Ascarids Flashcards
Ascarid classification
Phylum: Nematoda
Order: Ascaridia
Family: Ascarididae
Which ascarids affect poultry?
- Ascaridia galli
- Heterakis gallinarum
Which ascarid affects swine?
Ascaris suum
Which ascarid affects equids?
Parascaris equorum
Which ascarids affect cats and dogs?
- Toxascaris leonina
- Toxocara cati
- Toxocara canis
Which ascarid affects raccoons and dogs?
Baylisascaris procyonis
Ascaridia galli - hosts
DH: birds in Galliforme order, ducks, waterfowl
PH: earthworm
Ascaridia galli - clinical signs
- anorexia
- unthriftiness
- diarrhea
- dull plumage
- decreased egg production
Heterakis gallinarum - hosts
DH: birds in order Galliforme, ducks, geese, swan, waterfowl
PH: earthworm
Heterakis gallinarum - clinical signs
Usually asymptomatic
- thickening, inflammation, nodules in cecum
Signs due to Histomonas meleagridis
High pathology, most important in turkeys
- cyanosis (blackhead)
- histomoniasis
- death 1 week post onset of signs
Ascaridia galli - life cycle
PH ingests L3 in egg –> DH ingests PH –> L3 released –> L3 enter SI –> L3 transient mucosal migration –> L4 emerges in SI –> adults in lumen of SI –> eggs in feces –> L1, L2, L3 in egg
Heterakis gallinarum - life cycle
DH ingests L2 in egg –> PH ingests L2 in egg –> DH ingests PH –> L2 released –> L2 hatch in gizzard, duodenum –> L2 enter liver, ceca, transient mucosal migration –> L3, L4, adult in ceca –> eggs in feces –> L1, L2 in egg
Heterakis gallinarum pathogenesis
Pale circular lesions in liver
- typhlitis: mucosal thickening, cecal hemorrhage
- vector of Histomonas meleagridis, multiply in nematode intestinal cells, ovaries, end up in egg –> nematode egg ingested by young bird, eggs hatch in SI and release protozoa in ceca
- most pathogenic in turkeys*
Ascaridia galli and Heterakis gallinarum - diagnosis
Fecal float-eggs
Adults: largest nematodes in birds, may eliminate in feces, may see on necropsy
Ascaridia galli management
- sanitation
- break life cycle
- ensure feed and water are not contaminated
- treat range soil
- avoid raising different species or different ages of birds together or in close proximity
- older chickens possibly resistant
Heterakis gallinarum - treatment
Mebendazole: distributed to flock in food and water
- rear on hardware cloth, no access to earthworms
Ascaris suum - hosts
DH: swine
PH: dung beetle, earthworms
Ascaris suum - life cycle
Eggs in feces –> L1, L2, L3 in egg –> DH ingests PH (PH ingests L3 in egg) or DH ingests L3 in egg –> egg hatches, releases L3 in SI mucosa –> L3 hepatopulmonary migration (10-15 days) –> L4 in alveoli, bronchi, trachea –> L4 coughed up and swallowed –> L4, adult in SI
Ascaris suum - pathogenesis
Liver
- cell destruction, intestinal hepatitis, localized fibrotic areas, rxn to larvae (milk spots)
Lungs
- hemorrhage, bronchitis, edema, pneumonia in young pigs
SI
- catarrhal enteritis, adult worms interfere with nutrition, obstruction or perforation
Ascaris suum - clinical signs
- coughing
- rapid shallow breathing (thumps)
- unthriftiness
- colic
- weight loss or reduced weight gain
Ascaris suum diagnosis
- fecal float: eggs
- necropsy: adult stages
- clinical signs
Ascaris suum - treatment and control
- some approved drugs
- eggs are extremely resistant
- strict sanitation
- facility specific
Parascaris equorum clinical signs are due to different ______
Stages
- larvae: coughing, bilateral mucopurulent nasal discharge
- adults: unthriftiness, potbellied appearance, inappetence, decreased weight gain, colic, obstruction, diarrhea
Parascaris equorum - life cycle
Eggs in feces –> L1, L2, L3 in egg –> DH ingests L3 in egg –> egg hatches, releases L3 –> L3 enters SI mucosa –> L3 hepatopulmonary migration –> L4 in alveoli, bronchi, trachea –> L4 coughed up and swallowed –> L4, adults in SI
Parascaris equorum diagnosis
- fecal float: eggs
- necropsy: adults
- history: peak prevalence at 4 months of age, decreases 6 months, age dependent resistance, immune response (attacks liver and lung stages)
Parascaris equorum - treatment and control
- some approved anthelmintics: fenbendazole, pyrantel tartate and pamoate
- resistance control
