Nematodes Flashcards
Describe Toxocara canis (canine ascarid)
- Live in the SI
- adults are very large (up to 18 cm)
Describe the life cycle of T. Canis
- Adults found in the SI of the DH
- non-larvated eggs leave DH via feces
- eggs larvate in environment
- Larvated egg is infective to DH
- possible routes of transmission:
- Direct transmission (ingestion)
- prenatal/transuterine
- colostral/lactogenic
- ingestion of paratenic host
Direct transmission of T. Canis in dogs <3 months old
- Ingest infective larvated egg
-
tracheal migration
- Larva hatch from egg in duodenum —> penetrate intestine and migrates to mesenteric l.n. —> migrates to liver — heart — pulm art — lungs
- molts — alveoli —bronchioles —trachea — coughed up/swallowed —stomach
- molts to L4/L5 in SI - mature to adult
- PPP = 3-4 wks
Direct transmission of T. Canis in dogs > 3 months old
- Ingest infected larvated egg
-
Somatic migration
- larva hatches from egg in duodenum
- Penetrates intestine - migration, enters systemic circulation —> returns to heart (does NOT penetrate alveoli)
- larvae encyst (hypobiotic) in various tissues (liver, lungs, etc)
- No maturation occurs
Prenatal/transuterine transmission of T. Canis
-
Most common way puppies infected
- hypobiotic larvae - mobilize day 42 of pregnancy
- larvae migrate to fetuses
- Liver to fetus
- larvae in lungs at birth — alveoli — bronchioles — trachea —coughed up/swallowed —stomach
- L4/L5 in SI - mature to adults in approx. 2 weeks
- Eggs are found in puppy fecesin by 23-40 days old
Colostrum/lactogenic transmission of T. Canis
- Larvae in mammary tissues —> infected during lactation
- larvae passed to puppies via colostrum
- go directly to stomach — SI
- NO migration
Transmission of T. Canis via ingestion of a paratenic host
-
Ingest paratenic host with encysted larvae
- rodents, sheep, pigs, earthworms
- larvae go directly to stomach— SI
- NO migration
How do the life cycles of T. Cati and T. Leonina differ from that of T. Canis?
T. Cati
- direct transmission - tracheal migration
- ingest paratenic host - rodents, roaches, earthworms
- lactogenic transmission - if newly infected
- PPP = 8 weeks
T. Leonina
- direct transmission - no migration
- ingestion of paratenic hosts
Describe the disease caused by ascarids
- More problematic in young puppies/kittens
- heavy infections: death rare
- pnemonia (migrations)
- V/D, obstructions
- focal CNS lesions
Describe Toxocara cati
- Habitat: SI of cats
- Adults are smallest of ascarids
- Eggs: dark center, rough shell, smallest
Describe Toxocaris leonina
- Habitat: SI of cats and dogs
- Adults larger than T. Cati, smaller than T. Canis
- Eggs: hyaline center, smooth shell
Which ascarid is which?
How do you diagnose Ascarids?
- Eggs in fecal float, adults in feces
- Usually in puppies
How do you treat Ascarids?
- Dogs and cats: Fenbendazole, milbemycin, moxidectin, pyrantel
- Cats (T. Cati): selamectin, emodepside
- Treat nursing dams with litter - every 2 weeks until 12 weeks, then monthly until 6 mo
- Pregnant bitches: Fenbendazole, ivermectin
How do you control ascarids?
- Remove feces daily - clean, then bleach
- rodent control
Describe visceral larval migrants (VLM)
- T. Canis
-
Chronic granulomatous lesions due to larval migrations
- often liver, lungs, brain, eye
- enlarge liver
- loss of weight, appetite, persistent cough
-
Human is paratenic host
- children - dirt eaters
Describe Baylisascaris procyonis
- Ascarid nematodes
- large, milky white
- adults very large: 12-24 cm
- eggs: feces of DH
- ellipsoidal, dark brown
Describe the life cycle of B. Procyonis
- DH: raccoons, dogs, kinkajous
- Direct transmission: larvated eggs
- PPP: 50-76 days
- Ingestion of paratenic host
- mice, woodchuck, rabbit, bird, humans
- PPP: 32-38 days
- Eggs released by DH
- up to 2 weeks to larvate in environment
How is B. Procyonis transmitted to humans?
