Non-GI nematodes Flashcards
Where do non-GI dwelling nematodes live?
Heart, lungs, urinary tract
Heartworms
-Dirofilaria immitis
-effects dogs, rarely cats and humans (SQ and lung nodules)
Dirofilaria immitis characteristics
Adult: Head has hemisphere on cone/point, live in SQ tissue
Dirofilaria immitis lifecycle
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
Dirofilaria immitis pathogenesis
-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
Dirofilaria immitis Diagnosis
-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)
Heartworm testing
-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)
Why would a dog who is positive on antigen test be negative on Knotts test for microfilaria?
-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)
Why would a dog who was negative on antigen test have microfilaria in the buffy coat of a PCV tube?
-old infection- dead adults but microfilaria still there
-different type of microfilaria
False negatives on antigen and microfilaria tests
-recent infection (immature females, PPP)
-single sex infections
False negatives on antigen test
-blocked antigen: antigen/antibody complexes
False negatives on microfilaria tests
-senescent infections (L1 may disappear after 9mths)
-dongs on monthly preventatives= masking
-diurnal patterns in microfilarial activity in blood
Heartworm adulticides
Melarsomine (Immiticide) for dogs
**toxic for cats
Killing adults can lead to thromboembolism
Heart worm microfilaricides
Kill L1 stage
Includes ivermectin and moxidectin
Monthly preventatives for heartworm drugs
-Ivermectin
-milbemycin
Heartworm preventatives
-Start one month following the first possibility of exposure and continue until one month after the last possible exposure
**May-Oct in Canada
Heartworm epidemiology
-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
French Heartworm
Angiostrongylus vasorum
-in dogs, wild canids, mustelids
-Newfoundland and Nova Scotia
-transmitted by gastropod intermediate hosts
Angiostrongylus vasorum lifecycle
- Adults in heart
- First stage larvae in feces
- Larvae (L1 to L3) in snail/slug IH
- L3 in Paratenic host or direct digestion by canids
French heartworm diagnosis
-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
French heartworm treatment
-Monthly prophylaxis April-Nov
Aelurostrongylys abstrusus life cycle
- Adults in lungs
- First stage larvae in feces or BAL
- Larvae in snail/slug IH
- L3 in Paratenic host or direct digestion by felines
Aelurostrongylys abstrusus epidemiology
-cats in BC and Atlantic canada
-often asymptomatic, may cause coughing and death
-ML or fenbendazole drugs
Crenosoma vulpis
-DH:dogs, wild canids
-Adults in bronchi/bronchioles, shed larvae in feces, larvae stages in gastropods IH
Filaroides osleri
-resides in airways
-DH: wild canids, hunting dogs
-nodules in tracheal mucosa
Filaroides hirthi
-resides in lung parenchyma
-dogs in kennels; immunosuppressed
Life cycle of Filaroides osleria AND hirthi
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
Pathogenesis of Filaroids osleri
-asymptomatic
-cough/retching triggered by exercise and cold
-nodules may obstruct air, cause cyanosis, and collapse
Pathogenesis of Filaroides hirthi
-often asymptomatic
-clinical only when immunosuppressed
-occasionally fatal bronchopneumonia
Management of Filaroides
-clean environment
-break vertical transmission
-repeat treatments with ML or fenbendazole
Capillaria aerophila
-dogs and cats, wild canids
-adults in trachea and bronchi, eggs shed in feces
Capillaria boehmi
-dogs and wild canids
-adults live in nasal and sinus cavities
-shed eggs in feces
Capillaria plica
-dogs, cats, wild canids
-adults live in bladder
-shed eggs in urine
Dioctophyma renale- Giant Kidney Worm
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
Dioctophyma renale life cycle
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
