Toxocara canis, cati, Toxascaris leonina Flashcards
(39 cards)
What is the definitive host (FH) for Toxocara canis?
Dogs & other canids
Toxocara canis primarily infects canines.
What is the PH for Toxocara canis?
Rodents, man
Humans can serve as accidental hosts.
What are the modes of transmission for Toxocara canis?
- Oral
- Transplacental
- Lactogenic (trans-mammary)
- Carnivorous/paratenic
These routes allow the parasite to spread to hosts.
What is the size range for male and female Toxocara canis?
Males: 10-12 cm, Females: 12-18 cm
What morphological features are characteristic of Toxocara canis?
- 3 lips
- Males have 2 spicules
- Esophagus with ventricle
- Long and narrow cervical alae
Describe the eggs of Toxocara canis.
- Medium size
- Subspherical
- 3 thick shells
- Rough surface
- Unembryonated
- 1 blastomer
- Dark brown
What is the life cycle of Toxocara canis?
Can have direct or indirect life cycle.
Direct:
- Unembryonated eggs are shed in the feces of the FH.
- Eggs embryonate (1-4 w) in environment and develops into L3 (infective larva).
- Following ingestion by FH, the infective eggs hatch and the larvae penetrate the gut wall.
- In younger dogs, the larvae migrate through the lungs and trachea, where they are coughed up and swallowed into the GIT. Adult worms develop in the SI.
- In older dogs larvae more commonly become arrested in tissues. Arrested larvae are reactivated in female dogs during late gestation and may infect puppies by the transplacental (major) or trans-mammary (minor) routes.
Indirect:
- Toxocara spp. can also be transmitted indirectly through ingestion of paratenic hosts.
- Eggs ingested by PH hatch and larvae penetrate the gut wall and migrate into various tissues where they encyst.
- The life cycle is completed when FH consume larvae within PH tissue and the larva develop into adult worms in the small intestine.
- Humans are accidental hosts who become infected by ingesting infective eggs or undercooked meat of infected PH. After ingestion, the eggs hatch and the larvae penetrate the intestinal wall and are carried by the circulation to a variety of tissues (liver, lung, heart, brain, muscle, eyes).
- While the larvae do not undergo any further development in these sites, they can cause local reactions and mechanical damages that causes toxocariasis.
How does Toxocara canis complete its life cycle?
Eggs are shed in feces, embryonate in environment, develop into L3, and are ingested by FH or PH.
What happens to the larvae in younger dogs after ingestion?
They migrate through the lungs and trachea, are coughed up, and swallowed into the GIT.
What are the two routes through which Toxocara canis can infect puppies?
- Transplacental (major)
- Trans-mammary (minor)
What are the clinical signs associated with Toxocara canis infection?
Depend on migration:
- somatic migration causes reactions and disorders.
- CNS: hemorrhages, necrosis, granulomas, meningitits, encephalitis
What is larva migrans ocularis (LMO)?
Migration of larvae to the eye, leading to inflammation and impaired vision.
- reinal scarring, red eyes, blindness
What is larva migrans visceralis (LMV)?
Migration of larvae to liver and lung, causing fever, hepatomegaly, respiratory symptoms, wheezing, coughing, seizures, myocarditits
What is the treatment for Toxocara canis?
Fenbendazole, Febantel
What is the recommended control measure for puppies against Toxocara canis?
Dehelmintization every month until 6 months of age; then 4 times a year until 1-2 years.
What is the primary diagnostic method for Toxocara canis?
Fecal examination
What is the definitive host (FH) for Toxocara cati?
Cat & other felines
What is the PH for Toxocara cati?
Human, rodent, chicken, earthworm, cockroaches
What are the transmission routes for Toxocara cati?
- Ingestion
- Lactogenic infection
- Transmission of L3 in PH
What is the size range for male and female Toxocara cati?
Males: 3-7 cm, Females: up to 12 cm
What are the morphological features of Toxocara cati?
Broader cervical ale and more convex than T. canis
What is a significant difference in the life cycle of Toxocara cati compared to T. canis?
PH plays a more significant role due to the predatory nature of cats.
Life cycle - Same as in T. canis but different in some ways:
1. PH (mice) – play a more significant role, due to the more aggressive predatory nature of cat.
2. Prenatal infection does not occur.
3. A percentage of larvae undergo tracheal migration, even in older, mature cats.
4. Trans-mammary transmission is the major route of infection.
What are the clinical signs associated with Toxocara cati infection?
- Respiratory disorders
- GIT disturbances
- Dehydration
- Anaemia
- Bad coat
What is the treatment for Toxocara cati?
Fenbendazole, Flubendazole, Pyrantel
