Nematodes Part 2 Flashcards
Thelazia californensis definitive host/location
dogs, cats, sheep, deer, humans; conjunctiva and tear ducts
Thelazia californensis intermediate host
Face fly
Thelazia californensis infective stage
L3 deposited by face fly when feeding around the eye
Thelazia californensis clinical signs
Conjunctivitis, photophobia, excessive tearing
Thelazia californensis diagnosis
Observe parasites in eyes, L1 may be present in tears
Thelazia californensis treatment
Manual removal of parasites, ivermectin, control flies
Scientific name of giant kidney worm
Dioctophyme renale
Dioctophyme renale definitive host/location
Mink is the main host, also dogs, wolves, foxes, rarely cats, humans, pigs, cattle; kidney
Dioctophyme renale intermediate host
annelid (lives on surface of crayfish)
Dioctophyme renale paratenic host
fish, frogs
Dioctophyme renale infective stage
L3 encysted in IH or paratenic host
Dioctophyme renale prepatent period
5 mo - 2 yr
Dioctophyme renale clinical signs
Usually right kidney only, blocked ureter, peritonitis, renal failure
Dioctophyme renale diagnosis
Urine, adults
Dioctophyme renale treatment
Remove kidney, remove adults
Pearsonema plica definitive host/location
dogs, wolves, foxes; urinary bladder, pelvis of kidney
Pearsonema feliscati definitive host/location
cats; urinary bladder, pelvis of kidney
Pearsonema spp. paratentic host
Earthworm
Pearsonema spp. infective stage
L1 in earthworm
Pearsonema spp. prepatent period
2 mo
Pearsonema spp. clinical signs
Cysitis, irritation of bladder mucosa, usually asymptomatic
Pearsonema spp. diagnosis
Urine
Pearsonema spp. treatment
Fenbendazole, ivermectin, may need to re-treat
Eucoleus aerophilus definitive host/location
dogs, cats, foxes; respiratory tract
Eucoleus boehmi definitive host/location
dogs, foxes; paranasal sinuses, nasal cavity
Eucoleus spp. infective stage
Direct lifecycle, L2 in eggs
Eucoleus spp. prepatent period
40 days
Eucoleus spp. clinical signs
Coughing
Eucoleus spp. diagnosis
Fecal exam
Eucoleus spp. treatment
Fenbendazole, ivermectin
Filaroides hirthi definitive host/location
dogs, coyotes; lung parenchyma
Filaroides osleri definitive host/location
dogs, coyotes; nodules at bifurcation of trachea
Filaroides spp. infective stage
Direct lifecycle, L1 in feces, saliva, or respiratory secretions
Filaroides hirthi prepatent period
5 weeks
Filaroides osleri prepatent period
6-7 months
Filaroides spp. diagnosis
Fecal floatation, Baermann, radiography, endoscopy
Filaroides spp. treatment
Fenbendazole, ivermectin, remove nodules
Aelurostrongylus abstrusus definitive host/location
cats; lung parenchyma
Aelurostrongylus abstrusus intermediate host
land snails, slugs
Aelurostrongylus abstrusus paratenic host
rodents, birds, amphibians, reptiles
Aelurostrongylus abstrusus infective stage
L3 in IH or paratenic host
Aelurostrongylus abstrusus prepatent period
4-6 weeks
Aelurostrongylus abstrusus clinical signs
Coughing, nodules on lung surface
Aelurostrongylus abstrusus diagnosis
Fecal exam (L1), radiography
Aelurostrongylus abstrusus treatment
Fenbendazole, moxidectin, ivermectin?
Angiostrongylus cantonensis definitive host/location
rats; heart, pulmonary arteries
Angiostrongylus cantonensis intermediate host
snails, slug
Angiostrongylus cantonensis incidental hosts
dogs, humans, horses, opossums, birds
Angiostrongylus cantonensis paratenic hosts
crabs, shrimp, frogs, fish
Angiostrongylus cantonensis infective stage
L3 in IH or paratenic host
Canine neural angiostrongylosis
Hx of eating IH, progressive neurological signs, eosinophilic pleocytosis in CNS
Treat with prednisone, prognosis good
Angiostrongylus cantonensis clinical signs
eosinophilic meningitis, headache, paralysis
Angiostrongylus cantonensis treatment
Supportive care
Scientific name guinea worm of dogs (serpent on a stick)
Dracunculus insignis
Dracunculus insignis definitive host/location
dogs, foxes, cats, racoons, mink; subcutaneous tissues
Dracunculus insignis intermediate host
copepod
Dracunculus insignis paratenic host
frog
Dracunculus insignis infective stage
L3 in IH or paratenic host
Dracunculus insignis clinical signs
painful skin ulcers
Dracunculus insignis diagnosis
observe female under skin, see L1 from skin blister in water
Dracunculus insignis treatment
Fenbendazole, ivermectin (best results if treated within 90 days of infection)
Dirofilaria immitis definitive host/location
dogs, cats, ferrets, sea lions; pulmonary arteries, right ventricle
What are microfilariae?
