common in MB and northern Ontario

Question 35

Dioctophyma renale life cycle

Answer 35

1.Adults (PPP: 4-5months)
2. Eggs in urine
3. Oligochaete Intermediate host (L1, L2, L3)
4. Direct ingestion of larvae or goes through paratenic host first