- Ingestion of larvated eggs
- contaminated food/water
- hay, straw, bedding
- geophagy or pica
- consumption of raw meat
What are the clinical signs of Baylisascaris infections in the DH?
- Usually none in raccoons or dogs
- heavy infections (raccoons) have been associated with intestinal obstruction
What are the clinical signs of Baylisascaris infections in the paratenic hosts?
- rodents, rabbits, primates, birds = high susceptibility
- severity varies with species and # of larvae
- Can be none - low # of larvae that fail to migrate to CNS
- Resp distress - high # of larvae migrate thru lungs
- Granulomas -large # of worms migrate thru tissues
- Invasion of spinal cord or brain - causes hemorrhage, necrosis, inflammation
- circling, torticollis, paresis, paralysis
What parasite is this?
Baylisascaris procyonis
How do you diagnose B. Procyonis in the DH?
Eggs in fecal float
How do you treat B. Procyonis?
- Adults (DH)
- pyrantel, piperazine, Fenbendazole, milbemycin, moxidectin
- Migrating larvae
- low level/early CNS infection possible - guarded prognosis
- albendazole + steroids
- Decontaminate area
- heat: boiling water, steam cleaner, flame gun, autoclave, burning straw
How do you manage B. Procyonis?
- Keep food/bedding away from raccoons that could defecate in product
- do not
Describe Thelazia californensis (eyeworm)
- Habitat: conjunctiva and tear ducts
- DH: dogs, cats, sheep, humans
- IH: face fly (Musca autumnalis, Fannia)
- Morph:
- Adults 8-18 mm
- Egg - embryonated, hatch in uterus of female worm
- Larvae - L1
Describe the life cycle of T. californensis
- First stage larvae (L1- in tears) ingested by face fly
- Molt to L3 in fly
- L3 larvae deposited when the fly feeds around the eye
- Mature to adults in the conjunctiva/lacrimal duct
Describe the disease process caused by T. californensis
- lesions result only from large # of worms
- conjunctivitis, keratitis
- photophobia
- excessive tearing
How do you diagnose T. californensis?
- observe parasites on eye surface, conjunctival sac
- lacrimal secretions may contain L1 larvae
How do you treat T. californensis?
- Remove parasites - manual, brush or irrigation
- Ivermectin
- Control Musca autumnalis
Describe Dioctophyme renale (giant kidney worm)
- Habitat: kidney
- DH: dogs, wolves, foxes, mink (main DH), rarely - cats, humans, pigs, cattle
- IH: annelid (Lumbriculus sp.) - lives on the surface of crayfish
- Possible paratenic hosts - fish, frogs
- Morph:
- Adults LARGE 14-100 cm long
- Eggs - barrel shaped, bipolar plugs, rough shell, nonembryonated
Describe the life cycle of of D. renale
- Eggs leave DH via urine – viable up to 5yrs in environment
- ingested by annelid (IH) - develop to L3
- paratenic host may ingest annelid/crayfish - L3 encyst
- DH ingests annelid/crayfish or paratenic host
- L3 excysts – leaves intestine, migrates to kidney - matures
- PPP = 5 mo - 2 yr
Describe the clinical signs and disease process caused by D. renale?
- usualy right kidney only: no clinical signs
- Adults: block ureter, peritonitis, renal failure
What is this parasite?
Dioctophyme renale
How do you diagnose and treat D. renale?
Dx: urine, adults
Tx: none, remove adults, kidney?
Describe Pearsonema plica (P. feliscati) - urinary bladder worm
*aka Capillaria plica/feliscati
- Habitat: urinary bladder, renal pelvis
- DH:
- Cats: P. feliscati
- Dogs, wolves, foxes: P. plica
- Paratenic host: earthworm
- Morph:
- Adults: 13-60 mm
Describe the life cycle of P. plica/feliscati
- Eggs leave DH via urine - larvate to L1
- Egg w/ L1 ingested by earthworm (IH) - L1 in tissues
- DH ingests earthworm - larvae released in intestine
- L1 excysts - penetrates intestine, matures in mucosa of urinary bladder
- PPP = 2 mo
What are the clinical signs of the disease caused by Pearsonema spp.?
