Ascaridoidea - dog/cat Flashcards
Name some important Toxicara spp. in small animals. What kind of parasite are these?
- T. canis (dog, fox)
- T. cati (cat)
- T. leonina (dog, cat)
- They are nematodes (endoparasites, helminths, nematodes/roundworms)
What kind of life cycle does T. canis have?
What are its routes of infection?
- Direct LC
- Routes of infection:
- Host to host (fecal-oral route)
- transmammary
- transplacental
- paratenic host (IMH but not necessary for development)
What determines the outcome of infection in a dog/cat with Toxicara infection (i.e. development of adult worms or ALD)?
Depends on the age of the animal infected.
- if less than 3 months - infection more likely to produce adult worms
- if older than 3-6 months - infection more likely to cause larval arrest in tissue
In Toxicara canis infection, what is the infective stage of the life cycle? Is this in the egg/free living larva/or in IMH?
Is the LC direct or indirect? If indirect, what is the IMH?
Does this spp migrate in the final host?
- L3 is infective. It is in the egg (develops from L1-L3 in the egg, in the environment).
- Direct LC. No IMH, but can be transmitted by paratenic host (bird, rodent) - no migration following infection of dog from paratenic host.
- There is migration in the final host if acquired from the environment. Hepatotracheal migration. If acquired via transplacental route, there technically is migration from lungs to SI when pup is born. If acquired from paratenic host, there is NO migration. If acquired via transmammary route there is NO migration.
What is the PPP in Toxicara canis? (normal direct, fecal-oral infection)
4-5 weeks
Describe the life cycle of Toxicara canis during transplacental infection.
What is the PPP in this type of infection?
- L3 egg ingested by bitch from environment
- L3 hatches in SI and migrates to tissue (ALD)
- L3 activates ~3 weeks pre-partum
- L3 migrates from bitch to pup lung
- at birth, L3 migrates from lung to SI via bronchi, trachea, esophagus
- L3-L4-adult in SI of pup
- PPP is 16 -21 days (hard to measure)
***bold is in bitch
***underlined is the transfer from bitch to pup
What are some important features of Toxicara canis epidemiology?
- ~100% of pups infected via transplacental route
- Transmammary transmission can be possible for up to 5 weeks
- Highest level of infection is in pups under 6 months of age
- intestinal infection in pup is temporary
- arrested L3’s resistant
What are some important features of Toxicara canis eggs?
- unembryonated egg is not infective - takes about 4 weeks to reach infectivity
- eggs are sticky and very resistant to environmental conditions
- thick pitted surface
Why is Toxicara canis so persistent in the dog population?
- Different routes of transmission
- ALD - gives rise to trans-mammary and trans-placental routes
- paratenic hosts can spread infection
- eggs very resistant in the environment
Toxicara canis can cause what condition in man?
- ocular larva migrans - L3 encysts in eye; affectted individual can be of any age
What are some general characteristics of Toxicara cati?
- No transplacental infection route
- Direct or transmammary route
- PPP ~8 weeks
- eggs very similar to T. canis
- Arrowhead appearance to adults
What are some general characteristics of Toxicara leonina?
How can you distinguish a T. leonina egg from a T. canis egg?
- Infects cats and dogs
- No migratory phase
- Ingestion of egg containing L3 (fecal-oral route) or by eating paratenic host (mice)
- no migratory phase
- PPP ~11 weeks
- Can be distinguished by its smooth egg shell