Prelarval stage of Dirofilaria immitis
Dirofilaria immitis vector/intermediate host
mosquitos
What must Dirofilaria immitis be differentiated from?
Acanthocheilonema reconditum
Acanthocheilonema reconditum characteristics
Few in blood, progressive motion, “button hook” tail, a little smaller than D. immitis
Dirofilaria immitis occult infection
“hidden” infection, possibly due to single sex infection or small numbers, microfilariae NOT detectable
Dirofilaria immitis microfilarial periodicity
- Noctural - microfilariae present during evening hours
2. Incomplete - microfilariae never disappear completely from blood in 24 hour period
Dirofilaria immitis infective stage
L3 from mosquito bite
Dirofilaria immitis prepatent period
6-7 months
How many species of mosquitos harbor L3?
How many can transmit heartworm?
How many are common vectors?
70 species
23 transmit heartworm
14 are common
Dirofilaria immitis clinical signs
Due to infection in right ventricle and pulmonary arteries (increased vascular resistence, decreased cardiace output)
Can cause villous endarteritis
Dirofilaria immitis mild infection
intermittent cough, exercise fatigue, mild radiographic signs
Dirofilaria immitis severe infection
Severe radiographic signs (enlarged R ventricle, pulmonary artery enlargement), PCV <20%, persistent cough, ascites
Vena cava syndrome
Worms obstruct blood flow, interfere with tricuspid valve function, heart murmur, severe lethargy and weakness
Dirofilaria immitis diagnosis
- Detect antigen
2. Detect circulating microfilariae
When do dogs become antigen positive?
Most - 7 months post infection
Earliest - 5 months post infection
Missed doses of prevention may delay detection to 9 months post infection
When do dogs become microfilariae positive?
Earliest - 6.5 months post infection
Dogs with missed doses of prevention, but still receiving it occassionally may never be microfilariae positive
How often should dog’s receive antigen testing?
Annually
Should we doubt test results?
No, there is a high sensitivity and specificity
Antigen test: +
Microfilariae test: -
- Microfilariae not yet in circulation (maturing infection)
- Use of preventative without removing adult worms
- Use of microfilaricide without removing adult worms
- Unisex infection (female)
- Dog is true immune-mediated occult
- Failure to use microfilariae concentration test
Antigen test: -
Microfilariae test: +
- Microfilariae of another species (Acanthocheilonema reconditum)
- Microfilariae acquired transplacentally
- Adult worms removed or died, but microfilariae persist
- Contamination of test materials from previous sample
Antigen test: variable
Microfilariae test: Neg. or Pos.
- Fluctuating antigen level due to number of female worms, ages of worms, quality of sample
What is Wolbachia?
Wolbachia pipientis (only known species), gram negative bacteria related to ehrlichia and anaplasma, endosymbiote of Dirofilaria immitis
How is Wolbachia harmful to host?
Contributes to pulmonary and renal inflammation
Melarsomide treatment (age of worms affected and dose protocol)
NO activity in worms <4mo
AHS recommends 3 dose treatment (one, wait 30 days, then two 24 hours apart)
How to remove microfilariae?
Moxidectin (Advantage multi)
Why wouldn’t we want to specifically treat microfilariae?
High microfilarial numbers
All preventatives have microfilaricidal properties to some degree
Special name for clinical heartworm disease in cats
Heartworm associated respiratory disease (HARD)
What is the pathogenesis of heartworm associated respiratory disease in cats?
Vascular and airway disease caused by early death of IMMATURE heartworms
Stage 1 heartworm infection in cats
Immature adults in pulmonary arteries, cats tolerate worms
Stage 2 heartworm infection in cats
Worms dying - pulmonary inflammation, thromboembolism
Heartworm infection diagnosis in cats
Diagnosis is very difficult, low microfilariae numbers, antibody and antigen tests not very good