- mostly asymptomatic
- irritation of bladder mucosa, cystitis
How do you diagnose and treat Pearsonema spp.?
Dx: urine
Tx: none approved, fenbendazole, ivermectin, may need to repeat
Describe Eucoleus aerophilus (E. boehmi) - lungworms
- Habitat:
- E. aerophilus - resp tract of dogs, cats, foxes
- E. boehmi - nasal cavity, paranasal sinuses of dogs, foxes
- Direct life cycles
- Morph:
- Adults: 1.5-4 cm
- Eggs:
- E. aerophilus - netted
- E. boehmi - pitted
Describe the life cycle of Eucoleus spp.
- Adults in lungs, eggs leave DH via feces
- Eggs larvate
- DH ingests larvated egg - larvae released in intestine, penetrate mucosa
- Larvae migrate to lungs – mature in bronchioles, bronchi, and trachea
- PPP: 40d
What is this parasite?
Eucoleus aerophilus
Describe the clinical signs and the disease process caused by Eucoleus spp.
- usually asymptomatic
- severe infections: coughing, nasal d/c, bronchitis, pneumonia, anorexia, dyspnea
- 2ndary bacterial infections possible
- mucosal edema, inflammation, hemorrhage
How do you diagnose and treat Eucoleus spp.?
Dx: fecal exam, differentiate from similar eggs
Tx: experimental
- E. aerophilus (cats) - imidacloprid, moxidectin
- E. boehmi (dogs) - milbemycin, imidacloprid, moxidectin
- Ivermectin or fenbendazole
Describe Spirocerca lupi (esophageal worm)
- Habitat: caudal esophagus
- DH: dogs, foxes, wild and domestic felids
- IH: dung beetle
- Possible paratenic hosts: amphibians, reptiles, birds
- Distribution: worldwide, mainly tropical/subtropical regions
- Morph:
- Adults: coiled, bright red (30-88 mm)
- Eggs: larvated, thick shell
Describe the life cycle of S. lupi
- Larvated eggs found in the lumen of esophagus, make their way to intestine – out via feces
- Eggs ingested by dung beetle (IH) - develops to L3
- Paratenic host may or may not be utilized - L3 encysts
- IH or paratenic host ingested by DH - L3 migrates from stomach - gastric arteries - aorta
- Remain in aorta for >2mo - migrate to esophagus – nodule formation/mature/mate
- PPP = 5-6 mo
Describe the clinical signs of the disease process caused by S. lupi
-
Larval migration: hemorrhage, inflammatory reactions, necrosis
- roughened aorta, aneurysms, death
- Adults: nodule formation (1-4 cm) - obstruction of esophagus, vomiting, emaciation +/- mild anemia
What parasite causes this lesion?
Spirocerca lupi
What parasite caused this lesion?
Spirocerca lupi
How do you diagnose S. lupi?
- Flotation - high specific gravity
- Endoscopy (most sensitive)
- Radiography - esophageal mass, undulant border of aortic wall, spondylitis
How do you treat S. lupi?
- ivermectin +/- oral prednisolone
- doramectin
How do you control S. lupi?
- prevent hunting or scavenging (ingesting paratenic host)
- prompt removal of feces
- controlling coprophagous beetles usually not feasible
Describe Physaloptera praeputialis (P. rara) - the stomach worm
- DH:
- P. praeputialis - cats
- P. rara - dogs
- IH: coprophagous beetles, roaches, grasshoppers
- Possible paratenic host: snake, rat, frog
- Morph:
- Adults 14-48 mm
- Eggs: small, oval, smooth, thick shell, larvated
Describe the life cycle of Physaloptera spp.
- Larvated eggs pass out of DH - via feces
- Eggs ingested by beetle, cockroach, grasshopper (IH) - develops to L3
- Paratenic host may or may not be utilized - snake, rat, frog; L3 encyst
- IH or paratenic host ingested by DH - L3 released into stomach - attach to mucosa, mature
- PPP = 5-6 mo
Describe the clinical signs and disease caused by Physaloptera spp.
- usually asymptomatic
- Adults: edematous wounds in stomach - continue to bleed, chronic vomiting, eroded/inflamed mucosa
How do you diagnose Physaloptera spp.?
- fecal or vomitus exam - high specific gravity
- dark, tarry feces
- adults in vomitus
- endoscopy