- eggs extremely resistant
- strict sanitation
- facility specific
Toxascaris leonina - hosts
DH: canids, felids, wild canids
PH: rodents
Toxascaris leonina - life cycle
Eggs in feces –> L1, L2, L3 in egg –> DH ingests PH or DH ingests L3 in egg –> no somatic migration!! –> L3 enter SI mucosa –> L3, L4 SI mucosa –> L4 adults in SI lumen –> adults in SI
PH: PH ingests L3 in egg –> somatic migration –> disseminate to tissues –> L3 arrest
Toxascaris leonina - pathogenesis
Toxascariasis
- no somatic migration so no mammary or transplacental transmission
- rarely infections are reported in humnas
- mixed infections are more pathogenic
- Toxocara spp. more common than Toxascaris leonina
Toxascaris leonina - clinical signs
Mixed infections
- unthriftiness
- potbellied appearance
- diarrhea
Toxascaris leonina - diagnosis
- fecal float: eggs, smooth shell, more space
- adults: cervical alae on anterior end, feces, vomitus, necropsy
Toxocara cati life cycle
- DH ingests L3 in egg: migration of larvae
- DH ingests PH: no migration
- transmammary: infection only when queen is lactating
- L3 arrests, reactivates –> mammary glands –> nursing kitten –> ingests L3, enters SI crypts
Toxocara cati - pathogenesis
- mechanical damage to SI
- interference with nutrition
- obstruction of SI
Toxocara cati - clinical signs
Often asymptomatic (even in kittens)
- pot bellied appearance
- failure to thrive
Toxocara cati - diagnosis
Adults
- feces
- vomitus
- necropsy
Toxocara canis - life cycle
- DH (> 6 months old): ingests L3 in egg, L3 penetrate SI and hatch, L3 hepatopulmonary migration +/- ALD, L4 coughed up and swallowed, L4 and adults in SI
- PH ingests L3: somatic migration, L3 arrest, reactivated, DH ingest PH
- L3 ALD, reactivate: mammary glands, pup ingests L3, L4, adults in SI
- L3 ALD, reactivate: transplacental, fetal liver, neonatal lungs, L3 to stomach, L4, adults in SI
Toxocara canis - pathogenesis
Transplacental most important
- age dependent resistance
- puppies: verminous pneumonia, enteritis, ulcers in SI, occlusion of SI, death with transmammary/placental
- clinical signs: potbelly, diarrhea, vomiting, unthriftiness
Toxocara canis - diagnosis
- fecal float: eggs
- adults: cervical alae
Toxocara vs Toxascaris eggs
Toxascaris leonina: smooth surface, empty space within egg
Ascarids in dogs and cats - prevalence
- Toxocara common worldwide
- virturally all pups born with T. canis
- geographic distribution of Toxascaris leonina more focal than Toxocara
- infection with Toxascaris leonina less frequent
_________ and ________ contribute to high prevalence even in well cared for pets
Transplacental transmission of Toxocara canis and hardy larvated eggs
Baylisascaris procyonis
Ascarid of raccoons, occassionally found in dogs
- midwest, NE west coast, emerging in SE
- direct transmission: young raccoon ingests egg with L2, hepatopulmonary migration
- indirect transmission: PH (small mammals, birds), older raccoons ingest PH
Baylisascaris procyonis - life cycle
- raccoons ingest embryonated eggs or PH
- humnas accidental hosts (ingest eggs)
- VLM and OLM in humans
- dogs: alternate DH
Why is B. procyonis a concern?
Raccoon latrines
- children playing
- dogs act as DH (shed eggs)
- can spread near people
Toxocariasis
Parasitic disease caused by migrating larvae of 2 species of Toxocara roundworms
- T. canis from dogs, and T. cati from cats
What are 2 major forms of toxocariasis?
- visceral toxocariasis
- ocular toxocariasis
Larva migrans
Migration of helminth larvae through tissue in suboptimal hosts
VLM
- preschool children
- organs invaded: hypersensitivity rxn, damage to organ
Neural larva migrans
Some enter CNS and rest migrate to body
OLM
Older children and young adults
- opthalmologic lesions
- larvae die –> granuloma
- unilateral
- partial/permanent blindness
Baylisascaris pathology
DH: no significant lesions
- other hosts: mechanical damage to tissues, granulomas, lung damage, CNS lesions, inflammation, hemorrhage, necrosis
Baylisascaris prevalence
Occurs in raccoons across US and Canada
- midwestern, northeastern, western states
- isolated in Texas, Florida, Appalachia
- > 90% adult raccoons infected
